The Things We Do for No Reason (TWDFNR) series reviews practices which have become common parts of hospital care but which may provide little value to our patients. Practices reviewed in the TWDFNR series do not represent black and white conclusions or clinical practice standards, but are meant as a starting place for research and active discussions among hospitalists and patients. We invite you to be part of that discussion. https://www.choosingwisely.org/

CASE PRESENTATION

A 54‐year‐old woman presented to the emergency department (ED) with shortness of breath. She reported that her primary care physician diagnosed her with chronic obstructive pulmonary disease (COPD). Her physician had prescribed her an albuterol inhaler to use as needed for shortness of breath. Over the past few weeks she had been trying to use the inhaler, but she noted that it did not seem to help her increasing wheezing, coughing, and sputum production. In the ED, she received continuous albuterol treatments via nebulizer, Solu‐Medrol 125 mg intravenously, antibiotics, and a chest x‐ray. She was admitted to the hospital medicine service for COPD exacerbation and started on nebulized bronchodilator treatments every 4 hours. By the fourth day of her hospital stay, she was discharged to home with an albuterol inhaler, oral prednisone, oral doxycycline, and a follow‐up appointment. Dedicated patient education regarding proper inhaler administration did not occur during hospitalization.

WHY YOU MIGHT THINK NEBULIZED TREATMENTS IN INPATIENTS ARE HELPFUL

Inhaled bronchodilators are a mainstay of therapy for acute obstructive pulmonary diseases, including COPD and asthma exacerbations.[1, 2] Inhaled bronchodilators may be delivered by metered‐dose inhalers (MDIs) or via wet nebulizers powered by compressed air or oxygen. Current practice patterns in EDs and hospital wards tend to favor the use of nebulizers due to many apparent advantages of these devices.[3] For instance, nebulizers do not require any special inhalation technique and can be effectively used by patients at any age.[3, 4] There is also a common perception that nebulizers are more effective, possibly stemming from the assumption that hospitalized patients have already failed their outpatient MDI therapy and an almost mystical belief in the healing power of mist. Moreover, many clinicians have been trained to routinely use nebulizer therapies and may lack sufficient knowledge or comfort about the relative efficacy and equivalence dosing of MDI therapies.

WHY NEBULIZERS ARE NOT BETTER THAN MDIs FOR PATIENTS HOSPITALIZED WITH OBSTRUCTIVE PULMONARY SYMPTOMS

Decades of research support that MDIs are effective, efficient, and less costly (depending on circumstances) than nebulizers for the routine treatment of obstructive pulmonary exacerbations.[3, 4, 5, 6, 7, 8, 9, 10, 11] The clinical effectiveness of MDIs has been shown in studies across populations of adults with acute COPD symptoms,[3, 4, 7, 8] as well as children and adults with asthma exacerbations.[3, 4, 5, 6, 9, 10] A 2005 joint report by the American College of Chest Physicians (ACCP) and the American College of Asthma, Allergy and Immunology (ACAAI), concluded none of the pooled meta‐analyses showed a significant difference between devices in any efficacy outcome in any patient group for each of the clinical settings.[4] Many different outcomes have been investigated, including forced expiratory volumes (FEV), peak flows, symptoms and specific symptom scores, and physical findings.[4]

Compared to MDIs, there are a number of drawbacks to the use of nebulizers: nebulizers are more expensive to buy and maintain, are less portable, and take longer to set up, use, and clean following each use.[12] In addition, nebulizers have been associated with greater increases in heart rate and tremors compared to MDIs, suggesting nebulizers lead to higher systemically absorbed ‐agonist doses.[4]

Of note, nearly all of the clinical effectiveness studies administered MDIs with a valved holding chamber or spacer, facilitating the delivery of drug to the airways.[3, 4] Although valved holding chambers are commonly referred to as a spacer, a true spacer does not have a valve and is rarely used today.[12]

THE EVIDENCE EXAMINING NEBULIZERS VERSUS MDIs IN PATIENTS WITH ASTHMA OR COPD EXACERBATIONS

A 2013 Cochrane review sought to establish the relative efficacy of MDIs with holding chambers versus nebulizers for children and adults who presented to a community setting or emergency department with acute asthma.[6] The review included a total of 1897 children and 729 adults in 39 randomized controlled trials. The authors judged the overall evidence to be of moderate quality. Children with acute asthma treated with MDIs in the ED had shorter lengths of stay in the ED (70 minutes vs 103 minutes), similar peak flow and FEV measurements, lower heart rates, and less tremor compared to children treated with nebulizers.[5, 6] There were no significant differences found between devices for the treatment of adult patients with asthma.[6]

In a separate double‐blind, randomized, placebo‐controlled study evaluating albuterol administered by nebulizer versus MDI with spacer for children <2 years old presenting to an ED with wheezing, the use of MDIs with a spacer and facemask was equally efficacious and may have led to fewer hospital admissions.[10]

Mandelberg et al. performed a double‐blind, randomized, placebo‐controlled trial for unselected adult patients presenting to an ED with obstructive pulmonary symptoms.[8] Patients received either 2 puffs of a placebo MDI with a spacer along with nebulized salbutamol 0.5 mL in 1.5 mL saline solution (n=25), or a salbutamol MDI along with a nebulized placebo saline solution (n=25). Treatments were repeated every 15 minutes up to 3 times, unless side effects occurred. Spirometric measurements were performed following each treatment. No differences were seen between the groups at any point during the study period. The authors concluded, Even in the setting of the unselected group of patient referrals to the [Department of Emergency Medicine] for episodes of severe airflow limitation, the clinical and objective bronchodilator responses to the administration of salbutamol are independent of the method of delivery: MDI with large spacer or aerosol nebulization.[8]

There are surprisingly few studies examining the use of nebulizers versus MDIs in the inpatient setting for both children and adults. Dolovich et al. reviewed 6 studies that included 253 total patients and reported no significant differences in pulmonary function between devices.[4] Based on these findings, the ACCP/ACAAI group recommended both nebulizers and MDIs with spacers/holding chambers are appropriate for use in the inpatient setting. Quality of evidence: good.[4]

WHY USE MDIs FOR INPATIENTS

If MDI and nebulizer treatments are equally effective, why change current practice? The use of MDIs, rather than nebulizers, in hospitals could lead to fewer side effects such as tachycardia, arrhythmias, and tremors. MDIs are also more portable and do not require specialized set‐up. Furthermore, MDI administrations during hospitalization may provide a golden opportunity to have respiratory therapists, pharmacists, or other health professionals spend time teaching patients proper inhaler usage, rather than providing time‐consuming nebulizer treatments.[13] In a recent study, approximately 86% of hospitalized patients with asthma or COPD could not demonstrate appropriate use of an MDI. However, 100% of patients were able to achieve mastery following a short teach‐back session.[14] It is conceivable that transitioning patients to MDIs earlier during hospitalization and providing them with education regarding proper MDI administration could instill confidence in their use of inhalers and result in downstream effects such as shorter lengths of stay, less frequent hospital readmissions, or improved quality of life.

MDI use may result in cost savings in certain settings, although the relative costs of nebulizer versus MDI treatments depends on many institution‐specific factors. Such factors include the institutional policies on who delivers the nebulizer or the MDI and how they are compensated and staffed. For example in the Nebs No More After 24 program initiated at the University of California, San Francisco, the vast majority of the realized cost savings are due to the reduction in respiratory therapist time spent delivering MDIs, which reflects the local policies and compensation structure.[13] Previous inpatient interventions to convert from nebulizers to MDIs also showed cost savings resulting from decreased labor needs.[15] In some hospitals, nurses deliver nebulizer treatments, whereas in others only respiratory therapists are allowed to provide nebulizers. Moreover, whether the MDI can go home with the patient upon discharge depends on whether the hospital has a dispensing pharmacy or not. Formal economic evaluations specific to the local institution are necessary.

WHAT WE SHOULD DO INSTEAD: ENCOURAGE THE USE OF MDIs FOR INPATIENTS

For effective inpatient MDI treatments, MDI technique must be good. Thus, it is vital to enlist the right people to provide proper MDI teaching and supervision. Respiratory therapists are generally trained for this task, and may be complemented by appropriately trained physicians, nurses, or pharmacists. Many institutions have successfully implemented respiratory therapist‐driven protocols for the administration of MDIs, which has led to measurable improvements in the utilization of appropriate respiratory care resources.[15, 16] At University of California, San Francisco, this was accomplished by recruiting respiratory therapists and nurses to help support the transition of patients from nebulizers to MDIs and to provide bedside teaching on proper MDI usage. The institution then launched a Nebs No More After 24 campaign that sought to transition patients from nebulizers to MDIs within 24 hours of hospitalization. This campaign included an educational program for physicians, prepared facilitator guides to assist attending physicians with teaching about the new initiative, publicity efforts including pens and strategically placed posters, and regular feedback regarding nebulizer utilization on the pilot ward. Although the evidence suggests that patients can be started on MDIs immediately upon presentation to the ED, the UCSF campaign focused on transitioning patients within 24 hours so to alleviate concerns about transitions in care between the ED and the medical ward, as well as between overnight and day teams. MDIs are only as or more effective than nebulizers if the correct administration technique is employed. The 24‐hour transition period allows for MDI teaching and transition during regular daytime hours.

Inpatient use of nebulizers may be more appropriate than MDIs for patients with dementia or altered mental status, as well as those in extreme distress resulting in an inability to coordinate inhaler usage. Very low health literacy may be an additional barrier to appropriate MDI teaching and usage.

RECOMMENDATIONS

In patients with obstructive pulmonary symptoms, transition patients from nebulizers to MDIs early in their hospital course, unless the patient is unable to use an inhaler due to altered mental status, dementia, or other circumstances. Ensure that patients are instructed and supervised on proper MDI technique. Enlisting respiratory therapists and appropriately trained staff (pharmacists, nurses, physicians) is key to the successful use of MDIs. Frequency and dosage of MDIs used should be comparable to that of nebulized treatments. Although studies have used a relatively wide range of albuterol MDI dosing, prior programs have determined a dose of albuterol 4 puffs via MDI as being equivalent to the standard albuterol 2.5 mg nebulizer dosage.[17, 18] Some studies have advocated for using a range of 2 to 10 puffs albuterol MDI, with the actual dose based on clinical response.[17] One study in children with mild acute asthma found that 2 puffs of albuterol by MDI was just as effective as higher doses delivered by MDI (610 puffs) or by nebulizer.[19]

CONCLUSION

MDIs with holding chambers are clinically equivalent to nebulizer therapy for the treatment of both children and adults with obstructive pulmonary symptoms, as long as MDI technique and MDI dosing is adequate. This is based on good data in the ED setting but fewer studies in adult inpatients. There are a number of advantages to the use of inpatient MDIs over nebulizers; MDIs are more portable, often less expensive to use, may result in fewer side effects, and will hopefully improve outpatient MDI technique. The delivery of MDIs during hospitalization should be accompanied with patient education regarding proper administration technique.

Do you think this is a low‐value practice? Is this truly a Thing We Do for No Reason? Share what you do in your practice and join in the conversation online by retweeting it on Twitter (#TWDFNR) and Liking It on Facebook. We invite you to propose ideas for other Things We Do for No Reason topics by emailing [email protected]

The Things We Do for No Reason (TWDFNR) series reviews practices which have become common parts of hospital care but which may provide little value to our patients. Practices reviewed in the TWDFNR series do not represent black and white conclusions or clinical practice standards, but are meant as a starting place for research and active discussions among hospitalists and patients. We invite you to be part of that discussion. https://www.choosingwisely.org/

CASE PRESENTATION

A 54‐year‐old woman presented to the emergency department (ED) with shortness of breath. She reported that her primary care physician diagnosed her with chronic obstructive pulmonary disease (COPD). Her physician had prescribed her an albuterol inhaler to use as needed for shortness of breath. Over the past few weeks she had been trying to use the inhaler, but she noted that it did not seem to help her increasing wheezing, coughing, and sputum production. In the ED, she received continuous albuterol treatments via nebulizer, Solu‐Medrol 125 mg intravenously, antibiotics, and a chest x‐ray. She was admitted to the hospital medicine service for COPD exacerbation and started on nebulized bronchodilator treatments every 4 hours. By the fourth day of her hospital stay, she was discharged to home with an albuterol inhaler, oral prednisone, oral doxycycline, and a follow‐up appointment. Dedicated patient education regarding proper inhaler administration did not occur during hospitalization.

WHY YOU MIGHT THINK NEBULIZED TREATMENTS IN INPATIENTS ARE HELPFUL

Inhaled bronchodilators are a mainstay of therapy for acute obstructive pulmonary diseases, including COPD and asthma exacerbations.[1, 2] Inhaled bronchodilators may be delivered by metered‐dose inhalers (MDIs) or via wet nebulizers powered by compressed air or oxygen. Current practice patterns in EDs and hospital wards tend to favor the use of nebulizers due to many apparent advantages of these devices.[3] For instance, nebulizers do not require any special inhalation technique and can be effectively used by patients at any age.[3, 4] There is also a common perception that nebulizers are more effective, possibly stemming from the assumption that hospitalized patients have already failed their outpatient MDI therapy and an almost mystical belief in the healing power of mist. Moreover, many clinicians have been trained to routinely use nebulizer therapies and may lack sufficient knowledge or comfort about the relative efficacy and equivalence dosing of MDI therapies.

WHY NEBULIZERS ARE NOT BETTER THAN MDIs FOR PATIENTS HOSPITALIZED WITH OBSTRUCTIVE PULMONARY SYMPTOMS

Decades of research support that MDIs are effective, efficient, and less costly (depending on circumstances) than nebulizers for the routine treatment of obstructive pulmonary exacerbations.[3, 4, 5, 6, 7, 8, 9, 10, 11] The clinical effectiveness of MDIs has been shown in studies across populations of adults with acute COPD symptoms,[3, 4, 7, 8] as well as children and adults with asthma exacerbations.[3, 4, 5, 6, 9, 10] A 2005 joint report by the American College of Chest Physicians (ACCP) and the American College of Asthma, Allergy and Immunology (ACAAI), concluded none of the pooled meta‐analyses showed a significant difference between devices in any efficacy outcome in any patient group for each of the clinical settings.[4] Many different outcomes have been investigated, including forced expiratory volumes (FEV), peak flows, symptoms and specific symptom scores, and physical findings.[4]

Compared to MDIs, there are a number of drawbacks to the use of nebulizers: nebulizers are more expensive to buy and maintain, are less portable, and take longer to set up, use, and clean following each use.[12] In addition, nebulizers have been associated with greater increases in heart rate and tremors compared to MDIs, suggesting nebulizers lead to higher systemically absorbed ‐agonist doses.[4]

Of note, nearly all of the clinical effectiveness studies administered MDIs with a valved holding chamber or spacer, facilitating the delivery of drug to the airways.[3, 4] Although valved holding chambers are commonly referred to as a spacer, a true spacer does not have a valve and is rarely used today.[12]

THE EVIDENCE EXAMINING NEBULIZERS VERSUS MDIs IN PATIENTS WITH ASTHMA OR COPD EXACERBATIONS

A 2013 Cochrane review sought to establish the relative efficacy of MDIs with holding chambers versus nebulizers for children and adults who presented to a community setting or emergency department with acute asthma.[6] The review included a total of 1897 children and 729 adults in 39 randomized controlled trials. The authors judged the overall evidence to be of moderate quality. Children with acute asthma treated with MDIs in the ED had shorter lengths of stay in the ED (70 minutes vs 103 minutes), similar peak flow and FEV measurements, lower heart rates, and less tremor compared to children treated with nebulizers.[5, 6] There were no significant differences found between devices for the treatment of adult patients with asthma.[6]

In a separate double‐blind, randomized, placebo‐controlled study evaluating albuterol administered by nebulizer versus MDI with spacer for children <2 years old presenting to an ED with wheezing, the use of MDIs with a spacer and facemask was equally efficacious and may have led to fewer hospital admissions.[10]

Mandelberg et al. performed a double‐blind, randomized, placebo‐controlled trial for unselected adult patients presenting to an ED with obstructive pulmonary symptoms.[8] Patients received either 2 puffs of a placebo MDI with a spacer along with nebulized salbutamol 0.5 mL in 1.5 mL saline solution (n=25), or a salbutamol MDI along with a nebulized placebo saline solution (n=25). Treatments were repeated every 15 minutes up to 3 times, unless side effects occurred. Spirometric measurements were performed following each treatment. No differences were seen between the groups at any point during the study period. The authors concluded, Even in the setting of the unselected group of patient referrals to the [Department of Emergency Medicine] for episodes of severe airflow limitation, the clinical and objective bronchodilator responses to the administration of salbutamol are independent of the method of delivery: MDI with large spacer or aerosol nebulization.[8]

There are surprisingly few studies examining the use of nebulizers versus MDIs in the inpatient setting for both children and adults. Dolovich et al. reviewed 6 studies that included 253 total patients and reported no significant differences in pulmonary function between devices.[4] Based on these findings, the ACCP/ACAAI group recommended both nebulizers and MDIs with spacers/holding chambers are appropriate for use in the inpatient setting. Quality of evidence: good.[4]

WHY USE MDIs FOR INPATIENTS

If MDI and nebulizer treatments are equally effective, why change current practice? The use of MDIs, rather than nebulizers, in hospitals could lead to fewer side effects such as tachycardia, arrhythmias, and tremors. MDIs are also more portable and do not require specialized set‐up. Furthermore, MDI administrations during hospitalization may provide a golden opportunity to have respiratory therapists, pharmacists, or other health professionals spend time teaching patients proper inhaler usage, rather than providing time‐consuming nebulizer treatments.[13] In a recent study, approximately 86% of hospitalized patients with asthma or COPD could not demonstrate appropriate use of an MDI. However, 100% of patients were able to achieve mastery following a short teach‐back session.[14] It is conceivable that transitioning patients to MDIs earlier during hospitalization and providing them with education regarding proper MDI administration could instill confidence in their use of inhalers and result in downstream effects such as shorter lengths of stay, less frequent hospital readmissions, or improved quality of life.

MDI use may result in cost savings in certain settings, although the relative costs of nebulizer versus MDI treatments depends on many institution‐specific factors. Such factors include the institutional policies on who delivers the nebulizer or the MDI and how they are compensated and staffed. For example in the Nebs No More After 24 program initiated at the University of California, San Francisco, the vast majority of the realized cost savings are due to the reduction in respiratory therapist time spent delivering MDIs, which reflects the local policies and compensation structure.[13] Previous inpatient interventions to convert from nebulizers to MDIs also showed cost savings resulting from decreased labor needs.[15] In some hospitals, nurses deliver nebulizer treatments, whereas in others only respiratory therapists are allowed to provide nebulizers. Moreover, whether the MDI can go home with the patient upon discharge depends on whether the hospital has a dispensing pharmacy or not. Formal economic evaluations specific to the local institution are necessary.

WHAT WE SHOULD DO INSTEAD: ENCOURAGE THE USE OF MDIs FOR INPATIENTS

For effective inpatient MDI treatments, MDI technique must be good. Thus, it is vital to enlist the right people to provide proper MDI teaching and supervision. Respiratory therapists are generally trained for this task, and may be complemented by appropriately trained physicians, nurses, or pharmacists. Many institutions have successfully implemented respiratory therapist‐driven protocols for the administration of MDIs, which has led to measurable improvements in the utilization of appropriate respiratory care resources.[15, 16] At University of California, San Francisco, this was accomplished by recruiting respiratory therapists and nurses to help support the transition of patients from nebulizers to MDIs and to provide bedside teaching on proper MDI usage. The institution then launched a Nebs No More After 24 campaign that sought to transition patients from nebulizers to MDIs within 24 hours of hospitalization. This campaign included an educational program for physicians, prepared facilitator guides to assist attending physicians with teaching about the new initiative, publicity efforts including pens and strategically placed posters, and regular feedback regarding nebulizer utilization on the pilot ward. Although the evidence suggests that patients can be started on MDIs immediately upon presentation to the ED, the UCSF campaign focused on transitioning patients within 24 hours so to alleviate concerns about transitions in care between the ED and the medical ward, as well as between overnight and day teams. MDIs are only as or more effective than nebulizers if the correct administration technique is employed. The 24‐hour transition period allows for MDI teaching and transition during regular daytime hours.

Inpatient use of nebulizers may be more appropriate than MDIs for patients with dementia or altered mental status, as well as those in extreme distress resulting in an inability to coordinate inhaler usage. Very low health literacy may be an additional barrier to appropriate MDI teaching and usage.

RECOMMENDATIONS

In patients with obstructive pulmonary symptoms, transition patients from nebulizers to MDIs early in their hospital course, unless the patient is unable to use an inhaler due to altered mental status, dementia, or other circumstances. Ensure that patients are instructed and supervised on proper MDI technique. Enlisting respiratory therapists and appropriately trained staff (pharmacists, nurses, physicians) is key to the successful use of MDIs. Frequency and dosage of MDIs used should be comparable to that of nebulized treatments. Although studies have used a relatively wide range of albuterol MDI dosing, prior programs have determined a dose of albuterol 4 puffs via MDI as being equivalent to the standard albuterol 2.5 mg nebulizer dosage.[17, 18] Some studies have advocated for using a range of 2 to 10 puffs albuterol MDI, with the actual dose based on clinical response.[17] One study in children with mild acute asthma found that 2 puffs of albuterol by MDI was just as effective as higher doses delivered by MDI (610 puffs) or by nebulizer.[19]

CONCLUSION

MDIs with holding chambers are clinically equivalent to nebulizer therapy for the treatment of both children and adults with obstructive pulmonary symptoms, as long as MDI technique and MDI dosing is adequate. This is based on good data in the ED setting but fewer studies in adult inpatients. There are a number of advantages to the use of inpatient MDIs over nebulizers; MDIs are more portable, often less expensive to use, may result in fewer side effects, and will hopefully improve outpatient MDI technique. The delivery of MDIs during hospitalization should be accompanied with patient education regarding proper administration technique.

Do you think this is a low‐value practice? Is this truly a Thing We Do for No Reason? Share what you do in your practice and join in the conversation online by retweeting it on Twitter (#TWDFNR) and Liking It on Facebook. We invite you to propose ideas for other Things We Do for No Reason topics by emailing [email protected]

The Things We Do for No Reason (TWDFNR) series reviews practices which have become common parts of hospital care but which may provide little value to our patients. Practices reviewed in the TWDFNR series do not represent black and white conclusions or clinical practice standards, but are meant as a starting place for research and active discussions among hospitalists and patients. We invite you to be part of that discussion. https://www.choosingwisely.org/

CASE PRESENTATION

A 54‐year‐old woman presented to the emergency department (ED) with shortness of breath. She reported that her primary care physician diagnosed her with chronic obstructive pulmonary disease (COPD). Her physician had prescribed her an albuterol inhaler to use as needed for shortness of breath. Over the past few weeks she had been trying to use the inhaler, but she noted that it did not seem to help her increasing wheezing, coughing, and sputum production. In the ED, she received continuous albuterol treatments via nebulizer, Solu‐Medrol 125 mg intravenously, antibiotics, and a chest x‐ray. She was admitted to the hospital medicine service for COPD exacerbation and started on nebulized bronchodilator treatments every 4 hours. By the fourth day of her hospital stay, she was discharged to home with an albuterol inhaler, oral prednisone, oral doxycycline, and a follow‐up appointment. Dedicated patient education regarding proper inhaler administration did not occur during hospitalization.

WHY YOU MIGHT THINK NEBULIZED TREATMENTS IN INPATIENTS ARE HELPFUL

Inhaled bronchodilators are a mainstay of therapy for acute obstructive pulmonary diseases, including COPD and asthma exacerbations.[1, 2] Inhaled bronchodilators may be delivered by metered‐dose inhalers (MDIs) or via wet nebulizers powered by compressed air or oxygen. Current practice patterns in EDs and hospital wards tend to favor the use of nebulizers due to many apparent advantages of these devices.[3] For instance, nebulizers do not require any special inhalation technique and can be effectively used by patients at any age.[3, 4] There is also a common perception that nebulizers are more effective, possibly stemming from the assumption that hospitalized patients have already failed their outpatient MDI therapy and an almost mystical belief in the healing power of mist. Moreover, many clinicians have been trained to routinely use nebulizer therapies and may lack sufficient knowledge or comfort about the relative efficacy and equivalence dosing of MDI therapies.

WHY NEBULIZERS ARE NOT BETTER THAN MDIs FOR PATIENTS HOSPITALIZED WITH OBSTRUCTIVE PULMONARY SYMPTOMS

Decades of research support that MDIs are effective, efficient, and less costly (depending on circumstances) than nebulizers for the routine treatment of obstructive pulmonary exacerbations.[3, 4, 5, 6, 7, 8, 9, 10, 11] The clinical effectiveness of MDIs has been shown in studies across populations of adults with acute COPD symptoms,[3, 4, 7, 8] as well as children and adults with asthma exacerbations.[3, 4, 5, 6, 9, 10] A 2005 joint report by the American College of Chest Physicians (ACCP) and the American College of Asthma, Allergy and Immunology (ACAAI), concluded none of the pooled meta‐analyses showed a significant difference between devices in any efficacy outcome in any patient group for each of the clinical settings.[4] Many different outcomes have been investigated, including forced expiratory volumes (FEV), peak flows, symptoms and specific symptom scores, and physical findings.[4]

Compared to MDIs, there are a number of drawbacks to the use of nebulizers: nebulizers are more expensive to buy and maintain, are less portable, and take longer to set up, use, and clean following each use.[12] In addition, nebulizers have been associated with greater increases in heart rate and tremors compared to MDIs, suggesting nebulizers lead to higher systemically absorbed ‐agonist doses.[4]

Of note, nearly all of the clinical effectiveness studies administered MDIs with a valved holding chamber or spacer, facilitating the delivery of drug to the airways.[3, 4] Although valved holding chambers are commonly referred to as a spacer, a true spacer does not have a valve and is rarely used today.[12]

THE EVIDENCE EXAMINING NEBULIZERS VERSUS MDIs IN PATIENTS WITH ASTHMA OR COPD EXACERBATIONS

A 2013 Cochrane review sought to establish the relative efficacy of MDIs with holding chambers versus nebulizers for children and adults who presented to a community setting or emergency department with acute asthma.[6] The review included a total of 1897 children and 729 adults in 39 randomized controlled trials. The authors judged the overall evidence to be of moderate quality. Children with acute asthma treated with MDIs in the ED had shorter lengths of stay in the ED (70 minutes vs 103 minutes), similar peak flow and FEV measurements, lower heart rates, and less tremor compared to children treated with nebulizers.[5, 6] There were no significant differences found between devices for the treatment of adult patients with asthma.[6]

In a separate double‐blind, randomized, placebo‐controlled study evaluating albuterol administered by nebulizer versus MDI with spacer for children <2 years old presenting to an ED with wheezing, the use of MDIs with a spacer and facemask was equally efficacious and may have led to fewer hospital admissions.[10]

Mandelberg et al. performed a double‐blind, randomized, placebo‐controlled trial for unselected adult patients presenting to an ED with obstructive pulmonary symptoms.[8] Patients received either 2 puffs of a placebo MDI with a spacer along with nebulized salbutamol 0.5 mL in 1.5 mL saline solution (n=25), or a salbutamol MDI along with a nebulized placebo saline solution (n=25). Treatments were repeated every 15 minutes up to 3 times, unless side effects occurred. Spirometric measurements were performed following each treatment. No differences were seen between the groups at any point during the study period. The authors concluded, Even in the setting of the unselected group of patient referrals to the [Department of Emergency Medicine] for episodes of severe airflow limitation, the clinical and objective bronchodilator responses to the administration of salbutamol are independent of the method of delivery: MDI with large spacer or aerosol nebulization.[8]

There are surprisingly few studies examining the use of nebulizers versus MDIs in the inpatient setting for both children and adults. Dolovich et al. reviewed 6 studies that included 253 total patients and reported no significant differences in pulmonary function between devices.[4] Based on these findings, the ACCP/ACAAI group recommended both nebulizers and MDIs with spacers/holding chambers are appropriate for use in the inpatient setting. Quality of evidence: good.[4]

WHY USE MDIs FOR INPATIENTS

If MDI and nebulizer treatments are equally effective, why change current practice? The use of MDIs, rather than nebulizers, in hospitals could lead to fewer side effects such as tachycardia, arrhythmias, and tremors. MDIs are also more portable and do not require specialized set‐up. Furthermore, MDI administrations during hospitalization may provide a golden opportunity to have respiratory therapists, pharmacists, or other health professionals spend time teaching patients proper inhaler usage, rather than providing time‐consuming nebulizer treatments.[13] In a recent study, approximately 86% of hospitalized patients with asthma or COPD could not demonstrate appropriate use of an MDI. However, 100% of patients were able to achieve mastery following a short teach‐back session.[14] It is conceivable that transitioning patients to MDIs earlier during hospitalization and providing them with education regarding proper MDI administration could instill confidence in their use of inhalers and result in downstream effects such as shorter lengths of stay, less frequent hospital readmissions, or improved quality of life.

MDI use may result in cost savings in certain settings, although the relative costs of nebulizer versus MDI treatments depends on many institution‐specific factors. Such factors include the institutional policies on who delivers the nebulizer or the MDI and how they are compensated and staffed. For example in the Nebs No More After 24 program initiated at the University of California, San Francisco, the vast majority of the realized cost savings are due to the reduction in respiratory therapist time spent delivering MDIs, which reflects the local policies and compensation structure.[13] Previous inpatient interventions to convert from nebulizers to MDIs also showed cost savings resulting from decreased labor needs.[15] In some hospitals, nurses deliver nebulizer treatments, whereas in others only respiratory therapists are allowed to provide nebulizers. Moreover, whether the MDI can go home with the patient upon discharge depends on whether the hospital has a dispensing pharmacy or not. Formal economic evaluations specific to the local institution are necessary.

WHAT WE SHOULD DO INSTEAD: ENCOURAGE THE USE OF MDIs FOR INPATIENTS

For effective inpatient MDI treatments, MDI technique must be good. Thus, it is vital to enlist the right people to provide proper MDI teaching and supervision. Respiratory therapists are generally trained for this task, and may be complemented by appropriately trained physicians, nurses, or pharmacists. Many institutions have successfully implemented respiratory therapist‐driven protocols for the administration of MDIs, which has led to measurable improvements in the utilization of appropriate respiratory care resources.[15, 16] At University of California, San Francisco, this was accomplished by recruiting respiratory therapists and nurses to help support the transition of patients from nebulizers to MDIs and to provide bedside teaching on proper MDI usage. The institution then launched a Nebs No More After 24 campaign that sought to transition patients from nebulizers to MDIs within 24 hours of hospitalization. This campaign included an educational program for physicians, prepared facilitator guides to assist attending physicians with teaching about the new initiative, publicity efforts including pens and strategically placed posters, and regular feedback regarding nebulizer utilization on the pilot ward. Although the evidence suggests that patients can be started on MDIs immediately upon presentation to the ED, the UCSF campaign focused on transitioning patients within 24 hours so to alleviate concerns about transitions in care between the ED and the medical ward, as well as between overnight and day teams. MDIs are only as or more effective than nebulizers if the correct administration technique is employed. The 24‐hour transition period allows for MDI teaching and transition during regular daytime hours.

Inpatient use of nebulizers may be more appropriate than MDIs for patients with dementia or altered mental status, as well as those in extreme distress resulting in an inability to coordinate inhaler usage. Very low health literacy may be an additional barrier to appropriate MDI teaching and usage.

RECOMMENDATIONS

In patients with obstructive pulmonary symptoms, transition patients from nebulizers to MDIs early in their hospital course, unless the patient is unable to use an inhaler due to altered mental status, dementia, or other circumstances. Ensure that patients are instructed and supervised on proper MDI technique. Enlisting respiratory therapists and appropriately trained staff (pharmacists, nurses, physicians) is key to the successful use of MDIs. Frequency and dosage of MDIs used should be comparable to that of nebulized treatments. Although studies have used a relatively wide range of albuterol MDI dosing, prior programs have determined a dose of albuterol 4 puffs via MDI as being equivalent to the standard albuterol 2.5 mg nebulizer dosage.[17, 18] Some studies have advocated for using a range of 2 to 10 puffs albuterol MDI, with the actual dose based on clinical response.[17] One study in children with mild acute asthma found that 2 puffs of albuterol by MDI was just as effective as higher doses delivered by MDI (610 puffs) or by nebulizer.[19]

CONCLUSION

MDIs with holding chambers are clinically equivalent to nebulizer therapy for the treatment of both children and adults with obstructive pulmonary symptoms, as long as MDI technique and MDI dosing is adequate. This is based on good data in the ED setting but fewer studies in adult inpatients. There are a number of advantages to the use of inpatient MDIs over nebulizers; MDIs are more portable, often less expensive to use, may result in fewer side effects, and will hopefully improve outpatient MDI technique. The delivery of MDIs during hospitalization should be accompanied with patient education regarding proper administration technique.

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Readmissions of Medicare beneficiaries within 30 days of discharge are frequent and costly.[1] Concern about readmissions has prompted the Centers for Medicare & Medicaid Services (CMS) to reduce payments to hospitals with excess readmissions.[2] Research has identified a number of patient clinical and socio‐demographic factors associated with readmissions.[3] However, interventions designed to reduce readmissions have met with limited success. In a systematic review, no single intervention was regularly effective in reducing readmissions, despite the fact that interventions have targeted both predischarge, transition of care, and postdischarge processes of care.[4]

The different trajectories of care experienced by patients after hospital discharge, and their effect on risk of readmission, have been incompletely studied. Although early outpatient follow‐up after discharge is associated with lower readmission rates,[5, 6] a factor that has been minimally studied is the role of the emergency department (ED) and the ED provider in readmissions. The ED and ED providers feature prominently in the care received by patients shortly after discharge from a hospital. About a quarter of all hospitalized Medicare patients are evaluated in an ED within 30 days of discharge,[7, 8] and a majority of readmissions within 30 days of discharge are precipitated by an ED visit.[9] Hence, we asked whether when a recently discharged patient is seen in an ED, does the rate of readmission vary by ED provider and by ED facility?

We used Texas Medicare claims data to examine patients visiting the ED within 30 days of discharge from an initial hospitalization to determine if their risk of readmission varies by the ED provider caring for them and by the ED facility they visit.

METHODS

RESULTS

We identified 174,209 patients who visited an ED within 30 days of discharge from an initial hospitalization. Table 1 describes the characteristics of these patients as well as the readmission rates associated with these characteristics. The rate of readmission of our cohort of 1,627,705 discharges with or without a following ED visit was 16.2%, whereas the rate of readmission following an ED visit in our final cohort of 174,209 patients was 52.67%. This readmission rate increased with age, from 49.31% for patients between 66 and 70 years of age to 55.33% for patients older than 85 years. There were minor variations by gender and ethnicity. Patients residing in metropolitan areas or in zip codes with low education levels had higher readmission rates, as did those whose original admission was classified as emergency or those who were not discharged home.

Table 1 also presents the odds of readmission adjusted for all other factors in the table and also adjusted for clustering within ED providers in a 2‐level model. Increasing age, white race, metropolitan residence, nonhome discharge, higher severity of illness, more hospitalizations in the prior year, fewer physician visits in the prior year, and an emergency initial admission were each associated with a higher readmission rate.

We next generated estimates of readmission rates for each ED provider from the adjusted 2‐level models. Figure 1 shows the adjusted cumulative readmission rates for the 1922 ED providers. This figure shows the mean value and 95% confidence intervals of the readmission rates for each provider. Dark vertical lines indicate providers whose readmission rate differed significantly from the mean adjusted readmission rate of 52.1% for all providers. Of the ED providers, 14.2% had significantly higher readmission rates. The mean readmission rate for these 272 providers was 67.2%. Of the ED providers, 14.7% had significantly lower readmission rates. The mean readmission rate for these 283 providers was 36.8%.

Figure 1

To determine the contribution of the ED facility to the variation in readmission rates, we restricted our analysis to 48,883 patients (28.06% of our cohort) seen by 525 ED providers who were associated with only 1 facility (total of 143 facilities). Table 2 describes the unadjusted readmission rates stratified by specific characteristics of those facilities. The unadjusted readmission rate increased with the size of the associated hospital, from 47.61% for hospitals with less than 100 beds to 57.06% for hospitals with more than 400 beds. The readmission rate for nonprofit facilities was 53.81% and for for‐profit facilities was 57.39%. Facilities with no medical school affiliation had a readmission rate of 54.51%, whereas those with a major affiliation had a readmission rate of 58.72%.

With this smaller cohort, we performed 2 types of 2‐level models, where patients clustered within ED facilities and ER providers, respectively, and a 3‐level model accounting for clustering of patients within providers and of providers within facilities. From the facility‐patient 2‐level model, the variance of the ED facility was 0.2718 (95% confidence interval [CI]: 0.2083‐0.3696). From the provider‐patient 2‐level model, the variance of ED provider was 0.2532 (95% CI: 0.2166‐0.3002). However, when the 3‐level model was performed, the variance of ED provider decreased to 0.0893 (95% CI: 0.0723‐0.1132) and the variance of ED facility dropped to 0.2316 (95% CI: 0.1704‐0.3331) . This indicates 65% of the variation among ED providers was explained by the ED facility, and in contrast, 15% of the variation among ED facilities was explained by ED providers.

Table 2 also shows the adjusted odds of readmission generated from the 3‐level model. Patients receiving care in ED facilities in hospitals with more beds and in for‐profit hospitals were at higher risk for readmission. It is possible that patients seen at the ED associated with the discharging hospital had a lower risk of readmission. This finding was close to being statistically significant (P=0.051).

We repeated all the above analyses using an outcome of readmission anytime between the ED visit and 30 days after discharge from the initial hospitalization (rather than readmission on the day of or after the ED visit). All analyses produced results similar to the results presented above. For example, Figure 2 shows the adjusted cumulative readmission rates for the 1922 ED providers using this outcome. Of the ED providers, 12.8% had higher and 12.5% had lower readmission rates as compared to the mean readmission rate for all ED providers. The Spearman correlation coefficient between the rank of ED providers in immediate readmission rate (Figure 1) and readmission rate within 30 days of hospital discharge (Figure 2) was 0.94 (P<0.001).

Figure 2

DISCUSSION

This study found substantial variation in readmission rates by ED provider, despite controlling for patient clinical and sociodemographic factors. In 3‐level models, the ED facility explained a substantial part of the variation by ED provider, with patients seen at larger facilities and for‐profit facilities having higher readmission rates.

Variation among ED facilities and ED providers in readmission rates has not previously been studied. There is literature on the variation in ED facility and ED provider admission rates. As readmissions are a subset of all admissions, this literature provides context to our findings. Abualenain et al. examined admission rates for 89 ED physicians for adult patients presenting with an acute medical or surgical complaint at 3 EDs in a health system.[12] After adjusting for patient and clinical characteristics, admission rates varied from 21% to 49% among physicians and from 27% to 41% among 3 facilities. Two other studies from single hospitals have found similar variation among providers.[13, 14] The reasons for the variation among ED providers presumably relate to subjective aspects of clinical assessment and the reluctance of providers to rely solely on objective scales, even when they are available.[14, 15] Variation in admission rates among different facilities may relate to clustering of providers with similar practice styles within facilities, lack of clinical guidelines for certain conditions, as well as differences among facilities in the socioeconomic status and access to primary care of their clientele.[12, 16, 17] For example, Pines et al. have shown that ED facility admission rates are higher in communities with fewer primary care physicians per capita and are influenced by the prevailing county level admission rates.[16] Capp et al. showed persistent variation in admission rates across hospitals, despite adjusting for clinical criteria such as vital signs, chief complaints, and severity of illness.[18]

Structural differences in ED facilities may also influence the decision to admit. We found that patients visiting ED facilities in hospitals with more beds had a higher readmission rate. ED facility systems of care such as observation units or protocols are associated with lower admission rates.[19, 20] Finally, certain hospitals may actively influence the admission practice patterns of their ED providers. We noted that patients seen at for‐profit ED facilities had a greater risk of readmission. A similar finding has been described by Pines et al., who noted higher admission rates at for‐profit facilities.[16] In an extreme example, a recent Justice Department lawsuit alleged that a for‐profit hospital chain used software systems and financial incentives to ED providers to increase admissions.[21]

It is possible that the providers with low readmission rates may have inappropriately released patients who truly should have been admitted. A signal that this occurred would be if these patients were readmitted in the days after the ED visits. We examined this possibility by additionally examining readmissions occurring anytime between the ED visit until 30 days after discharge from the initial hospitalization. The results were similar to when we only included readmissions that occurred immediately following the ED visit, with a very high correlation (r=0.94) between the ranking of the ED providers by readmission rates in both circumstances. This suggests that the decisions of the ED providers with low readmission rates to admit or release from the ED were likely appropriate.

Our research has limitations. We studied patients with fee‐for‐service Medicare in a single large state in the United States over a 4‐year period. Our findings may not be generalizable to younger patient populations, other regions with different sociodemographic patterns and healthcare systems, or other time periods. We could not control for many factors that may impact the risk of readmission but are not measured in Medicare databases (eg, clinical data such as vital signs, measures of quality of transition from discharging hospital, ED provider workload). To attribute care to a single ED provider, we excluded patients who were taken care of by multiple ED providers. These patients may have different needs from our study population (eg, more complex issues and longer stays in the ED) and may bias our results.

This study provides a new direction for research and quality improvement targeting readmissions. Research should extend beyond the discharge transition and examine the entire trajectory of posthospitalization care to better understand readmissions. Based directly on this study, research could investigate the practice patterns of ED providers and systems of care at ED facilities that affect readmissions rates. Such investigation could inform quality improvement efforts to standardize care for patients in the ED.

CMS policies hold hospitals accountable for readmissions of the patients they discharge, but do not address the admission process in the ED that leads to readmissions of recently discharged patients. Given the present study, and the fact that the proportion of all hospital admissions that occur through the ED has grown to 44%,[22] consideration of the role of the ED in public policy efforts to discourage unnecessary inpatient care may be appropriate.

In summary, this study shows that a recently discharged patient's chances of being readmitted depends partly on the ED provider who evaluates them and on the ED facility at which they seek care. ED provider practice patterns and ED facility systems of care may be a target for interventions aimed at decreasing readmission rates.

Readmissions of Medicare beneficiaries within 30 days of discharge are frequent and costly.[1] Concern about readmissions has prompted the Centers for Medicare & Medicaid Services (CMS) to reduce payments to hospitals with excess readmissions.[2] Research has identified a number of patient clinical and socio‐demographic factors associated with readmissions.[3] However, interventions designed to reduce readmissions have met with limited success. In a systematic review, no single intervention was regularly effective in reducing readmissions, despite the fact that interventions have targeted both predischarge, transition of care, and postdischarge processes of care.[4]

The different trajectories of care experienced by patients after hospital discharge, and their effect on risk of readmission, have been incompletely studied. Although early outpatient follow‐up after discharge is associated with lower readmission rates,[5, 6] a factor that has been minimally studied is the role of the emergency department (ED) and the ED provider in readmissions. The ED and ED providers feature prominently in the care received by patients shortly after discharge from a hospital. About a quarter of all hospitalized Medicare patients are evaluated in an ED within 30 days of discharge,[7, 8] and a majority of readmissions within 30 days of discharge are precipitated by an ED visit.[9] Hence, we asked whether when a recently discharged patient is seen in an ED, does the rate of readmission vary by ED provider and by ED facility?

We used Texas Medicare claims data to examine patients visiting the ED within 30 days of discharge from an initial hospitalization to determine if their risk of readmission varies by the ED provider caring for them and by the ED facility they visit.

METHODS

RESULTS

We identified 174,209 patients who visited an ED within 30 days of discharge from an initial hospitalization. Table 1 describes the characteristics of these patients as well as the readmission rates associated with these characteristics. The rate of readmission of our cohort of 1,627,705 discharges with or without a following ED visit was 16.2%, whereas the rate of readmission following an ED visit in our final cohort of 174,209 patients was 52.67%. This readmission rate increased with age, from 49.31% for patients between 66 and 70 years of age to 55.33% for patients older than 85 years. There were minor variations by gender and ethnicity. Patients residing in metropolitan areas or in zip codes with low education levels had higher readmission rates, as did those whose original admission was classified as emergency or those who were not discharged home.

Table 1 also presents the odds of readmission adjusted for all other factors in the table and also adjusted for clustering within ED providers in a 2‐level model. Increasing age, white race, metropolitan residence, nonhome discharge, higher severity of illness, more hospitalizations in the prior year, fewer physician visits in the prior year, and an emergency initial admission were each associated with a higher readmission rate.

We next generated estimates of readmission rates for each ED provider from the adjusted 2‐level models. Figure 1 shows the adjusted cumulative readmission rates for the 1922 ED providers. This figure shows the mean value and 95% confidence intervals of the readmission rates for each provider. Dark vertical lines indicate providers whose readmission rate differed significantly from the mean adjusted readmission rate of 52.1% for all providers. Of the ED providers, 14.2% had significantly higher readmission rates. The mean readmission rate for these 272 providers was 67.2%. Of the ED providers, 14.7% had significantly lower readmission rates. The mean readmission rate for these 283 providers was 36.8%.

Figure 1

To determine the contribution of the ED facility to the variation in readmission rates, we restricted our analysis to 48,883 patients (28.06% of our cohort) seen by 525 ED providers who were associated with only 1 facility (total of 143 facilities). Table 2 describes the unadjusted readmission rates stratified by specific characteristics of those facilities. The unadjusted readmission rate increased with the size of the associated hospital, from 47.61% for hospitals with less than 100 beds to 57.06% for hospitals with more than 400 beds. The readmission rate for nonprofit facilities was 53.81% and for for‐profit facilities was 57.39%. Facilities with no medical school affiliation had a readmission rate of 54.51%, whereas those with a major affiliation had a readmission rate of 58.72%.

With this smaller cohort, we performed 2 types of 2‐level models, where patients clustered within ED facilities and ER providers, respectively, and a 3‐level model accounting for clustering of patients within providers and of providers within facilities. From the facility‐patient 2‐level model, the variance of the ED facility was 0.2718 (95% confidence interval [CI]: 0.2083‐0.3696). From the provider‐patient 2‐level model, the variance of ED provider was 0.2532 (95% CI: 0.2166‐0.3002). However, when the 3‐level model was performed, the variance of ED provider decreased to 0.0893 (95% CI: 0.0723‐0.1132) and the variance of ED facility dropped to 0.2316 (95% CI: 0.1704‐0.3331) . This indicates 65% of the variation among ED providers was explained by the ED facility, and in contrast, 15% of the variation among ED facilities was explained by ED providers.

Table 2 also shows the adjusted odds of readmission generated from the 3‐level model. Patients receiving care in ED facilities in hospitals with more beds and in for‐profit hospitals were at higher risk for readmission. It is possible that patients seen at the ED associated with the discharging hospital had a lower risk of readmission. This finding was close to being statistically significant (P=0.051).

We repeated all the above analyses using an outcome of readmission anytime between the ED visit and 30 days after discharge from the initial hospitalization (rather than readmission on the day of or after the ED visit). All analyses produced results similar to the results presented above. For example, Figure 2 shows the adjusted cumulative readmission rates for the 1922 ED providers using this outcome. Of the ED providers, 12.8% had higher and 12.5% had lower readmission rates as compared to the mean readmission rate for all ED providers. The Spearman correlation coefficient between the rank of ED providers in immediate readmission rate (Figure 1) and readmission rate within 30 days of hospital discharge (Figure 2) was 0.94 (P<0.001).

Figure 2

DISCUSSION

This study found substantial variation in readmission rates by ED provider, despite controlling for patient clinical and sociodemographic factors. In 3‐level models, the ED facility explained a substantial part of the variation by ED provider, with patients seen at larger facilities and for‐profit facilities having higher readmission rates.

Variation among ED facilities and ED providers in readmission rates has not previously been studied. There is literature on the variation in ED facility and ED provider admission rates. As readmissions are a subset of all admissions, this literature provides context to our findings. Abualenain et al. examined admission rates for 89 ED physicians for adult patients presenting with an acute medical or surgical complaint at 3 EDs in a health system.[12] After adjusting for patient and clinical characteristics, admission rates varied from 21% to 49% among physicians and from 27% to 41% among 3 facilities. Two other studies from single hospitals have found similar variation among providers.[13, 14] The reasons for the variation among ED providers presumably relate to subjective aspects of clinical assessment and the reluctance of providers to rely solely on objective scales, even when they are available.[14, 15] Variation in admission rates among different facilities may relate to clustering of providers with similar practice styles within facilities, lack of clinical guidelines for certain conditions, as well as differences among facilities in the socioeconomic status and access to primary care of their clientele.[12, 16, 17] For example, Pines et al. have shown that ED facility admission rates are higher in communities with fewer primary care physicians per capita and are influenced by the prevailing county level admission rates.[16] Capp et al. showed persistent variation in admission rates across hospitals, despite adjusting for clinical criteria such as vital signs, chief complaints, and severity of illness.[18]

Structural differences in ED facilities may also influence the decision to admit. We found that patients visiting ED facilities in hospitals with more beds had a higher readmission rate. ED facility systems of care such as observation units or protocols are associated with lower admission rates.[19, 20] Finally, certain hospitals may actively influence the admission practice patterns of their ED providers. We noted that patients seen at for‐profit ED facilities had a greater risk of readmission. A similar finding has been described by Pines et al., who noted higher admission rates at for‐profit facilities.[16] In an extreme example, a recent Justice Department lawsuit alleged that a for‐profit hospital chain used software systems and financial incentives to ED providers to increase admissions.[21]

It is possible that the providers with low readmission rates may have inappropriately released patients who truly should have been admitted. A signal that this occurred would be if these patients were readmitted in the days after the ED visits. We examined this possibility by additionally examining readmissions occurring anytime between the ED visit until 30 days after discharge from the initial hospitalization. The results were similar to when we only included readmissions that occurred immediately following the ED visit, with a very high correlation (r=0.94) between the ranking of the ED providers by readmission rates in both circumstances. This suggests that the decisions of the ED providers with low readmission rates to admit or release from the ED were likely appropriate.

Our research has limitations. We studied patients with fee‐for‐service Medicare in a single large state in the United States over a 4‐year period. Our findings may not be generalizable to younger patient populations, other regions with different sociodemographic patterns and healthcare systems, or other time periods. We could not control for many factors that may impact the risk of readmission but are not measured in Medicare databases (eg, clinical data such as vital signs, measures of quality of transition from discharging hospital, ED provider workload). To attribute care to a single ED provider, we excluded patients who were taken care of by multiple ED providers. These patients may have different needs from our study population (eg, more complex issues and longer stays in the ED) and may bias our results.

This study provides a new direction for research and quality improvement targeting readmissions. Research should extend beyond the discharge transition and examine the entire trajectory of posthospitalization care to better understand readmissions. Based directly on this study, research could investigate the practice patterns of ED providers and systems of care at ED facilities that affect readmissions rates. Such investigation could inform quality improvement efforts to standardize care for patients in the ED.

CMS policies hold hospitals accountable for readmissions of the patients they discharge, but do not address the admission process in the ED that leads to readmissions of recently discharged patients. Given the present study, and the fact that the proportion of all hospital admissions that occur through the ED has grown to 44%,[22] consideration of the role of the ED in public policy efforts to discourage unnecessary inpatient care may be appropriate.

In summary, this study shows that a recently discharged patient's chances of being readmitted depends partly on the ED provider who evaluates them and on the ED facility at which they seek care. ED provider practice patterns and ED facility systems of care may be a target for interventions aimed at decreasing readmission rates.

Readmissions of Medicare beneficiaries within 30 days of discharge are frequent and costly.[1] Concern about readmissions has prompted the Centers for Medicare & Medicaid Services (CMS) to reduce payments to hospitals with excess readmissions.[2] Research has identified a number of patient clinical and socio‐demographic factors associated with readmissions.[3] However, interventions designed to reduce readmissions have met with limited success. In a systematic review, no single intervention was regularly effective in reducing readmissions, despite the fact that interventions have targeted both predischarge, transition of care, and postdischarge processes of care.[4]

The different trajectories of care experienced by patients after hospital discharge, and their effect on risk of readmission, have been incompletely studied. Although early outpatient follow‐up after discharge is associated with lower readmission rates,[5, 6] a factor that has been minimally studied is the role of the emergency department (ED) and the ED provider in readmissions. The ED and ED providers feature prominently in the care received by patients shortly after discharge from a hospital. About a quarter of all hospitalized Medicare patients are evaluated in an ED within 30 days of discharge,[7, 8] and a majority of readmissions within 30 days of discharge are precipitated by an ED visit.[9] Hence, we asked whether when a recently discharged patient is seen in an ED, does the rate of readmission vary by ED provider and by ED facility?

We used Texas Medicare claims data to examine patients visiting the ED within 30 days of discharge from an initial hospitalization to determine if their risk of readmission varies by the ED provider caring for them and by the ED facility they visit.

METHODS

RESULTS

We identified 174,209 patients who visited an ED within 30 days of discharge from an initial hospitalization. Table 1 describes the characteristics of these patients as well as the readmission rates associated with these characteristics. The rate of readmission of our cohort of 1,627,705 discharges with or without a following ED visit was 16.2%, whereas the rate of readmission following an ED visit in our final cohort of 174,209 patients was 52.67%. This readmission rate increased with age, from 49.31% for patients between 66 and 70 years of age to 55.33% for patients older than 85 years. There were minor variations by gender and ethnicity. Patients residing in metropolitan areas or in zip codes with low education levels had higher readmission rates, as did those whose original admission was classified as emergency or those who were not discharged home.

Table 1 also presents the odds of readmission adjusted for all other factors in the table and also adjusted for clustering within ED providers in a 2‐level model. Increasing age, white race, metropolitan residence, nonhome discharge, higher severity of illness, more hospitalizations in the prior year, fewer physician visits in the prior year, and an emergency initial admission were each associated with a higher readmission rate.

We next generated estimates of readmission rates for each ED provider from the adjusted 2‐level models. Figure 1 shows the adjusted cumulative readmission rates for the 1922 ED providers. This figure shows the mean value and 95% confidence intervals of the readmission rates for each provider. Dark vertical lines indicate providers whose readmission rate differed significantly from the mean adjusted readmission rate of 52.1% for all providers. Of the ED providers, 14.2% had significantly higher readmission rates. The mean readmission rate for these 272 providers was 67.2%. Of the ED providers, 14.7% had significantly lower readmission rates. The mean readmission rate for these 283 providers was 36.8%.

Figure 1

To determine the contribution of the ED facility to the variation in readmission rates, we restricted our analysis to 48,883 patients (28.06% of our cohort) seen by 525 ED providers who were associated with only 1 facility (total of 143 facilities). Table 2 describes the unadjusted readmission rates stratified by specific characteristics of those facilities. The unadjusted readmission rate increased with the size of the associated hospital, from 47.61% for hospitals with less than 100 beds to 57.06% for hospitals with more than 400 beds. The readmission rate for nonprofit facilities was 53.81% and for for‐profit facilities was 57.39%. Facilities with no medical school affiliation had a readmission rate of 54.51%, whereas those with a major affiliation had a readmission rate of 58.72%.

With this smaller cohort, we performed 2 types of 2‐level models, where patients clustered within ED facilities and ER providers, respectively, and a 3‐level model accounting for clustering of patients within providers and of providers within facilities. From the facility‐patient 2‐level model, the variance of the ED facility was 0.2718 (95% confidence interval [CI]: 0.2083‐0.3696). From the provider‐patient 2‐level model, the variance of ED provider was 0.2532 (95% CI: 0.2166‐0.3002). However, when the 3‐level model was performed, the variance of ED provider decreased to 0.0893 (95% CI: 0.0723‐0.1132) and the variance of ED facility dropped to 0.2316 (95% CI: 0.1704‐0.3331) . This indicates 65% of the variation among ED providers was explained by the ED facility, and in contrast, 15% of the variation among ED facilities was explained by ED providers.

Table 2 also shows the adjusted odds of readmission generated from the 3‐level model. Patients receiving care in ED facilities in hospitals with more beds and in for‐profit hospitals were at higher risk for readmission. It is possible that patients seen at the ED associated with the discharging hospital had a lower risk of readmission. This finding was close to being statistically significant (P=0.051).

We repeated all the above analyses using an outcome of readmission anytime between the ED visit and 30 days after discharge from the initial hospitalization (rather than readmission on the day of or after the ED visit). All analyses produced results similar to the results presented above. For example, Figure 2 shows the adjusted cumulative readmission rates for the 1922 ED providers using this outcome. Of the ED providers, 12.8% had higher and 12.5% had lower readmission rates as compared to the mean readmission rate for all ED providers. The Spearman correlation coefficient between the rank of ED providers in immediate readmission rate (Figure 1) and readmission rate within 30 days of hospital discharge (Figure 2) was 0.94 (P<0.001).

Figure 2

DISCUSSION

This study found substantial variation in readmission rates by ED provider, despite controlling for patient clinical and sociodemographic factors. In 3‐level models, the ED facility explained a substantial part of the variation by ED provider, with patients seen at larger facilities and for‐profit facilities having higher readmission rates.

Variation among ED facilities and ED providers in readmission rates has not previously been studied. There is literature on the variation in ED facility and ED provider admission rates. As readmissions are a subset of all admissions, this literature provides context to our findings. Abualenain et al. examined admission rates for 89 ED physicians for adult patients presenting with an acute medical or surgical complaint at 3 EDs in a health system.[12] After adjusting for patient and clinical characteristics, admission rates varied from 21% to 49% among physicians and from 27% to 41% among 3 facilities. Two other studies from single hospitals have found similar variation among providers.[13, 14] The reasons for the variation among ED providers presumably relate to subjective aspects of clinical assessment and the reluctance of providers to rely solely on objective scales, even when they are available.[14, 15] Variation in admission rates among different facilities may relate to clustering of providers with similar practice styles within facilities, lack of clinical guidelines for certain conditions, as well as differences among facilities in the socioeconomic status and access to primary care of their clientele.[12, 16, 17] For example, Pines et al. have shown that ED facility admission rates are higher in communities with fewer primary care physicians per capita and are influenced by the prevailing county level admission rates.[16] Capp et al. showed persistent variation in admission rates across hospitals, despite adjusting for clinical criteria such as vital signs, chief complaints, and severity of illness.[18]

Structural differences in ED facilities may also influence the decision to admit. We found that patients visiting ED facilities in hospitals with more beds had a higher readmission rate. ED facility systems of care such as observation units or protocols are associated with lower admission rates.[19, 20] Finally, certain hospitals may actively influence the admission practice patterns of their ED providers. We noted that patients seen at for‐profit ED facilities had a greater risk of readmission. A similar finding has been described by Pines et al., who noted higher admission rates at for‐profit facilities.[16] In an extreme example, a recent Justice Department lawsuit alleged that a for‐profit hospital chain used software systems and financial incentives to ED providers to increase admissions.[21]

It is possible that the providers with low readmission rates may have inappropriately released patients who truly should have been admitted. A signal that this occurred would be if these patients were readmitted in the days after the ED visits. We examined this possibility by additionally examining readmissions occurring anytime between the ED visit until 30 days after discharge from the initial hospitalization. The results were similar to when we only included readmissions that occurred immediately following the ED visit, with a very high correlation (r=0.94) between the ranking of the ED providers by readmission rates in both circumstances. This suggests that the decisions of the ED providers with low readmission rates to admit or release from the ED were likely appropriate.

Our research has limitations. We studied patients with fee‐for‐service Medicare in a single large state in the United States over a 4‐year period. Our findings may not be generalizable to younger patient populations, other regions with different sociodemographic patterns and healthcare systems, or other time periods. We could not control for many factors that may impact the risk of readmission but are not measured in Medicare databases (eg, clinical data such as vital signs, measures of quality of transition from discharging hospital, ED provider workload). To attribute care to a single ED provider, we excluded patients who were taken care of by multiple ED providers. These patients may have different needs from our study population (eg, more complex issues and longer stays in the ED) and may bias our results.

This study provides a new direction for research and quality improvement targeting readmissions. Research should extend beyond the discharge transition and examine the entire trajectory of posthospitalization care to better understand readmissions. Based directly on this study, research could investigate the practice patterns of ED providers and systems of care at ED facilities that affect readmissions rates. Such investigation could inform quality improvement efforts to standardize care for patients in the ED.

CMS policies hold hospitals accountable for readmissions of the patients they discharge, but do not address the admission process in the ED that leads to readmissions of recently discharged patients. Given the present study, and the fact that the proportion of all hospital admissions that occur through the ED has grown to 44%,[22] consideration of the role of the ED in public policy efforts to discourage unnecessary inpatient care may be appropriate.

In summary, this study shows that a recently discharged patient's chances of being readmitted depends partly on the ED provider who evaluates them and on the ED facility at which they seek care. ED provider practice patterns and ED facility systems of care may be a target for interventions aimed at decreasing readmission rates.

Hospital readmission, defined as an admission to a hospital within 30 days of discharge from an acute‐care hospitalization, is associated with short‐term morbidity, mortality, and medical costs.[1] In 2013, the Patient Protection and Affordable Care Act began assigning financial penalties to hospitals based on performance against benchmarks on readmission for acute myocardial infarction (AMI), pneumonia (PNA), and congestive heart failure (CHF) through its Hospital Readmission Reduction Program (HRRP).[2] In its third year, the program recently announced penalties for 2,610 hospitals that will total over $428 million.[3] Despite increased attention to this issue, few interventions have been identified that effectively reduce hospital readmissions.[4, 5]

Hospital discharge is a complex process that aims to achieve the safe transfer of care of a hospitalized patient to another setting (eg, home, skilled nursing facility [SNF]). Success depends on adequate staffing of physicians, nurses, case managers, social workers, and pharmacists; clear communication among patients and providers; and integrated coordination of care. Although much focus has been placed on the association between weekend hospital admission and increased mortality,[6, 7, 8] very little is known about the impact of weekend hospital discharge on outcomes, specifically hospital readmission rates. Furthermore, previous studies on this topic, based on Canadian data, have produced conflicting results.[9, 10, 11]

Staffing of physicians, physician extenders (eg, physician assistants or nurse practitioners), nurses, case managers, social workers, and ancillary staff (eg, physical and occupational therapists) are all typically reduced on the weekend. Patients may be cared for by covering healthcare providers. These factors may have important implications on the timeliness of discharge, accuracy of discharge instructions, safety of discharge (eg, clearance by physical therapy), and medication reconciliation, among others. Clinic offices are more likely to be closed, and therefore, some follow‐up appointments may inadvertently not be scheduled, and lack of timely postdischarge follow‐up may be associated with higher rates of readmission.[12] Reduced outpatient pharmacy availability may also cause delays in patients receiving their medications,[13] which may exacerbate failed transition to the outpatient setting due to medication noncompliance.[14]

Based on this rationale, the current study was designed to investigate the association between weekend discharge and 30‐ and 90‐ day readmissions in patients hospitalized for medical diagnoses included in Centers for Medicare and Medicaid Services' HRRP.[15] To do so, a large‐state, all‐payer discharge database with individual patient record linkage numbers (RLN) was selected to capture all readmissions, even those to a different hospital. We hypothesized that patients who are discharged on a weekend would have higher hospital readmission rates compared to those discharged on a weekday.

METHODS

Approval was obtained from both the California Committee for the Protection of Human Subjects and the Stanford University Institutional Review Board. The California Office of State Health Planning and Development (OSHPD) 2012 Patient Discharge Data (PDD) was utilized for this study. The OSHPD‐PDD contains records for all patients admitted and eventually discharged from every general, acute, nonfederal hospital within the state. Demographic variables contained in the dataset include age, gender, race, and a unique RLN (an individually assigned number based on the patient's social security number and other demographics) to associate discharged patients with subsequent hospitalizations. Clinical information collected included principal diagnosis (indication for admission), 24 additional diagnoses with an indicator as to whether or not the condition was present on admission (POA) to differentiate comorbidities from complications, and principle procedure codes. Details about the admission included date of admission and discharge, admission type (scheduled or unscheduled), expected payer/emnsurance and disposition (home, acute rehabilitation, skilled nursing facility, residential facility, other). Details about the hospital included a unique identification number to indicate the location of care for both index/discharge and subsequent readmission.

International Classification of Disease, Ninth Edition, Clinical Modification (ICD‐9‐CM) coding schema were used to identify all patients admitted with the principal diagnosis of AMI (ICD‐9‐CM code 410.xx), CHF (428.xx), or PNA (480.xx‐486.xx). We excluded patients who were coded as having in‐hospital mortality, as these patients would not be eligible for readmission, those who were transferred to a different inpatient acute‐care facility, and those with invalid RLNs. Patients were separated into 2 groups based on the day of discharge. Weekday was defined as Monday through Friday, whereas weekend was defined as Saturday and Sunday. The Charlson Comorbidity Index was calculated based on POA comorbidities.

Demographic data, hospital variables, and readmission rates were directly compared for patients discharged on a weekend compared to weekday after admission for AMI, CHF, or PNA. Hospital readmission was defined as the first inpatient hospitalization for any reason at either 30 or 90 days following discharge from an index acute‐care hospitalization. Hospital identification codes were used to determine whether the readmission occurred at the index (discharging) hospital or to a different facility. The principal diagnosis for the subsequent admission was assessed to identify the most common reasons for readmission.

The [2] test and Student t test were used to compare mean values between the 2 groups when appropriate, with statistical significance set as P<0.05. Univariate and multivariable logistic regression models were built to estimate the odds of hospital readmission based on weekend versus weekday discharge after controlling for age, gender, race, Charlson Comorbidity Index, discharge disposition, payer status, length of stay, presence of complication, and admission type. All statistical analyses were 2‐tailed and performed using SAS 9.3 for windows (SAS Institute Inc., Cary, NC). The odds ratio (OR) was considered significant when it was not equal to 1, the 95% confidence interval (CI) did not include 1, and the P value was less than 0.05.

RESULTS

Rate, Reason, and Location of Readmission

Table 2 shows overall rates of readmission. Among all patients, there were no significant differences in the unadjusted readmission rates for patients being discharged on a weekend versus weekday at either 30 days (16.7% vs 17.0%, P=0.14) or 90 days (26.9% vs 27.5%, P=0.05) (Table 2). Unadjusted 30‐day readmission rates were similar between the 2 groups for AMI (21.9% vs 21.9%, P=0.94) and PNA (12.1% vs 12.4%, P=0.28), whereas they were higher for weekday discharges in CHF (15.4% vs 16.0%, P=0.04). Similar results were seen for 90‐day readmission rates. To elucidate the impact of discharge disposition, a subset analysis was performed based on day of discharge and disposition (Figure 1). There was no difference in rates of readmission among patients discharged home on a weekend versus weekday (AMI: 21.3% vs 21.1%, P=0.78; CHF: 12.2% vs 12.6%, P=0.29; PNA: 8.3% vs 8.6%, P=0.29).

Figure 1

Table 2.Unadjusted Readmission Rates Based on Day of Discharge

	AMI			CHF			PNA
	Weekend	Weekday	P Value	Weekend	Weekday	P Value	Weekend	Weekday	P Value
NOTE: Abbreviations: AMI, acute myocardial infarction; CHF, congestive heart failure; PNA, pneumonia.
30‐day readmission (%)	3,954 (21.9)	13,106 (21.9)	0.94	3,162 (15.4)	11,366 (16.0)	0.04	2,608 (12.1)	9,380 (12.4)	0.28
90‐day readmission (%)	5,253 (29.1)	17,344 (29.0)	0.84	5,994 (29.3)	21,355 (30.2)	0.008	4,698 (21.8)	16,910 (22.3)	0.11

The reason for hospital readmission was most frequently related to the principal diagnosis. Among patients discharged after hospitalization for AMI, 45.3% of readmissions had a principal diagnosis of AMI, whereas 13.9% listed readmission for angina or coronary artery disease. Of CHF discharges, at least 26.7% of readmissions were for CHF. PNA was the principal diagnosis in 19.8% of readmissions after admission for PNA. A significant proportion of patients (AMI: 64.8%, CHF: 35.0%, PNA: 32.9%) were readmitted to a different hospital than the discharging hospital.

DISCUSSION

We used a California statewide discharge database that linked individual patient records from all nonfederal hospitals to examine 30‐ and 90‐day hospital readmissions for CHF, AMI, and PNA. We hypothesized, but did not find, that weekend hospital discharge would be associated with higher hospital readmission rates. We did find other factors that were associated with hospital readmissions, including race, age, greater comorbidities, male gender, and discharge to an SNF. Nearly half of patients were readmitted for the same diagnosis as the initial discharge diagnosis, and nearly two‐thirds of the patients were readmitted to a hospital different from the discharging hospital.

Our study found some findings similar to prior investigations. First, the factors that predicted hospital readmission were complex and included age, race, gender, comorbidities, payer status, length of hospital stay, and the occurrence of a complication; most of these factors persisted after multivariable analysis but were not necessarily consistent across all admission diagnoses.[16, 17, 18] One finding of particular interest was the impact of insurance status. Specifically, lack of insurance was inversely associated with hospital readmission; this finding warrants further investigation. Our study is also similar to others in that we found that the most common reasons for readmission are typically related to the reason for the principal admission. Dharmarajan et al. previously studied the reason for readmission among hospitalized Medicare patients with AMI, CHF, and PNA, and found similarly high rates of identical admission diagnoses.[19] Furthermore, in our study, between 32% and 65% of 30‐day readmissions were to a hospital different than the discharging facility. Although few prior studies have had the ability to assess readmission to alternative hospitals, those who have done so in the past have found similar rates of divergence from the index facility.[20, 21]

Despite the apparent similarities to other studies, the current research question was specifically designed to investigate the weekend effect of hospital discharge. The term weekend effect refers to a phenomenon of worse clinical outcomes (eg, morbidity,[22] mortality,[6, 7] intensive care unit [ICU] readmission,[23] delays in appropriate diagnostic imaging[24, 25] and intervention,[26, 27] LOS,[28] and hospital costs[29]) for care delivered on a weekend. In a landmark study, Bell and Redelmeier demonstrated increased in‐house mortality for patients with ruptured abdominal aortic aneurysm, pulmonary embolism, or acute epiglottitis admitted through the emergency department on a weekend compared to weekday.[6] After controlling for patient variables, the association persisted, suggesting system‐related factors were contributory. Similarly, Kostis et al. showed that patients admitted to the hospital on a weekend with AMI had higher 30‐day mortality rates compared to those with weekday admission.[7] Finally, Aylin et al. demonstrated that mortality was 44% higher for patients undergoing elective surgery on a Friday and 82% higher for surgery on a weekend compared to a Monday.[30]

Despite this robust literature, fewer studies have evaluated the relationship between timing of discharge and outcomes. Much of the initial research has been focused on timing of discharge from the ICU. For example, transfer out of the ICU at night has been associated with higher in‐hospital mortality[31, 32, 33, 34, 35] as well as ICU readmission.[36, 37] Discharge from the ICU on a weekend has been associated with increased mortality in some studies[23] but not in others.[35, 38] Van Walraven and Bell were the first to investigate the impact of weekend hospital discharge on outcomes. In their analysis of all discharges from Ontario hospitals between 1990 and 2000, patients discharged on a Friday were at increased risk of death and 30‐day readmission compared to discharge on a Wednesday.[9] Beck et al. performed a similar study in pediatric patients but did not find a statistically significant effect of Friday discharge on readmission rates.[39] McAlister et al. specifically studied the effect of weekend (Saturday or Sunday) discharge on patients with CHF by analyzing discharges from Alberta, Canada hospitals between 1999 and 2009. Despite being comprised of lower‐risk patients, weekend discharge was associated with greater rates of 30‐ and 90‐day death and hospital readmission.[10] Conversely, McAlister et al. evaluated general medicine discharges from teaching hospitals in Alberta, Canada between 2009 and 2011 and found no difference in hospital readmission rates among those discharged on a weekend versus weekday.[11] The current investigation is the first to study hospitals in the United States to address this topic, an important consideration given differences in American and Canadian healthcare systems. Nevertheless, our results are similar to those of McAlister et al.,[11] who found no difference in hospital readmission rates based on day of discharge among patients with AMI, CHF, or PNA.

One potential explanation for finding a lack of correlation between weekend discharge and readmissions is that patients at higher risk for readmission are already selected toward weekday discharge. Our study found that patients discharged to an SNF, a group with higher odds of readmission, were less often discharged on a weekend. There may be other unmeasurable factors that differ between patients discharged on weekends versus weekdays. Also, factors that bias healthcare providers' decision making on timing of discharge are difficult to quantify and may differ between the 2 groups. Although our study hypothesis was driven by the perception that weekend discharges may fare poorly because of inadequate resources on the weekend, an alternative explanation for finding no association may be that current systems in place already do an effective job of discharge coordination on the weekend. Despite fears that staffing and equipment are significantly reduced during the weekend, perhaps weekend discharge resources are not the limiting factor in efforts to reduce readmissions.

Our results challenge the idea that weekend discharges predict hospital readmissions in California and argue for the relative safety of weekend discharges. Based on these findings, the routine delay in discharge of the complex medical patient until Monday for fear of discharge on a weekend does not seem warranted. Avoiding unnecessary delays in discharge should have positive effects on healthcare costs by reducing LOS. Two additional implications of our work are that single institution studies may underestimate readmission rates,[40] and that discharge to an SNF should receive special consideration in calculation of hospital‐level penalties for subsequent readmissions, as this group is associated with particularly higher risk.

There are some limitations to our study that should be acknowledged. The use of administrative data has well known limitations and the possibility of coding inaccuracy cannot be excluded.[41] Certain factors that could potentially differ between groups, such as illness severity, as well as details on the discharge process, were not available in this administrative database. In addition, elective readmissions were not excluded from the study. Also, because of the way the data were coded, a significant percentage of discharge dispositions were unknown. Finally, although morbidity and mortality have been studied in previous reports,[9, 10, 39] these data were not available for the current study, limiting the applicability of its conclusions.

CONCLUSIONS

In conclusion, among patients admitted with AMI, CHF, or PNA in California, discharge on a weekend is not associated with hospital readmission. Future studies on hospital readmissions should use a population‐based approach to accurately capture all readmissions following discharge.

Hospital readmission, defined as an admission to a hospital within 30 days of discharge from an acute‐care hospitalization, is associated with short‐term morbidity, mortality, and medical costs.[1] In 2013, the Patient Protection and Affordable Care Act began assigning financial penalties to hospitals based on performance against benchmarks on readmission for acute myocardial infarction (AMI), pneumonia (PNA), and congestive heart failure (CHF) through its Hospital Readmission Reduction Program (HRRP).[2] In its third year, the program recently announced penalties for 2,610 hospitals that will total over $428 million.[3] Despite increased attention to this issue, few interventions have been identified that effectively reduce hospital readmissions.[4, 5]

Hospital discharge is a complex process that aims to achieve the safe transfer of care of a hospitalized patient to another setting (eg, home, skilled nursing facility [SNF]). Success depends on adequate staffing of physicians, nurses, case managers, social workers, and pharmacists; clear communication among patients and providers; and integrated coordination of care. Although much focus has been placed on the association between weekend hospital admission and increased mortality,[6, 7, 8] very little is known about the impact of weekend hospital discharge on outcomes, specifically hospital readmission rates. Furthermore, previous studies on this topic, based on Canadian data, have produced conflicting results.[9, 10, 11]

Staffing of physicians, physician extenders (eg, physician assistants or nurse practitioners), nurses, case managers, social workers, and ancillary staff (eg, physical and occupational therapists) are all typically reduced on the weekend. Patients may be cared for by covering healthcare providers. These factors may have important implications on the timeliness of discharge, accuracy of discharge instructions, safety of discharge (eg, clearance by physical therapy), and medication reconciliation, among others. Clinic offices are more likely to be closed, and therefore, some follow‐up appointments may inadvertently not be scheduled, and lack of timely postdischarge follow‐up may be associated with higher rates of readmission.[12] Reduced outpatient pharmacy availability may also cause delays in patients receiving their medications,[13] which may exacerbate failed transition to the outpatient setting due to medication noncompliance.[14]

Based on this rationale, the current study was designed to investigate the association between weekend discharge and 30‐ and 90‐ day readmissions in patients hospitalized for medical diagnoses included in Centers for Medicare and Medicaid Services' HRRP.[15] To do so, a large‐state, all‐payer discharge database with individual patient record linkage numbers (RLN) was selected to capture all readmissions, even those to a different hospital. We hypothesized that patients who are discharged on a weekend would have higher hospital readmission rates compared to those discharged on a weekday.

METHODS

Approval was obtained from both the California Committee for the Protection of Human Subjects and the Stanford University Institutional Review Board. The California Office of State Health Planning and Development (OSHPD) 2012 Patient Discharge Data (PDD) was utilized for this study. The OSHPD‐PDD contains records for all patients admitted and eventually discharged from every general, acute, nonfederal hospital within the state. Demographic variables contained in the dataset include age, gender, race, and a unique RLN (an individually assigned number based on the patient's social security number and other demographics) to associate discharged patients with subsequent hospitalizations. Clinical information collected included principal diagnosis (indication for admission), 24 additional diagnoses with an indicator as to whether or not the condition was present on admission (POA) to differentiate comorbidities from complications, and principle procedure codes. Details about the admission included date of admission and discharge, admission type (scheduled or unscheduled), expected payer/emnsurance and disposition (home, acute rehabilitation, skilled nursing facility, residential facility, other). Details about the hospital included a unique identification number to indicate the location of care for both index/discharge and subsequent readmission.

International Classification of Disease, Ninth Edition, Clinical Modification (ICD‐9‐CM) coding schema were used to identify all patients admitted with the principal diagnosis of AMI (ICD‐9‐CM code 410.xx), CHF (428.xx), or PNA (480.xx‐486.xx). We excluded patients who were coded as having in‐hospital mortality, as these patients would not be eligible for readmission, those who were transferred to a different inpatient acute‐care facility, and those with invalid RLNs. Patients were separated into 2 groups based on the day of discharge. Weekday was defined as Monday through Friday, whereas weekend was defined as Saturday and Sunday. The Charlson Comorbidity Index was calculated based on POA comorbidities.

Demographic data, hospital variables, and readmission rates were directly compared for patients discharged on a weekend compared to weekday after admission for AMI, CHF, or PNA. Hospital readmission was defined as the first inpatient hospitalization for any reason at either 30 or 90 days following discharge from an index acute‐care hospitalization. Hospital identification codes were used to determine whether the readmission occurred at the index (discharging) hospital or to a different facility. The principal diagnosis for the subsequent admission was assessed to identify the most common reasons for readmission.

The [2] test and Student t test were used to compare mean values between the 2 groups when appropriate, with statistical significance set as P<0.05. Univariate and multivariable logistic regression models were built to estimate the odds of hospital readmission based on weekend versus weekday discharge after controlling for age, gender, race, Charlson Comorbidity Index, discharge disposition, payer status, length of stay, presence of complication, and admission type. All statistical analyses were 2‐tailed and performed using SAS 9.3 for windows (SAS Institute Inc., Cary, NC). The odds ratio (OR) was considered significant when it was not equal to 1, the 95% confidence interval (CI) did not include 1, and the P value was less than 0.05.

RESULTS

Rate, Reason, and Location of Readmission

Table 2 shows overall rates of readmission. Among all patients, there were no significant differences in the unadjusted readmission rates for patients being discharged on a weekend versus weekday at either 30 days (16.7% vs 17.0%, P=0.14) or 90 days (26.9% vs 27.5%, P=0.05) (Table 2). Unadjusted 30‐day readmission rates were similar between the 2 groups for AMI (21.9% vs 21.9%, P=0.94) and PNA (12.1% vs 12.4%, P=0.28), whereas they were higher for weekday discharges in CHF (15.4% vs 16.0%, P=0.04). Similar results were seen for 90‐day readmission rates. To elucidate the impact of discharge disposition, a subset analysis was performed based on day of discharge and disposition (Figure 1). There was no difference in rates of readmission among patients discharged home on a weekend versus weekday (AMI: 21.3% vs 21.1%, P=0.78; CHF: 12.2% vs 12.6%, P=0.29; PNA: 8.3% vs 8.6%, P=0.29).

Figure 1

Table 2.Unadjusted Readmission Rates Based on Day of Discharge

	AMI			CHF			PNA
	Weekend	Weekday	P Value	Weekend	Weekday	P Value	Weekend	Weekday	P Value
NOTE: Abbreviations: AMI, acute myocardial infarction; CHF, congestive heart failure; PNA, pneumonia.
30‐day readmission (%)	3,954 (21.9)	13,106 (21.9)	0.94	3,162 (15.4)	11,366 (16.0)	0.04	2,608 (12.1)	9,380 (12.4)	0.28
90‐day readmission (%)	5,253 (29.1)	17,344 (29.0)	0.84	5,994 (29.3)	21,355 (30.2)	0.008	4,698 (21.8)	16,910 (22.3)	0.11

The reason for hospital readmission was most frequently related to the principal diagnosis. Among patients discharged after hospitalization for AMI, 45.3% of readmissions had a principal diagnosis of AMI, whereas 13.9% listed readmission for angina or coronary artery disease. Of CHF discharges, at least 26.7% of readmissions were for CHF. PNA was the principal diagnosis in 19.8% of readmissions after admission for PNA. A significant proportion of patients (AMI: 64.8%, CHF: 35.0%, PNA: 32.9%) were readmitted to a different hospital than the discharging hospital.

DISCUSSION

We used a California statewide discharge database that linked individual patient records from all nonfederal hospitals to examine 30‐ and 90‐day hospital readmissions for CHF, AMI, and PNA. We hypothesized, but did not find, that weekend hospital discharge would be associated with higher hospital readmission rates. We did find other factors that were associated with hospital readmissions, including race, age, greater comorbidities, male gender, and discharge to an SNF. Nearly half of patients were readmitted for the same diagnosis as the initial discharge diagnosis, and nearly two‐thirds of the patients were readmitted to a hospital different from the discharging hospital.

Our study found some findings similar to prior investigations. First, the factors that predicted hospital readmission were complex and included age, race, gender, comorbidities, payer status, length of hospital stay, and the occurrence of a complication; most of these factors persisted after multivariable analysis but were not necessarily consistent across all admission diagnoses.[16, 17, 18] One finding of particular interest was the impact of insurance status. Specifically, lack of insurance was inversely associated with hospital readmission; this finding warrants further investigation. Our study is also similar to others in that we found that the most common reasons for readmission are typically related to the reason for the principal admission. Dharmarajan et al. previously studied the reason for readmission among hospitalized Medicare patients with AMI, CHF, and PNA, and found similarly high rates of identical admission diagnoses.[19] Furthermore, in our study, between 32% and 65% of 30‐day readmissions were to a hospital different than the discharging facility. Although few prior studies have had the ability to assess readmission to alternative hospitals, those who have done so in the past have found similar rates of divergence from the index facility.[20, 21]

Despite the apparent similarities to other studies, the current research question was specifically designed to investigate the weekend effect of hospital discharge. The term weekend effect refers to a phenomenon of worse clinical outcomes (eg, morbidity,[22] mortality,[6, 7] intensive care unit [ICU] readmission,[23] delays in appropriate diagnostic imaging[24, 25] and intervention,[26, 27] LOS,[28] and hospital costs[29]) for care delivered on a weekend. In a landmark study, Bell and Redelmeier demonstrated increased in‐house mortality for patients with ruptured abdominal aortic aneurysm, pulmonary embolism, or acute epiglottitis admitted through the emergency department on a weekend compared to weekday.[6] After controlling for patient variables, the association persisted, suggesting system‐related factors were contributory. Similarly, Kostis et al. showed that patients admitted to the hospital on a weekend with AMI had higher 30‐day mortality rates compared to those with weekday admission.[7] Finally, Aylin et al. demonstrated that mortality was 44% higher for patients undergoing elective surgery on a Friday and 82% higher for surgery on a weekend compared to a Monday.[30]

Despite this robust literature, fewer studies have evaluated the relationship between timing of discharge and outcomes. Much of the initial research has been focused on timing of discharge from the ICU. For example, transfer out of the ICU at night has been associated with higher in‐hospital mortality[31, 32, 33, 34, 35] as well as ICU readmission.[36, 37] Discharge from the ICU on a weekend has been associated with increased mortality in some studies[23] but not in others.[35, 38] Van Walraven and Bell were the first to investigate the impact of weekend hospital discharge on outcomes. In their analysis of all discharges from Ontario hospitals between 1990 and 2000, patients discharged on a Friday were at increased risk of death and 30‐day readmission compared to discharge on a Wednesday.[9] Beck et al. performed a similar study in pediatric patients but did not find a statistically significant effect of Friday discharge on readmission rates.[39] McAlister et al. specifically studied the effect of weekend (Saturday or Sunday) discharge on patients with CHF by analyzing discharges from Alberta, Canada hospitals between 1999 and 2009. Despite being comprised of lower‐risk patients, weekend discharge was associated with greater rates of 30‐ and 90‐day death and hospital readmission.[10] Conversely, McAlister et al. evaluated general medicine discharges from teaching hospitals in Alberta, Canada between 2009 and 2011 and found no difference in hospital readmission rates among those discharged on a weekend versus weekday.[11] The current investigation is the first to study hospitals in the United States to address this topic, an important consideration given differences in American and Canadian healthcare systems. Nevertheless, our results are similar to those of McAlister et al.,[11] who found no difference in hospital readmission rates based on day of discharge among patients with AMI, CHF, or PNA.

One potential explanation for finding a lack of correlation between weekend discharge and readmissions is that patients at higher risk for readmission are already selected toward weekday discharge. Our study found that patients discharged to an SNF, a group with higher odds of readmission, were less often discharged on a weekend. There may be other unmeasurable factors that differ between patients discharged on weekends versus weekdays. Also, factors that bias healthcare providers' decision making on timing of discharge are difficult to quantify and may differ between the 2 groups. Although our study hypothesis was driven by the perception that weekend discharges may fare poorly because of inadequate resources on the weekend, an alternative explanation for finding no association may be that current systems in place already do an effective job of discharge coordination on the weekend. Despite fears that staffing and equipment are significantly reduced during the weekend, perhaps weekend discharge resources are not the limiting factor in efforts to reduce readmissions.

Our results challenge the idea that weekend discharges predict hospital readmissions in California and argue for the relative safety of weekend discharges. Based on these findings, the routine delay in discharge of the complex medical patient until Monday for fear of discharge on a weekend does not seem warranted. Avoiding unnecessary delays in discharge should have positive effects on healthcare costs by reducing LOS. Two additional implications of our work are that single institution studies may underestimate readmission rates,[40] and that discharge to an SNF should receive special consideration in calculation of hospital‐level penalties for subsequent readmissions, as this group is associated with particularly higher risk.

There are some limitations to our study that should be acknowledged. The use of administrative data has well known limitations and the possibility of coding inaccuracy cannot be excluded.[41] Certain factors that could potentially differ between groups, such as illness severity, as well as details on the discharge process, were not available in this administrative database. In addition, elective readmissions were not excluded from the study. Also, because of the way the data were coded, a significant percentage of discharge dispositions were unknown. Finally, although morbidity and mortality have been studied in previous reports,[9, 10, 39] these data were not available for the current study, limiting the applicability of its conclusions.

CONCLUSIONS

In conclusion, among patients admitted with AMI, CHF, or PNA in California, discharge on a weekend is not associated with hospital readmission. Future studies on hospital readmissions should use a population‐based approach to accurately capture all readmissions following discharge.

Hospital readmission, defined as an admission to a hospital within 30 days of discharge from an acute‐care hospitalization, is associated with short‐term morbidity, mortality, and medical costs.[1] In 2013, the Patient Protection and Affordable Care Act began assigning financial penalties to hospitals based on performance against benchmarks on readmission for acute myocardial infarction (AMI), pneumonia (PNA), and congestive heart failure (CHF) through its Hospital Readmission Reduction Program (HRRP).[2] In its third year, the program recently announced penalties for 2,610 hospitals that will total over $428 million.[3] Despite increased attention to this issue, few interventions have been identified that effectively reduce hospital readmissions.[4, 5]

Hospital discharge is a complex process that aims to achieve the safe transfer of care of a hospitalized patient to another setting (eg, home, skilled nursing facility [SNF]). Success depends on adequate staffing of physicians, nurses, case managers, social workers, and pharmacists; clear communication among patients and providers; and integrated coordination of care. Although much focus has been placed on the association between weekend hospital admission and increased mortality,[6, 7, 8] very little is known about the impact of weekend hospital discharge on outcomes, specifically hospital readmission rates. Furthermore, previous studies on this topic, based on Canadian data, have produced conflicting results.[9, 10, 11]

Staffing of physicians, physician extenders (eg, physician assistants or nurse practitioners), nurses, case managers, social workers, and ancillary staff (eg, physical and occupational therapists) are all typically reduced on the weekend. Patients may be cared for by covering healthcare providers. These factors may have important implications on the timeliness of discharge, accuracy of discharge instructions, safety of discharge (eg, clearance by physical therapy), and medication reconciliation, among others. Clinic offices are more likely to be closed, and therefore, some follow‐up appointments may inadvertently not be scheduled, and lack of timely postdischarge follow‐up may be associated with higher rates of readmission.[12] Reduced outpatient pharmacy availability may also cause delays in patients receiving their medications,[13] which may exacerbate failed transition to the outpatient setting due to medication noncompliance.[14]

Based on this rationale, the current study was designed to investigate the association between weekend discharge and 30‐ and 90‐ day readmissions in patients hospitalized for medical diagnoses included in Centers for Medicare and Medicaid Services' HRRP.[15] To do so, a large‐state, all‐payer discharge database with individual patient record linkage numbers (RLN) was selected to capture all readmissions, even those to a different hospital. We hypothesized that patients who are discharged on a weekend would have higher hospital readmission rates compared to those discharged on a weekday.

METHODS

Approval was obtained from both the California Committee for the Protection of Human Subjects and the Stanford University Institutional Review Board. The California Office of State Health Planning and Development (OSHPD) 2012 Patient Discharge Data (PDD) was utilized for this study. The OSHPD‐PDD contains records for all patients admitted and eventually discharged from every general, acute, nonfederal hospital within the state. Demographic variables contained in the dataset include age, gender, race, and a unique RLN (an individually assigned number based on the patient's social security number and other demographics) to associate discharged patients with subsequent hospitalizations. Clinical information collected included principal diagnosis (indication for admission), 24 additional diagnoses with an indicator as to whether or not the condition was present on admission (POA) to differentiate comorbidities from complications, and principle procedure codes. Details about the admission included date of admission and discharge, admission type (scheduled or unscheduled), expected payer/emnsurance and disposition (home, acute rehabilitation, skilled nursing facility, residential facility, other). Details about the hospital included a unique identification number to indicate the location of care for both index/discharge and subsequent readmission.

International Classification of Disease, Ninth Edition, Clinical Modification (ICD‐9‐CM) coding schema were used to identify all patients admitted with the principal diagnosis of AMI (ICD‐9‐CM code 410.xx), CHF (428.xx), or PNA (480.xx‐486.xx). We excluded patients who were coded as having in‐hospital mortality, as these patients would not be eligible for readmission, those who were transferred to a different inpatient acute‐care facility, and those with invalid RLNs. Patients were separated into 2 groups based on the day of discharge. Weekday was defined as Monday through Friday, whereas weekend was defined as Saturday and Sunday. The Charlson Comorbidity Index was calculated based on POA comorbidities.

Demographic data, hospital variables, and readmission rates were directly compared for patients discharged on a weekend compared to weekday after admission for AMI, CHF, or PNA. Hospital readmission was defined as the first inpatient hospitalization for any reason at either 30 or 90 days following discharge from an index acute‐care hospitalization. Hospital identification codes were used to determine whether the readmission occurred at the index (discharging) hospital or to a different facility. The principal diagnosis for the subsequent admission was assessed to identify the most common reasons for readmission.

The [2] test and Student t test were used to compare mean values between the 2 groups when appropriate, with statistical significance set as P<0.05. Univariate and multivariable logistic regression models were built to estimate the odds of hospital readmission based on weekend versus weekday discharge after controlling for age, gender, race, Charlson Comorbidity Index, discharge disposition, payer status, length of stay, presence of complication, and admission type. All statistical analyses were 2‐tailed and performed using SAS 9.3 for windows (SAS Institute Inc., Cary, NC). The odds ratio (OR) was considered significant when it was not equal to 1, the 95% confidence interval (CI) did not include 1, and the P value was less than 0.05.

RESULTS

Rate, Reason, and Location of Readmission

Table 2 shows overall rates of readmission. Among all patients, there were no significant differences in the unadjusted readmission rates for patients being discharged on a weekend versus weekday at either 30 days (16.7% vs 17.0%, P=0.14) or 90 days (26.9% vs 27.5%, P=0.05) (Table 2). Unadjusted 30‐day readmission rates were similar between the 2 groups for AMI (21.9% vs 21.9%, P=0.94) and PNA (12.1% vs 12.4%, P=0.28), whereas they were higher for weekday discharges in CHF (15.4% vs 16.0%, P=0.04). Similar results were seen for 90‐day readmission rates. To elucidate the impact of discharge disposition, a subset analysis was performed based on day of discharge and disposition (Figure 1). There was no difference in rates of readmission among patients discharged home on a weekend versus weekday (AMI: 21.3% vs 21.1%, P=0.78; CHF: 12.2% vs 12.6%, P=0.29; PNA: 8.3% vs 8.6%, P=0.29).

Figure 1

Table 2.Unadjusted Readmission Rates Based on Day of Discharge

	AMI			CHF			PNA
	Weekend	Weekday	P Value	Weekend	Weekday	P Value	Weekend	Weekday	P Value
NOTE: Abbreviations: AMI, acute myocardial infarction; CHF, congestive heart failure; PNA, pneumonia.
30‐day readmission (%)	3,954 (21.9)	13,106 (21.9)	0.94	3,162 (15.4)	11,366 (16.0)	0.04	2,608 (12.1)	9,380 (12.4)	0.28
90‐day readmission (%)	5,253 (29.1)	17,344 (29.0)	0.84	5,994 (29.3)	21,355 (30.2)	0.008	4,698 (21.8)	16,910 (22.3)	0.11

The reason for hospital readmission was most frequently related to the principal diagnosis. Among patients discharged after hospitalization for AMI, 45.3% of readmissions had a principal diagnosis of AMI, whereas 13.9% listed readmission for angina or coronary artery disease. Of CHF discharges, at least 26.7% of readmissions were for CHF. PNA was the principal diagnosis in 19.8% of readmissions after admission for PNA. A significant proportion of patients (AMI: 64.8%, CHF: 35.0%, PNA: 32.9%) were readmitted to a different hospital than the discharging hospital.

DISCUSSION

We used a California statewide discharge database that linked individual patient records from all nonfederal hospitals to examine 30‐ and 90‐day hospital readmissions for CHF, AMI, and PNA. We hypothesized, but did not find, that weekend hospital discharge would be associated with higher hospital readmission rates. We did find other factors that were associated with hospital readmissions, including race, age, greater comorbidities, male gender, and discharge to an SNF. Nearly half of patients were readmitted for the same diagnosis as the initial discharge diagnosis, and nearly two‐thirds of the patients were readmitted to a hospital different from the discharging hospital.

Our study found some findings similar to prior investigations. First, the factors that predicted hospital readmission were complex and included age, race, gender, comorbidities, payer status, length of hospital stay, and the occurrence of a complication; most of these factors persisted after multivariable analysis but were not necessarily consistent across all admission diagnoses.[16, 17, 18] One finding of particular interest was the impact of insurance status. Specifically, lack of insurance was inversely associated with hospital readmission; this finding warrants further investigation. Our study is also similar to others in that we found that the most common reasons for readmission are typically related to the reason for the principal admission. Dharmarajan et al. previously studied the reason for readmission among hospitalized Medicare patients with AMI, CHF, and PNA, and found similarly high rates of identical admission diagnoses.[19] Furthermore, in our study, between 32% and 65% of 30‐day readmissions were to a hospital different than the discharging facility. Although few prior studies have had the ability to assess readmission to alternative hospitals, those who have done so in the past have found similar rates of divergence from the index facility.[20, 21]

Despite the apparent similarities to other studies, the current research question was specifically designed to investigate the weekend effect of hospital discharge. The term weekend effect refers to a phenomenon of worse clinical outcomes (eg, morbidity,[22] mortality,[6, 7] intensive care unit [ICU] readmission,[23] delays in appropriate diagnostic imaging[24, 25] and intervention,[26, 27] LOS,[28] and hospital costs[29]) for care delivered on a weekend. In a landmark study, Bell and Redelmeier demonstrated increased in‐house mortality for patients with ruptured abdominal aortic aneurysm, pulmonary embolism, or acute epiglottitis admitted through the emergency department on a weekend compared to weekday.[6] After controlling for patient variables, the association persisted, suggesting system‐related factors were contributory. Similarly, Kostis et al. showed that patients admitted to the hospital on a weekend with AMI had higher 30‐day mortality rates compared to those with weekday admission.[7] Finally, Aylin et al. demonstrated that mortality was 44% higher for patients undergoing elective surgery on a Friday and 82% higher for surgery on a weekend compared to a Monday.[30]

Despite this robust literature, fewer studies have evaluated the relationship between timing of discharge and outcomes. Much of the initial research has been focused on timing of discharge from the ICU. For example, transfer out of the ICU at night has been associated with higher in‐hospital mortality[31, 32, 33, 34, 35] as well as ICU readmission.[36, 37] Discharge from the ICU on a weekend has been associated with increased mortality in some studies[23] but not in others.[35, 38] Van Walraven and Bell were the first to investigate the impact of weekend hospital discharge on outcomes. In their analysis of all discharges from Ontario hospitals between 1990 and 2000, patients discharged on a Friday were at increased risk of death and 30‐day readmission compared to discharge on a Wednesday.[9] Beck et al. performed a similar study in pediatric patients but did not find a statistically significant effect of Friday discharge on readmission rates.[39] McAlister et al. specifically studied the effect of weekend (Saturday or Sunday) discharge on patients with CHF by analyzing discharges from Alberta, Canada hospitals between 1999 and 2009. Despite being comprised of lower‐risk patients, weekend discharge was associated with greater rates of 30‐ and 90‐day death and hospital readmission.[10] Conversely, McAlister et al. evaluated general medicine discharges from teaching hospitals in Alberta, Canada between 2009 and 2011 and found no difference in hospital readmission rates among those discharged on a weekend versus weekday.[11] The current investigation is the first to study hospitals in the United States to address this topic, an important consideration given differences in American and Canadian healthcare systems. Nevertheless, our results are similar to those of McAlister et al.,[11] who found no difference in hospital readmission rates based on day of discharge among patients with AMI, CHF, or PNA.

One potential explanation for finding a lack of correlation between weekend discharge and readmissions is that patients at higher risk for readmission are already selected toward weekday discharge. Our study found that patients discharged to an SNF, a group with higher odds of readmission, were less often discharged on a weekend. There may be other unmeasurable factors that differ between patients discharged on weekends versus weekdays. Also, factors that bias healthcare providers' decision making on timing of discharge are difficult to quantify and may differ between the 2 groups. Although our study hypothesis was driven by the perception that weekend discharges may fare poorly because of inadequate resources on the weekend, an alternative explanation for finding no association may be that current systems in place already do an effective job of discharge coordination on the weekend. Despite fears that staffing and equipment are significantly reduced during the weekend, perhaps weekend discharge resources are not the limiting factor in efforts to reduce readmissions.

Our results challenge the idea that weekend discharges predict hospital readmissions in California and argue for the relative safety of weekend discharges. Based on these findings, the routine delay in discharge of the complex medical patient until Monday for fear of discharge on a weekend does not seem warranted. Avoiding unnecessary delays in discharge should have positive effects on healthcare costs by reducing LOS. Two additional implications of our work are that single institution studies may underestimate readmission rates,[40] and that discharge to an SNF should receive special consideration in calculation of hospital‐level penalties for subsequent readmissions, as this group is associated with particularly higher risk.

There are some limitations to our study that should be acknowledged. The use of administrative data has well known limitations and the possibility of coding inaccuracy cannot be excluded.[41] Certain factors that could potentially differ between groups, such as illness severity, as well as details on the discharge process, were not available in this administrative database. In addition, elective readmissions were not excluded from the study. Also, because of the way the data were coded, a significant percentage of discharge dispositions were unknown. Finally, although morbidity and mortality have been studied in previous reports,[9, 10, 39] these data were not available for the current study, limiting the applicability of its conclusions.

CONCLUSIONS

In conclusion, among patients admitted with AMI, CHF, or PNA in California, discharge on a weekend is not associated with hospital readmission. Future studies on hospital readmissions should use a population‐based approach to accurately capture all readmissions following discharge.