Scott A. Lorch, MD, MSCE

Disparities in patterns of care and outcomes for ambulatory‐care sensitive conditions remain a persistent problem for children.19 Many studies have focused on disparities in hospitalization rates and length of stay (LOS) related to asthma, however, few studies have focused on community‐acquired pneumonia (CAP) despite the fact that pneumonia is the most common, preventable, and potentially serious infection in childhood.10 Providers, payers, and families have a common interest in minimizing hospital LOS for different reasons (eg, minimizing costs, lost wages, exposure to antibiotic‐resistant bacteria), however, this interest is balanced against the potentially greater risk of readmission and adverse outcomes if LOS is inappropriately short. To date, the relationship between insurance status and LOS for CAP remains unexplored.

As in other conditions, substantial variation exists with respect to patterns of care and outcomes for children hospitalized with CAP.11 For example, children hospitalized in rural settings have a shorter LOS for pneumonia than those hospitalized in large urban settings.12 Children from racial/ethnic minorities tend to have higher rates of CAP‐associated complications, including death.11 Decades of prior studies have documented that uninsured children are less likely than insured children to make preventive care visits and obtain prescription medications, but differences in LOS or hospitalization rates between insured and uninsured children with CAP have not been studied.6, 8, 13, 14 Though imperfect, insurance status is 1 proxy for healthcare access, and current healthcare reform efforts aim to improve healthcare access and decrease socioeconomic gradients in health by increasing the number of insured American children. Nonetheless, quantifying the relationship between insurance status on LOS for children hospitalized with CAP is a first step towards understanding the influence of ambulatory care access on hospitalization for ambulatory‐care sensitive conditions.

The purpose of this study was to investigate the influence of insurance status and type on LOS for children hospitalized with CAP. In addition, we sought to determine if there were consistent trends over time in the association between insurance status and type with LOS for children hospitalized with CAP.

METHODS

RESULTS

The more than 10.5 million children sampled (unweighted) in KID during these 4 time periods (1997, 2000, 2003, and 2006) are representative of the more than 28.9 million children hospitalized in the United States. In each of these sample years, there were approximately 150,000 children hospitalized with pneumonia across the United States (Table 1). Of those hospitalized, 23% to 28% had a concomitant diagnosis of asthma; 6% to 8% had a pneumonia‐associated complication; and mortality was <0.01% in each sample year for patients hospitalized with pneumonia. In all years, among those with racial/ethnic data, the sample population was predominantly white boys less than 6 years old. The greatest proportion of children were hospitalized in urban non‐teaching settings, and also those children living in the southern regions of the United States.

There was little variation in the insurance status of children hospitalized with CAP between 1997 and 2006. In each of the sampled years, at least 40% of sampled children were privately insured, at least 40% were publicly insured, and approximately 5% were uninsured (Table 1). In all years, there were significant racial/ethnic disparities in insurance coverage such that whites were 4 to 6 times more likely to have private insurance than blacks, however, the large amount of missing race/ethnicity data warrant caution in interpreting this finding (Table 2; also see Supporting Information Appendix B in the online version of this article). We also found that children less than 1 year old were the most likely to be publicly insured in all years (see Supporting Appendix C in the online version of this article). There were also regional differences related to insurance coverage such that a greater proportion of children hospitalized in facilities located in the southern part of the United States were publicly insured. Notably, there were no significant differences in CAP‐associated mortality or asthma related to insurance coverage (Table 2). In 2006, CAP‐associated complications occurred in 8.5% of children with private insurance, 6.5% of children with public insurance, and 7.7% of uninsured children; the relative distribution of complications by insurance type were similar in previous years of the KID survey.

After examining the general and demographic characteristics, we then examined mean LOS for all children with CAP in each sample year (Table 3). The mean LOS for children with CAP was 3.44 days in 1997, with marginal decreases in subsequent years to a mean LOS of 3.18 days in 2006. The distribution of LOS for children with CAP revealed that nearly 70% of children were hospitalized for fewer than 3 days, another 22% to 28% were hospitalized for less than 1 week, and only 3% were hospitalized for more than 1 week. This distribution did not change substantially between 1997 and 2006. Next, we compared mean LOS by insurance type and race/ethnicity in unadjusted analyses. In each sample year, publicly insured children hospitalized with CAP had significantly longer LOS than privately insured children (P < 0.001). Similarly, in all years excepting 1997, uninsured children hospitalized with CAP had significantly shorter LOS than privately insured children. There were also significant racial differences in LOS for children with CAP, such that black children had longer LOS than white children with CAP. However, the large amount of missing data for race/ethnicity limited the robustness of this finding, and subsequent sensitivity analyses demonstrated that there were no consistent racial/ethnic disparities in LOS (see Supporting Appendix B in the online version of this article). These sensitivity analyses for missing race data did not alter our primary finding of shorter LOS for uninsured versus publicly or privately insured children.

After controlling for child age, race/ethnicity, gender, hospital type, transfer status, and presence of asthma or pneumonia‐associated complications, our multivariable analyses examining the relationship between insurance coverage and hospital LOS yielded the following results (Table 4). First, publicly insured children had significantly longer hospital stays than privately insured children, and uninsured children had significantly shorter hospital stays than privately insured children in all years except 1997. Second, children admitted with CAP at urban teaching children's hospitals had significantly longer LOS than those admitted to urban non‐teaching hospitals, and, in 2003, children admitted with CAP to rural hospitals had significantly shorter LOS than those admitted to urban non‐teaching hospitals. Third, children older than 1 year consistently had shorter hospital stays than infants less than 1 year old. Finally, though concomitant diagnosis of asthma did not consistently influence LOS, children who developed any complications had significantly longer LOS than those who did not. The cumulative impact of seemingly small differences in LOS is great. For example, in 2006, our model suggests that, for every 1000 children hospitalized with CAP in a given year, after adjusting for differences in sex, age, race, hospital‐type, region, transfer status, and diagnosis of asthma or complications, publicly insured children spend 90 to 130 more days in the hospital than privately insured children, whereas uninsured children spend between 40 to 90 fewer days in the hospital than privately insured children.

DISCUSSION

In this nationally representative sample selected over the past 10 years, we found that publicly insured children hospitalized with CAP have significantly longer LOS than those who are privately insured, and that, since 2000, uninsured children hospitalized with CAP have significantly shorter LOS than those who are privately insured. Though these observed differences are small, they are consistent across all 4 sampled years and, because CAP is one of the most common pediatric inpatient diagnoses, the cumulative impact of the observed differences on hospital LOS is great. Insurance status is often considered a proxy for access to preventive and ambulatory healthcare services or socioeconomic status. However, the underlying mechanisms relating insurance status to healthcare access, utilization, and ultimately, health outcomes are highly complex and difficult to elucidate.17 The observed variation in this study raises questions about the potential influence of insurance status on hospital discharge practices. Additional research is necessary to understand whether there are differences in processes of care (eg, performance of blood cultures or chest radiographs), quality of care, or other outcomes, such as readmissions, related to CAP inpatient management for children with different insurance coverage.

Apart from differences in hospital discharge practices, another possible explanation for uninsured children with CAP having shorter LOS is that these children have less severe disease than privately insured. This may occur if uninsured children with CAP are evaluated in the emergency department rather than the office setting, because emergency department providers may be more likely to admit children with CAP who lack a consistent access to ambulatory primary care services. Countering this alternative, prior studies have shown that uninsured groups are more likely to have greater disease severity than privately insured groups at the time of hospital admission.18, 19 In this study, we attempted to identify children with greater severity of disease using ICD‐9 codes for CAP‐associated complications. Though this is a relatively crude method that might lead to an underestimate of the total number of children with complications, we found that there were no significant differences in the prevalence of CAP‐associated complications between uninsured and insured groups in all sampled years.

On the other hand, uninsured patients may be released earlier by providers in order to reduce the amount of uncompensated care provided, or possibly because parents may urge providers to discharge their children, given their inability to pay forthcoming hospital bills and/or avoid further lost wages due to work absence.20, 21 In California, Bindman et al. demonstrated that decreasing the frequency of Medicaid recertification, and consequently increasing the likelihood of continuous insurance coverage, was associated with a decreased risk of hospitalization for ambulatory‐care sensitive conditions.5

We also found that children admitted to urban teaching children's hospitals with CAP had significantly longer LOS than those admitted to urban non‐teaching hospitals, whereas children in rural hospitals had significantly shorter LOS than those in urban non‐teaching hospitals in 2003. These findings are consistent with prior data from 1996 to1998 demonstrating that children admitted to rural hospitals in New York and Pennsylvania had significantly shorter LOS than large urban hospitals for 19 medical and 9 surgical conditions, including pneumonia.12 These findings may reflect underlying differences in between rural and urban hospital transfer practices, whereby rural hospitals may be more likely than urban hospitals to transfer children with relatively more severe illness to urban referral centers and retain children with less severe illness, leading to shorter LOS.12 Though our empiric understanding of differences in LOS between teaching and non‐teaching hospitals is currently limited, clinical experience supports the notion that there may be decreases in efficiency that occur in teaching hospitals, and are a result of the supervision required for care provided by trainees. It is also possible that, despite our exclusion of comorbid conditions, some children with complex or chronic medical conditions were included in this study. These children are often cared for at teaching hospitals, regardless of the primary cause for admission, and are more likely to have public insurance than other children, thus confounding the relationship between hospital type, insurance type and status, and LOS for children with CAP. The limitations of this dataset preclude further examination of this issue.

There are some limitations to this study. First, the KID data are cross‐sectional and causal inferences are limited. However, our results demonstrating that uninsured children hospitalized with CAP had shorter LOS than privately insured children were quite consistent in each sample year, suggesting that our results are a true association. Additionally, insurance status in KID is typically collected at admission, however, it is not possible to determine whether specific changes to insurance status that occurred during the hospitalization were applied to the data. The impact of this limitation would depend on the type of insurance obtained by the patient. If uninsured patients obtained public insurance, our study would underestimate the increased LOS for publicly insured patients, compared with privately insured patients, but have no effect on the difference in LOS between uninsured and privately insured patients. In the unlikely event that uninsured patients obtained private insurance, then our study would underestimate the difference for uninsured patients, compared with privately insured patients, biasing our current study results towards the null. Second, a substantial proportion of sampled children had missing data for race/ethnicity. To assess the impact of the missing race/ethnicity data on our results, we conducted sensitivity analyses and found that, though difficult to make any definitive conclusions about the relationship between race/ethnicity and LOS for children with CAP, there were no changes to our primary findings regarding differences in LOS between children with different insurance status and type. Third, KID does not include data about other unmeasured confounders (eg, parent income, parent education, regular source of care) that might be related to LOS, as well as a broad spectrum of pediatric outcomes. Serious consideration of expanding KID to include these variables is warranted. Fourth, the other category of insurance is not uniformly coded across states in the KID database. While some states use this category to classify public insurance options other than Medicare and Medicaid, other states include private insurance options in this group. Thus, it is possible that some patients with public insurance are misclassified as having other insurance. We would expect such misclassification to bias our findings towards the null hypothesis. Finally, we focused on the relationship between child health insurance status and CAP, only 1 ambulatory care‐sensitive condition. Additional research examining the relationship between insurance type and other ambulatory care‐sensitive conditions is warranted.

In summary, we found that, after multivariable adjustment, uninsured children hospitalized with community‐acquired pneumonia had significantly shorter LOS than privately insured children, and publicly insured children had a significantly longer hospital stay than privately insured children in these 4 nationally representative samples from 1997 to 2006. Current federal and state efforts to increase enrollment of children into insurance programs are a first step in reducing healthcare disparities. However, insurance coverage alone does not guarantee access to healthcare, thus, these efforts in isolation will likely be insufficient to achieve optimal health for the children of our country. As healthcare reform legislation is implemented, these findings provide hospitals and policy makers additional impetus to develop ways to achieve the ideal length of stay for every child; this ideal state will be achieved when clinical status and course, rather than nonclinical factors such as insurance type or provider's unease with ambulatory follow‐up, determine the duration of hospitalization for every child.

Disparities in patterns of care and outcomes for ambulatory‐care sensitive conditions remain a persistent problem for children.19 Many studies have focused on disparities in hospitalization rates and length of stay (LOS) related to asthma, however, few studies have focused on community‐acquired pneumonia (CAP) despite the fact that pneumonia is the most common, preventable, and potentially serious infection in childhood.10 Providers, payers, and families have a common interest in minimizing hospital LOS for different reasons (eg, minimizing costs, lost wages, exposure to antibiotic‐resistant bacteria), however, this interest is balanced against the potentially greater risk of readmission and adverse outcomes if LOS is inappropriately short. To date, the relationship between insurance status and LOS for CAP remains unexplored.

As in other conditions, substantial variation exists with respect to patterns of care and outcomes for children hospitalized with CAP.11 For example, children hospitalized in rural settings have a shorter LOS for pneumonia than those hospitalized in large urban settings.12 Children from racial/ethnic minorities tend to have higher rates of CAP‐associated complications, including death.11 Decades of prior studies have documented that uninsured children are less likely than insured children to make preventive care visits and obtain prescription medications, but differences in LOS or hospitalization rates between insured and uninsured children with CAP have not been studied.6, 8, 13, 14 Though imperfect, insurance status is 1 proxy for healthcare access, and current healthcare reform efforts aim to improve healthcare access and decrease socioeconomic gradients in health by increasing the number of insured American children. Nonetheless, quantifying the relationship between insurance status on LOS for children hospitalized with CAP is a first step towards understanding the influence of ambulatory care access on hospitalization for ambulatory‐care sensitive conditions.

The purpose of this study was to investigate the influence of insurance status and type on LOS for children hospitalized with CAP. In addition, we sought to determine if there were consistent trends over time in the association between insurance status and type with LOS for children hospitalized with CAP.

METHODS

RESULTS

The more than 10.5 million children sampled (unweighted) in KID during these 4 time periods (1997, 2000, 2003, and 2006) are representative of the more than 28.9 million children hospitalized in the United States. In each of these sample years, there were approximately 150,000 children hospitalized with pneumonia across the United States (Table 1). Of those hospitalized, 23% to 28% had a concomitant diagnosis of asthma; 6% to 8% had a pneumonia‐associated complication; and mortality was <0.01% in each sample year for patients hospitalized with pneumonia. In all years, among those with racial/ethnic data, the sample population was predominantly white boys less than 6 years old. The greatest proportion of children were hospitalized in urban non‐teaching settings, and also those children living in the southern regions of the United States.

There was little variation in the insurance status of children hospitalized with CAP between 1997 and 2006. In each of the sampled years, at least 40% of sampled children were privately insured, at least 40% were publicly insured, and approximately 5% were uninsured (Table 1). In all years, there were significant racial/ethnic disparities in insurance coverage such that whites were 4 to 6 times more likely to have private insurance than blacks, however, the large amount of missing race/ethnicity data warrant caution in interpreting this finding (Table 2; also see Supporting Information Appendix B in the online version of this article). We also found that children less than 1 year old were the most likely to be publicly insured in all years (see Supporting Appendix C in the online version of this article). There were also regional differences related to insurance coverage such that a greater proportion of children hospitalized in facilities located in the southern part of the United States were publicly insured. Notably, there were no significant differences in CAP‐associated mortality or asthma related to insurance coverage (Table 2). In 2006, CAP‐associated complications occurred in 8.5% of children with private insurance, 6.5% of children with public insurance, and 7.7% of uninsured children; the relative distribution of complications by insurance type were similar in previous years of the KID survey.

After examining the general and demographic characteristics, we then examined mean LOS for all children with CAP in each sample year (Table 3). The mean LOS for children with CAP was 3.44 days in 1997, with marginal decreases in subsequent years to a mean LOS of 3.18 days in 2006. The distribution of LOS for children with CAP revealed that nearly 70% of children were hospitalized for fewer than 3 days, another 22% to 28% were hospitalized for less than 1 week, and only 3% were hospitalized for more than 1 week. This distribution did not change substantially between 1997 and 2006. Next, we compared mean LOS by insurance type and race/ethnicity in unadjusted analyses. In each sample year, publicly insured children hospitalized with CAP had significantly longer LOS than privately insured children (P < 0.001). Similarly, in all years excepting 1997, uninsured children hospitalized with CAP had significantly shorter LOS than privately insured children. There were also significant racial differences in LOS for children with CAP, such that black children had longer LOS than white children with CAP. However, the large amount of missing data for race/ethnicity limited the robustness of this finding, and subsequent sensitivity analyses demonstrated that there were no consistent racial/ethnic disparities in LOS (see Supporting Appendix B in the online version of this article). These sensitivity analyses for missing race data did not alter our primary finding of shorter LOS for uninsured versus publicly or privately insured children.

After controlling for child age, race/ethnicity, gender, hospital type, transfer status, and presence of asthma or pneumonia‐associated complications, our multivariable analyses examining the relationship between insurance coverage and hospital LOS yielded the following results (Table 4). First, publicly insured children had significantly longer hospital stays than privately insured children, and uninsured children had significantly shorter hospital stays than privately insured children in all years except 1997. Second, children admitted with CAP at urban teaching children's hospitals had significantly longer LOS than those admitted to urban non‐teaching hospitals, and, in 2003, children admitted with CAP to rural hospitals had significantly shorter LOS than those admitted to urban non‐teaching hospitals. Third, children older than 1 year consistently had shorter hospital stays than infants less than 1 year old. Finally, though concomitant diagnosis of asthma did not consistently influence LOS, children who developed any complications had significantly longer LOS than those who did not. The cumulative impact of seemingly small differences in LOS is great. For example, in 2006, our model suggests that, for every 1000 children hospitalized with CAP in a given year, after adjusting for differences in sex, age, race, hospital‐type, region, transfer status, and diagnosis of asthma or complications, publicly insured children spend 90 to 130 more days in the hospital than privately insured children, whereas uninsured children spend between 40 to 90 fewer days in the hospital than privately insured children.

DISCUSSION

In this nationally representative sample selected over the past 10 years, we found that publicly insured children hospitalized with CAP have significantly longer LOS than those who are privately insured, and that, since 2000, uninsured children hospitalized with CAP have significantly shorter LOS than those who are privately insured. Though these observed differences are small, they are consistent across all 4 sampled years and, because CAP is one of the most common pediatric inpatient diagnoses, the cumulative impact of the observed differences on hospital LOS is great. Insurance status is often considered a proxy for access to preventive and ambulatory healthcare services or socioeconomic status. However, the underlying mechanisms relating insurance status to healthcare access, utilization, and ultimately, health outcomes are highly complex and difficult to elucidate.17 The observed variation in this study raises questions about the potential influence of insurance status on hospital discharge practices. Additional research is necessary to understand whether there are differences in processes of care (eg, performance of blood cultures or chest radiographs), quality of care, or other outcomes, such as readmissions, related to CAP inpatient management for children with different insurance coverage.

Apart from differences in hospital discharge practices, another possible explanation for uninsured children with CAP having shorter LOS is that these children have less severe disease than privately insured. This may occur if uninsured children with CAP are evaluated in the emergency department rather than the office setting, because emergency department providers may be more likely to admit children with CAP who lack a consistent access to ambulatory primary care services. Countering this alternative, prior studies have shown that uninsured groups are more likely to have greater disease severity than privately insured groups at the time of hospital admission.18, 19 In this study, we attempted to identify children with greater severity of disease using ICD‐9 codes for CAP‐associated complications. Though this is a relatively crude method that might lead to an underestimate of the total number of children with complications, we found that there were no significant differences in the prevalence of CAP‐associated complications between uninsured and insured groups in all sampled years.

On the other hand, uninsured patients may be released earlier by providers in order to reduce the amount of uncompensated care provided, or possibly because parents may urge providers to discharge their children, given their inability to pay forthcoming hospital bills and/or avoid further lost wages due to work absence.20, 21 In California, Bindman et al. demonstrated that decreasing the frequency of Medicaid recertification, and consequently increasing the likelihood of continuous insurance coverage, was associated with a decreased risk of hospitalization for ambulatory‐care sensitive conditions.5

We also found that children admitted to urban teaching children's hospitals with CAP had significantly longer LOS than those admitted to urban non‐teaching hospitals, whereas children in rural hospitals had significantly shorter LOS than those in urban non‐teaching hospitals in 2003. These findings are consistent with prior data from 1996 to1998 demonstrating that children admitted to rural hospitals in New York and Pennsylvania had significantly shorter LOS than large urban hospitals for 19 medical and 9 surgical conditions, including pneumonia.12 These findings may reflect underlying differences in between rural and urban hospital transfer practices, whereby rural hospitals may be more likely than urban hospitals to transfer children with relatively more severe illness to urban referral centers and retain children with less severe illness, leading to shorter LOS.12 Though our empiric understanding of differences in LOS between teaching and non‐teaching hospitals is currently limited, clinical experience supports the notion that there may be decreases in efficiency that occur in teaching hospitals, and are a result of the supervision required for care provided by trainees. It is also possible that, despite our exclusion of comorbid conditions, some children with complex or chronic medical conditions were included in this study. These children are often cared for at teaching hospitals, regardless of the primary cause for admission, and are more likely to have public insurance than other children, thus confounding the relationship between hospital type, insurance type and status, and LOS for children with CAP. The limitations of this dataset preclude further examination of this issue.

There are some limitations to this study. First, the KID data are cross‐sectional and causal inferences are limited. However, our results demonstrating that uninsured children hospitalized with CAP had shorter LOS than privately insured children were quite consistent in each sample year, suggesting that our results are a true association. Additionally, insurance status in KID is typically collected at admission, however, it is not possible to determine whether specific changes to insurance status that occurred during the hospitalization were applied to the data. The impact of this limitation would depend on the type of insurance obtained by the patient. If uninsured patients obtained public insurance, our study would underestimate the increased LOS for publicly insured patients, compared with privately insured patients, but have no effect on the difference in LOS between uninsured and privately insured patients. In the unlikely event that uninsured patients obtained private insurance, then our study would underestimate the difference for uninsured patients, compared with privately insured patients, biasing our current study results towards the null. Second, a substantial proportion of sampled children had missing data for race/ethnicity. To assess the impact of the missing race/ethnicity data on our results, we conducted sensitivity analyses and found that, though difficult to make any definitive conclusions about the relationship between race/ethnicity and LOS for children with CAP, there were no changes to our primary findings regarding differences in LOS between children with different insurance status and type. Third, KID does not include data about other unmeasured confounders (eg, parent income, parent education, regular source of care) that might be related to LOS, as well as a broad spectrum of pediatric outcomes. Serious consideration of expanding KID to include these variables is warranted. Fourth, the other category of insurance is not uniformly coded across states in the KID database. While some states use this category to classify public insurance options other than Medicare and Medicaid, other states include private insurance options in this group. Thus, it is possible that some patients with public insurance are misclassified as having other insurance. We would expect such misclassification to bias our findings towards the null hypothesis. Finally, we focused on the relationship between child health insurance status and CAP, only 1 ambulatory care‐sensitive condition. Additional research examining the relationship between insurance type and other ambulatory care‐sensitive conditions is warranted.

In summary, we found that, after multivariable adjustment, uninsured children hospitalized with community‐acquired pneumonia had significantly shorter LOS than privately insured children, and publicly insured children had a significantly longer hospital stay than privately insured children in these 4 nationally representative samples from 1997 to 2006. Current federal and state efforts to increase enrollment of children into insurance programs are a first step in reducing healthcare disparities. However, insurance coverage alone does not guarantee access to healthcare, thus, these efforts in isolation will likely be insufficient to achieve optimal health for the children of our country. As healthcare reform legislation is implemented, these findings provide hospitals and policy makers additional impetus to develop ways to achieve the ideal length of stay for every child; this ideal state will be achieved when clinical status and course, rather than nonclinical factors such as insurance type or provider's unease with ambulatory follow‐up, determine the duration of hospitalization for every child.

Disparities in patterns of care and outcomes for ambulatory‐care sensitive conditions remain a persistent problem for children.19 Many studies have focused on disparities in hospitalization rates and length of stay (LOS) related to asthma, however, few studies have focused on community‐acquired pneumonia (CAP) despite the fact that pneumonia is the most common, preventable, and potentially serious infection in childhood.10 Providers, payers, and families have a common interest in minimizing hospital LOS for different reasons (eg, minimizing costs, lost wages, exposure to antibiotic‐resistant bacteria), however, this interest is balanced against the potentially greater risk of readmission and adverse outcomes if LOS is inappropriately short. To date, the relationship between insurance status and LOS for CAP remains unexplored.

As in other conditions, substantial variation exists with respect to patterns of care and outcomes for children hospitalized with CAP.11 For example, children hospitalized in rural settings have a shorter LOS for pneumonia than those hospitalized in large urban settings.12 Children from racial/ethnic minorities tend to have higher rates of CAP‐associated complications, including death.11 Decades of prior studies have documented that uninsured children are less likely than insured children to make preventive care visits and obtain prescription medications, but differences in LOS or hospitalization rates between insured and uninsured children with CAP have not been studied.6, 8, 13, 14 Though imperfect, insurance status is 1 proxy for healthcare access, and current healthcare reform efforts aim to improve healthcare access and decrease socioeconomic gradients in health by increasing the number of insured American children. Nonetheless, quantifying the relationship between insurance status on LOS for children hospitalized with CAP is a first step towards understanding the influence of ambulatory care access on hospitalization for ambulatory‐care sensitive conditions.

The purpose of this study was to investigate the influence of insurance status and type on LOS for children hospitalized with CAP. In addition, we sought to determine if there were consistent trends over time in the association between insurance status and type with LOS for children hospitalized with CAP.

METHODS

RESULTS

The more than 10.5 million children sampled (unweighted) in KID during these 4 time periods (1997, 2000, 2003, and 2006) are representative of the more than 28.9 million children hospitalized in the United States. In each of these sample years, there were approximately 150,000 children hospitalized with pneumonia across the United States (Table 1). Of those hospitalized, 23% to 28% had a concomitant diagnosis of asthma; 6% to 8% had a pneumonia‐associated complication; and mortality was <0.01% in each sample year for patients hospitalized with pneumonia. In all years, among those with racial/ethnic data, the sample population was predominantly white boys less than 6 years old. The greatest proportion of children were hospitalized in urban non‐teaching settings, and also those children living in the southern regions of the United States.

There was little variation in the insurance status of children hospitalized with CAP between 1997 and 2006. In each of the sampled years, at least 40% of sampled children were privately insured, at least 40% were publicly insured, and approximately 5% were uninsured (Table 1). In all years, there were significant racial/ethnic disparities in insurance coverage such that whites were 4 to 6 times more likely to have private insurance than blacks, however, the large amount of missing race/ethnicity data warrant caution in interpreting this finding (Table 2; also see Supporting Information Appendix B in the online version of this article). We also found that children less than 1 year old were the most likely to be publicly insured in all years (see Supporting Appendix C in the online version of this article). There were also regional differences related to insurance coverage such that a greater proportion of children hospitalized in facilities located in the southern part of the United States were publicly insured. Notably, there were no significant differences in CAP‐associated mortality or asthma related to insurance coverage (Table 2). In 2006, CAP‐associated complications occurred in 8.5% of children with private insurance, 6.5% of children with public insurance, and 7.7% of uninsured children; the relative distribution of complications by insurance type were similar in previous years of the KID survey.

After examining the general and demographic characteristics, we then examined mean LOS for all children with CAP in each sample year (Table 3). The mean LOS for children with CAP was 3.44 days in 1997, with marginal decreases in subsequent years to a mean LOS of 3.18 days in 2006. The distribution of LOS for children with CAP revealed that nearly 70% of children were hospitalized for fewer than 3 days, another 22% to 28% were hospitalized for less than 1 week, and only 3% were hospitalized for more than 1 week. This distribution did not change substantially between 1997 and 2006. Next, we compared mean LOS by insurance type and race/ethnicity in unadjusted analyses. In each sample year, publicly insured children hospitalized with CAP had significantly longer LOS than privately insured children (P < 0.001). Similarly, in all years excepting 1997, uninsured children hospitalized with CAP had significantly shorter LOS than privately insured children. There were also significant racial differences in LOS for children with CAP, such that black children had longer LOS than white children with CAP. However, the large amount of missing data for race/ethnicity limited the robustness of this finding, and subsequent sensitivity analyses demonstrated that there were no consistent racial/ethnic disparities in LOS (see Supporting Appendix B in the online version of this article). These sensitivity analyses for missing race data did not alter our primary finding of shorter LOS for uninsured versus publicly or privately insured children.

After controlling for child age, race/ethnicity, gender, hospital type, transfer status, and presence of asthma or pneumonia‐associated complications, our multivariable analyses examining the relationship between insurance coverage and hospital LOS yielded the following results (Table 4). First, publicly insured children had significantly longer hospital stays than privately insured children, and uninsured children had significantly shorter hospital stays than privately insured children in all years except 1997. Second, children admitted with CAP at urban teaching children's hospitals had significantly longer LOS than those admitted to urban non‐teaching hospitals, and, in 2003, children admitted with CAP to rural hospitals had significantly shorter LOS than those admitted to urban non‐teaching hospitals. Third, children older than 1 year consistently had shorter hospital stays than infants less than 1 year old. Finally, though concomitant diagnosis of asthma did not consistently influence LOS, children who developed any complications had significantly longer LOS than those who did not. The cumulative impact of seemingly small differences in LOS is great. For example, in 2006, our model suggests that, for every 1000 children hospitalized with CAP in a given year, after adjusting for differences in sex, age, race, hospital‐type, region, transfer status, and diagnosis of asthma or complications, publicly insured children spend 90 to 130 more days in the hospital than privately insured children, whereas uninsured children spend between 40 to 90 fewer days in the hospital than privately insured children.

DISCUSSION

In this nationally representative sample selected over the past 10 years, we found that publicly insured children hospitalized with CAP have significantly longer LOS than those who are privately insured, and that, since 2000, uninsured children hospitalized with CAP have significantly shorter LOS than those who are privately insured. Though these observed differences are small, they are consistent across all 4 sampled years and, because CAP is one of the most common pediatric inpatient diagnoses, the cumulative impact of the observed differences on hospital LOS is great. Insurance status is often considered a proxy for access to preventive and ambulatory healthcare services or socioeconomic status. However, the underlying mechanisms relating insurance status to healthcare access, utilization, and ultimately, health outcomes are highly complex and difficult to elucidate.17 The observed variation in this study raises questions about the potential influence of insurance status on hospital discharge practices. Additional research is necessary to understand whether there are differences in processes of care (eg, performance of blood cultures or chest radiographs), quality of care, or other outcomes, such as readmissions, related to CAP inpatient management for children with different insurance coverage.

Apart from differences in hospital discharge practices, another possible explanation for uninsured children with CAP having shorter LOS is that these children have less severe disease than privately insured. This may occur if uninsured children with CAP are evaluated in the emergency department rather than the office setting, because emergency department providers may be more likely to admit children with CAP who lack a consistent access to ambulatory primary care services. Countering this alternative, prior studies have shown that uninsured groups are more likely to have greater disease severity than privately insured groups at the time of hospital admission.18, 19 In this study, we attempted to identify children with greater severity of disease using ICD‐9 codes for CAP‐associated complications. Though this is a relatively crude method that might lead to an underestimate of the total number of children with complications, we found that there were no significant differences in the prevalence of CAP‐associated complications between uninsured and insured groups in all sampled years.

On the other hand, uninsured patients may be released earlier by providers in order to reduce the amount of uncompensated care provided, or possibly because parents may urge providers to discharge their children, given their inability to pay forthcoming hospital bills and/or avoid further lost wages due to work absence.20, 21 In California, Bindman et al. demonstrated that decreasing the frequency of Medicaid recertification, and consequently increasing the likelihood of continuous insurance coverage, was associated with a decreased risk of hospitalization for ambulatory‐care sensitive conditions.5

We also found that children admitted to urban teaching children's hospitals with CAP had significantly longer LOS than those admitted to urban non‐teaching hospitals, whereas children in rural hospitals had significantly shorter LOS than those in urban non‐teaching hospitals in 2003. These findings are consistent with prior data from 1996 to1998 demonstrating that children admitted to rural hospitals in New York and Pennsylvania had significantly shorter LOS than large urban hospitals for 19 medical and 9 surgical conditions, including pneumonia.12 These findings may reflect underlying differences in between rural and urban hospital transfer practices, whereby rural hospitals may be more likely than urban hospitals to transfer children with relatively more severe illness to urban referral centers and retain children with less severe illness, leading to shorter LOS.12 Though our empiric understanding of differences in LOS between teaching and non‐teaching hospitals is currently limited, clinical experience supports the notion that there may be decreases in efficiency that occur in teaching hospitals, and are a result of the supervision required for care provided by trainees. It is also possible that, despite our exclusion of comorbid conditions, some children with complex or chronic medical conditions were included in this study. These children are often cared for at teaching hospitals, regardless of the primary cause for admission, and are more likely to have public insurance than other children, thus confounding the relationship between hospital type, insurance type and status, and LOS for children with CAP. The limitations of this dataset preclude further examination of this issue.

There are some limitations to this study. First, the KID data are cross‐sectional and causal inferences are limited. However, our results demonstrating that uninsured children hospitalized with CAP had shorter LOS than privately insured children were quite consistent in each sample year, suggesting that our results are a true association. Additionally, insurance status in KID is typically collected at admission, however, it is not possible to determine whether specific changes to insurance status that occurred during the hospitalization were applied to the data. The impact of this limitation would depend on the type of insurance obtained by the patient. If uninsured patients obtained public insurance, our study would underestimate the increased LOS for publicly insured patients, compared with privately insured patients, but have no effect on the difference in LOS between uninsured and privately insured patients. In the unlikely event that uninsured patients obtained private insurance, then our study would underestimate the difference for uninsured patients, compared with privately insured patients, biasing our current study results towards the null. Second, a substantial proportion of sampled children had missing data for race/ethnicity. To assess the impact of the missing race/ethnicity data on our results, we conducted sensitivity analyses and found that, though difficult to make any definitive conclusions about the relationship between race/ethnicity and LOS for children with CAP, there were no changes to our primary findings regarding differences in LOS between children with different insurance status and type. Third, KID does not include data about other unmeasured confounders (eg, parent income, parent education, regular source of care) that might be related to LOS, as well as a broad spectrum of pediatric outcomes. Serious consideration of expanding KID to include these variables is warranted. Fourth, the other category of insurance is not uniformly coded across states in the KID database. While some states use this category to classify public insurance options other than Medicare and Medicaid, other states include private insurance options in this group. Thus, it is possible that some patients with public insurance are misclassified as having other insurance. We would expect such misclassification to bias our findings towards the null hypothesis. Finally, we focused on the relationship between child health insurance status and CAP, only 1 ambulatory care‐sensitive condition. Additional research examining the relationship between insurance type and other ambulatory care‐sensitive conditions is warranted.

In summary, we found that, after multivariable adjustment, uninsured children hospitalized with community‐acquired pneumonia had significantly shorter LOS than privately insured children, and publicly insured children had a significantly longer hospital stay than privately insured children in these 4 nationally representative samples from 1997 to 2006. Current federal and state efforts to increase enrollment of children into insurance programs are a first step in reducing healthcare disparities. However, insurance coverage alone does not guarantee access to healthcare, thus, these efforts in isolation will likely be insufficient to achieve optimal health for the children of our country. As healthcare reform legislation is implemented, these findings provide hospitals and policy makers additional impetus to develop ways to achieve the ideal length of stay for every child; this ideal state will be achieved when clinical status and course, rather than nonclinical factors such as insurance type or provider's unease with ambulatory follow‐up, determine the duration of hospitalization for every child.

Herpes simplex virus (HSV) is a significant cause of pediatric hospitalization, morbidity and mortality, particularly in infants under 60 days of age, where HSV can present as meningoencephalitis, skin disease, or sepsis.14 Most prior studies use data from registries taken from single centers or a restricted group of hospitals. Thus, there is a paucity of recent, nationally‐representative information about the outcome of infants infected with HSV, especially those treated at nonteaching hospitals or with rarer comorbid conditions. The goal of this project was to determine the patient and hospital characteristics associated with worse clinical outcomes in infants under the age of 60 days admitted with HSV disease. We hypothesized that younger infants, infants with a concurrent congenital anomaly, and infants treated at non‐children's hospitals would have worse clinical outcomes. To answer these questions, we used 2003 panel data from the Healthcare Cost and Utilization Project (HCUP) Kids' Inpatient Database (KID), a nationally representative sample of inpatient hospitalizations in the United States.

Methods

Results

The 2003 KID identified 1587 hospitalizations for HSV in infants admitted at an age of 60 days or less in the entire United States. These infants had a total hospital cost of $27,147,000. Of the cohort, 10% had a concurrent congenital anomaly. Most infants (73.5%) were admitted within 14 days of birth, and 15.5% were transferred from another hospital. Based on APR‐DRG criteria, 33% of the infants were classified as having a moderate risk of death, 24% as major risk, and 12.2% as extreme risk. The majority of infants were treated at non‐children's hospitals (85.3%) in urban locations (91.5%). The average LOS was 12.0 0.6 days and the average total hospital cost was $17,382 1269. After admission, 267 of the infants, or 16.8%, had at least 1 serious complication. Fifty infants died during the hospitalization included in the KID.

Conclusions

There has been little prior information to guide practitioners and parents about factors that potentially influence clinical outcome of infants hospitalized with HSV in non‐children's hospitals, although over 80% of infants are managed at non‐children's hospitals. These studies also did not have the power to characterize the risk of poor clinical outcome associated with rarer clinical factors.1, 2, 6 This study, using nationally representative data, found that these rarer clinical factors and site of care may influence the outcomes of infants hospitalized with HSV, albeit in different methods. Younger age at admission and a coexisting congenital anomaly remained statistically significant predictors of worse clinical outcomes after controlling for various patient and hospital factors. Not all congenital anomalies increased the risk of death or serious complications; rather, anomalies that affected either the cardiopulmonary system or the central nervous system appeared to result in the highest increases in risk. This study also found that treatment of infants with HSV at a children's hospital was associated with a 28% shorter LOS after accounting for the sicker patients cared for by children's hospitals. This finding is in contrast to prior studies of common pediatric conditions, where there were no differences in the LOS between children's and non‐children's hospitals,17, 18 and severe sepsis, where children's hospitals had longer LOSs.19 These results confirm the importance of specific risk factors in predicting the likelihood that an infant admitted with HSV may have a poor clinical outcome. Also, these results emphasize the differences in outcomes that may occur at different types of hospitals.

This study is the first to find that certain congenital anomalies or conditions may be associated with worse clinical outcomes from HSV. There is little information in the literature to explain these findings. Those anomalies that affect the cardiopulmonary or central nervous system may either worsen the symptoms of HSV or predispose infants to have a serious complication, such as shock or respiratory failure. This finding would be similar to the increased risk of serious complications seen in infants with congenital heart disease who contract respiratory syncytial virus20 or infants with genetic syndromes who undergo heart surgery.21 Alternatively, because we do not have information on do‐not‐resuscitate status, the presence of one of these congenital anomalies may result in more withdrawal of care when an infant is infected with HSV and has a serious complication; the LOS of these children may not reflect these decisions because the decision to withdrawal care may only occur after the child's condition worsens significantly, which may happen any time during the disease course. However, this theory is less likely because we failed to find similar results with other congenital anomalies such as genetic or chromosomal syndromes. Further examination of these infants and their overall response to insults such as HSV is needed to understand how these anomalies influence the outcomes of a serious, unrelated illness.

Age upon admission was another important predictor of poor outcomes when analyzed in univariable or multivariable analysis. This result is consistent with prior work,14 which suggests that younger children are more likely to be hospitalized with either congenitally acquired HSV or systemic disease. The information contained in the KID does not allow us to determine whether young age is a risk factor for poor outcome irrespective of the clinical presentation of HSV, or whether age serves as a proxy for the appearance of more severe clinical disease. This effect of age remained present even after controlling for the higher risk of a serious complication and death in low birth weight infants. There are limited data that suggest that premature birth is an independent risk factor for worse outcomes associated with perinatal or congenital infection; 1 previous case study of Enterobacter sakazakii infections found a higher fatality rate for premature infants compared to term infants.22 This study supports these findings.

This study found that treatment at a children's hospital resulted in a 28% shorter LOS without a statistically significant difference in clinical outcomes after controlling for case‐mix differences. This finding is in contrast to prior studies of common pediatric conditions17, 18 and severe sepsis.19 There are several potential explanations for the difference in findings. For common pediatric conditions, there may be fewer variations in treatment style and less need for new diagnostic modalities that are more available at academic centers. For HSV disease, though, children's hospitals may also be more likely than non‐children's hospitals to perform polymerase‐chain reaction (PCR) testing for the diagnosis of perinatally acquired HSV, correctly identify the disorder, or receive the test results in a timely fashion. Pediatric subspecialists, such as infectious disease physicians or neurologists, are also likely to be more available at children's hospitals than at other centers. While the role of subspecialty consultation in improving outcomes for neonates with HSV is not known, improved outcomes at children's hospitals has been described for other serious conditions such as splenic injuries.23 Children's hospitals had higher daily costs than non‐children's hospitals, as has been found in other work.17, 19 Children's hospitals may be treating sicker patients, for whom we are unable to adequately adjust for their illness severity with hospital administrative data.17, 19 Also, there may be a greater use of medical tests and treatments that increase the costs of care. These costs do not include indirect costs to the families such as loss of work and travel costs. In light of the shorter LOS in children's hospitals, policy makers will need to balance the potentially higher daily costs of care with more efficient management of the disease process.

Because this study used hospital administrative records, there are a few limitations. We used ICD‐9CM diagnosis codes to identify patients, congenital anomalies, and complications. The diagnosis of some infants with HSV or less significant congenital anomalies could have been missed because clinicians either overlooked the disease or did not make the diagnosis before discharge. This form of spectrum bias would likely miss the infants with the least severe disease and make it more difficult to find the results that we found in this study.24 Prior work successfully used and validated similar ICD‐9CM codes to identify HSV cases among the different types of hospitals included in the KID.611 Our study design estimated 1587 cases of neonatal HSV in 2003. A prospective study of maternal serologic and virologic status during pregnancy estimated 480 to 2160 new cases of neonatal HSV per year.25 Thus, while miscoding is a potential limitation to our study, the overall numbers of patients in this study were similar to past annual estimates. One potential area of miscounting, though, was the inability of the KID to link the records of 16% of the identified infants with HSV whose care was transferred between hospitals. These infants may result in misleading LOS or cost information: lower for the transferring hospital, because they only kept the child a short period of time, or lower for the accepting hospital, as some of the total hospital stay is not accounted for in the KID. We accounted for this issue in 2 ways. First, we included a variable for being transferred in the multivariable models, and found no difference in any results when we omitted these patients from the analysis. Second, we performed a univariable analysis stratified by transfer status, which did not differ substantially from our main model for most variables. Accurate linkage of all the hospital records for an infant's hospital course, likely only through a mandatory reporting system for infant HSV, would help confirm the associations we identified in this study.

In conclusion, infants with congenital anomalies should be closely monitored for the development of serious complications associated with HSV, particularly those infants with congenital heart disease, pulmonary anomalies, or central nervous system anomalies. Closer investigation of the care practices that children's hospitals use in the management of infants with HSV is needed to improve the efficiency of care delivered to these infants, as HSV disease remains a significant public health problem.

Herpes simplex virus (HSV) is a significant cause of pediatric hospitalization, morbidity and mortality, particularly in infants under 60 days of age, where HSV can present as meningoencephalitis, skin disease, or sepsis.14 Most prior studies use data from registries taken from single centers or a restricted group of hospitals. Thus, there is a paucity of recent, nationally‐representative information about the outcome of infants infected with HSV, especially those treated at nonteaching hospitals or with rarer comorbid conditions. The goal of this project was to determine the patient and hospital characteristics associated with worse clinical outcomes in infants under the age of 60 days admitted with HSV disease. We hypothesized that younger infants, infants with a concurrent congenital anomaly, and infants treated at non‐children's hospitals would have worse clinical outcomes. To answer these questions, we used 2003 panel data from the Healthcare Cost and Utilization Project (HCUP) Kids' Inpatient Database (KID), a nationally representative sample of inpatient hospitalizations in the United States.

Methods

Results

The 2003 KID identified 1587 hospitalizations for HSV in infants admitted at an age of 60 days or less in the entire United States. These infants had a total hospital cost of $27,147,000. Of the cohort, 10% had a concurrent congenital anomaly. Most infants (73.5%) were admitted within 14 days of birth, and 15.5% were transferred from another hospital. Based on APR‐DRG criteria, 33% of the infants were classified as having a moderate risk of death, 24% as major risk, and 12.2% as extreme risk. The majority of infants were treated at non‐children's hospitals (85.3%) in urban locations (91.5%). The average LOS was 12.0 0.6 days and the average total hospital cost was $17,382 1269. After admission, 267 of the infants, or 16.8%, had at least 1 serious complication. Fifty infants died during the hospitalization included in the KID.

Conclusions

There has been little prior information to guide practitioners and parents about factors that potentially influence clinical outcome of infants hospitalized with HSV in non‐children's hospitals, although over 80% of infants are managed at non‐children's hospitals. These studies also did not have the power to characterize the risk of poor clinical outcome associated with rarer clinical factors.1, 2, 6 This study, using nationally representative data, found that these rarer clinical factors and site of care may influence the outcomes of infants hospitalized with HSV, albeit in different methods. Younger age at admission and a coexisting congenital anomaly remained statistically significant predictors of worse clinical outcomes after controlling for various patient and hospital factors. Not all congenital anomalies increased the risk of death or serious complications; rather, anomalies that affected either the cardiopulmonary system or the central nervous system appeared to result in the highest increases in risk. This study also found that treatment of infants with HSV at a children's hospital was associated with a 28% shorter LOS after accounting for the sicker patients cared for by children's hospitals. This finding is in contrast to prior studies of common pediatric conditions, where there were no differences in the LOS between children's and non‐children's hospitals,17, 18 and severe sepsis, where children's hospitals had longer LOSs.19 These results confirm the importance of specific risk factors in predicting the likelihood that an infant admitted with HSV may have a poor clinical outcome. Also, these results emphasize the differences in outcomes that may occur at different types of hospitals.

This study is the first to find that certain congenital anomalies or conditions may be associated with worse clinical outcomes from HSV. There is little information in the literature to explain these findings. Those anomalies that affect the cardiopulmonary or central nervous system may either worsen the symptoms of HSV or predispose infants to have a serious complication, such as shock or respiratory failure. This finding would be similar to the increased risk of serious complications seen in infants with congenital heart disease who contract respiratory syncytial virus20 or infants with genetic syndromes who undergo heart surgery.21 Alternatively, because we do not have information on do‐not‐resuscitate status, the presence of one of these congenital anomalies may result in more withdrawal of care when an infant is infected with HSV and has a serious complication; the LOS of these children may not reflect these decisions because the decision to withdrawal care may only occur after the child's condition worsens significantly, which may happen any time during the disease course. However, this theory is less likely because we failed to find similar results with other congenital anomalies such as genetic or chromosomal syndromes. Further examination of these infants and their overall response to insults such as HSV is needed to understand how these anomalies influence the outcomes of a serious, unrelated illness.

Age upon admission was another important predictor of poor outcomes when analyzed in univariable or multivariable analysis. This result is consistent with prior work,14 which suggests that younger children are more likely to be hospitalized with either congenitally acquired HSV or systemic disease. The information contained in the KID does not allow us to determine whether young age is a risk factor for poor outcome irrespective of the clinical presentation of HSV, or whether age serves as a proxy for the appearance of more severe clinical disease. This effect of age remained present even after controlling for the higher risk of a serious complication and death in low birth weight infants. There are limited data that suggest that premature birth is an independent risk factor for worse outcomes associated with perinatal or congenital infection; 1 previous case study of Enterobacter sakazakii infections found a higher fatality rate for premature infants compared to term infants.22 This study supports these findings.

This study found that treatment at a children's hospital resulted in a 28% shorter LOS without a statistically significant difference in clinical outcomes after controlling for case‐mix differences. This finding is in contrast to prior studies of common pediatric conditions17, 18 and severe sepsis.19 There are several potential explanations for the difference in findings. For common pediatric conditions, there may be fewer variations in treatment style and less need for new diagnostic modalities that are more available at academic centers. For HSV disease, though, children's hospitals may also be more likely than non‐children's hospitals to perform polymerase‐chain reaction (PCR) testing for the diagnosis of perinatally acquired HSV, correctly identify the disorder, or receive the test results in a timely fashion. Pediatric subspecialists, such as infectious disease physicians or neurologists, are also likely to be more available at children's hospitals than at other centers. While the role of subspecialty consultation in improving outcomes for neonates with HSV is not known, improved outcomes at children's hospitals has been described for other serious conditions such as splenic injuries.23 Children's hospitals had higher daily costs than non‐children's hospitals, as has been found in other work.17, 19 Children's hospitals may be treating sicker patients, for whom we are unable to adequately adjust for their illness severity with hospital administrative data.17, 19 Also, there may be a greater use of medical tests and treatments that increase the costs of care. These costs do not include indirect costs to the families such as loss of work and travel costs. In light of the shorter LOS in children's hospitals, policy makers will need to balance the potentially higher daily costs of care with more efficient management of the disease process.

Because this study used hospital administrative records, there are a few limitations. We used ICD‐9CM diagnosis codes to identify patients, congenital anomalies, and complications. The diagnosis of some infants with HSV or less significant congenital anomalies could have been missed because clinicians either overlooked the disease or did not make the diagnosis before discharge. This form of spectrum bias would likely miss the infants with the least severe disease and make it more difficult to find the results that we found in this study.24 Prior work successfully used and validated similar ICD‐9CM codes to identify HSV cases among the different types of hospitals included in the KID.611 Our study design estimated 1587 cases of neonatal HSV in 2003. A prospective study of maternal serologic and virologic status during pregnancy estimated 480 to 2160 new cases of neonatal HSV per year.25 Thus, while miscoding is a potential limitation to our study, the overall numbers of patients in this study were similar to past annual estimates. One potential area of miscounting, though, was the inability of the KID to link the records of 16% of the identified infants with HSV whose care was transferred between hospitals. These infants may result in misleading LOS or cost information: lower for the transferring hospital, because they only kept the child a short period of time, or lower for the accepting hospital, as some of the total hospital stay is not accounted for in the KID. We accounted for this issue in 2 ways. First, we included a variable for being transferred in the multivariable models, and found no difference in any results when we omitted these patients from the analysis. Second, we performed a univariable analysis stratified by transfer status, which did not differ substantially from our main model for most variables. Accurate linkage of all the hospital records for an infant's hospital course, likely only through a mandatory reporting system for infant HSV, would help confirm the associations we identified in this study.

In conclusion, infants with congenital anomalies should be closely monitored for the development of serious complications associated with HSV, particularly those infants with congenital heart disease, pulmonary anomalies, or central nervous system anomalies. Closer investigation of the care practices that children's hospitals use in the management of infants with HSV is needed to improve the efficiency of care delivered to these infants, as HSV disease remains a significant public health problem.

Herpes simplex virus (HSV) is a significant cause of pediatric hospitalization, morbidity and mortality, particularly in infants under 60 days of age, where HSV can present as meningoencephalitis, skin disease, or sepsis.14 Most prior studies use data from registries taken from single centers or a restricted group of hospitals. Thus, there is a paucity of recent, nationally‐representative information about the outcome of infants infected with HSV, especially those treated at nonteaching hospitals or with rarer comorbid conditions. The goal of this project was to determine the patient and hospital characteristics associated with worse clinical outcomes in infants under the age of 60 days admitted with HSV disease. We hypothesized that younger infants, infants with a concurrent congenital anomaly, and infants treated at non‐children's hospitals would have worse clinical outcomes. To answer these questions, we used 2003 panel data from the Healthcare Cost and Utilization Project (HCUP) Kids' Inpatient Database (KID), a nationally representative sample of inpatient hospitalizations in the United States.

Methods

Results

The 2003 KID identified 1587 hospitalizations for HSV in infants admitted at an age of 60 days or less in the entire United States. These infants had a total hospital cost of $27,147,000. Of the cohort, 10% had a concurrent congenital anomaly. Most infants (73.5%) were admitted within 14 days of birth, and 15.5% were transferred from another hospital. Based on APR‐DRG criteria, 33% of the infants were classified as having a moderate risk of death, 24% as major risk, and 12.2% as extreme risk. The majority of infants were treated at non‐children's hospitals (85.3%) in urban locations (91.5%). The average LOS was 12.0 0.6 days and the average total hospital cost was $17,382 1269. After admission, 267 of the infants, or 16.8%, had at least 1 serious complication. Fifty infants died during the hospitalization included in the KID.

Conclusions

There has been little prior information to guide practitioners and parents about factors that potentially influence clinical outcome of infants hospitalized with HSV in non‐children's hospitals, although over 80% of infants are managed at non‐children's hospitals. These studies also did not have the power to characterize the risk of poor clinical outcome associated with rarer clinical factors.1, 2, 6 This study, using nationally representative data, found that these rarer clinical factors and site of care may influence the outcomes of infants hospitalized with HSV, albeit in different methods. Younger age at admission and a coexisting congenital anomaly remained statistically significant predictors of worse clinical outcomes after controlling for various patient and hospital factors. Not all congenital anomalies increased the risk of death or serious complications; rather, anomalies that affected either the cardiopulmonary system or the central nervous system appeared to result in the highest increases in risk. This study also found that treatment of infants with HSV at a children's hospital was associated with a 28% shorter LOS after accounting for the sicker patients cared for by children's hospitals. This finding is in contrast to prior studies of common pediatric conditions, where there were no differences in the LOS between children's and non‐children's hospitals,17, 18 and severe sepsis, where children's hospitals had longer LOSs.19 These results confirm the importance of specific risk factors in predicting the likelihood that an infant admitted with HSV may have a poor clinical outcome. Also, these results emphasize the differences in outcomes that may occur at different types of hospitals.

This study is the first to find that certain congenital anomalies or conditions may be associated with worse clinical outcomes from HSV. There is little information in the literature to explain these findings. Those anomalies that affect the cardiopulmonary or central nervous system may either worsen the symptoms of HSV or predispose infants to have a serious complication, such as shock or respiratory failure. This finding would be similar to the increased risk of serious complications seen in infants with congenital heart disease who contract respiratory syncytial virus20 or infants with genetic syndromes who undergo heart surgery.21 Alternatively, because we do not have information on do‐not‐resuscitate status, the presence of one of these congenital anomalies may result in more withdrawal of care when an infant is infected with HSV and has a serious complication; the LOS of these children may not reflect these decisions because the decision to withdrawal care may only occur after the child's condition worsens significantly, which may happen any time during the disease course. However, this theory is less likely because we failed to find similar results with other congenital anomalies such as genetic or chromosomal syndromes. Further examination of these infants and their overall response to insults such as HSV is needed to understand how these anomalies influence the outcomes of a serious, unrelated illness.

Age upon admission was another important predictor of poor outcomes when analyzed in univariable or multivariable analysis. This result is consistent with prior work,14 which suggests that younger children are more likely to be hospitalized with either congenitally acquired HSV or systemic disease. The information contained in the KID does not allow us to determine whether young age is a risk factor for poor outcome irrespective of the clinical presentation of HSV, or whether age serves as a proxy for the appearance of more severe clinical disease. This effect of age remained present even after controlling for the higher risk of a serious complication and death in low birth weight infants. There are limited data that suggest that premature birth is an independent risk factor for worse outcomes associated with perinatal or congenital infection; 1 previous case study of Enterobacter sakazakii infections found a higher fatality rate for premature infants compared to term infants.22 This study supports these findings.

This study found that treatment at a children's hospital resulted in a 28% shorter LOS without a statistically significant difference in clinical outcomes after controlling for case‐mix differences. This finding is in contrast to prior studies of common pediatric conditions17, 18 and severe sepsis.19 There are several potential explanations for the difference in findings. For common pediatric conditions, there may be fewer variations in treatment style and less need for new diagnostic modalities that are more available at academic centers. For HSV disease, though, children's hospitals may also be more likely than non‐children's hospitals to perform polymerase‐chain reaction (PCR) testing for the diagnosis of perinatally acquired HSV, correctly identify the disorder, or receive the test results in a timely fashion. Pediatric subspecialists, such as infectious disease physicians or neurologists, are also likely to be more available at children's hospitals than at other centers. While the role of subspecialty consultation in improving outcomes for neonates with HSV is not known, improved outcomes at children's hospitals has been described for other serious conditions such as splenic injuries.23 Children's hospitals had higher daily costs than non‐children's hospitals, as has been found in other work.17, 19 Children's hospitals may be treating sicker patients, for whom we are unable to adequately adjust for their illness severity with hospital administrative data.17, 19 Also, there may be a greater use of medical tests and treatments that increase the costs of care. These costs do not include indirect costs to the families such as loss of work and travel costs. In light of the shorter LOS in children's hospitals, policy makers will need to balance the potentially higher daily costs of care with more efficient management of the disease process.

Because this study used hospital administrative records, there are a few limitations. We used ICD‐9CM diagnosis codes to identify patients, congenital anomalies, and complications. The diagnosis of some infants with HSV or less significant congenital anomalies could have been missed because clinicians either overlooked the disease or did not make the diagnosis before discharge. This form of spectrum bias would likely miss the infants with the least severe disease and make it more difficult to find the results that we found in this study.24 Prior work successfully used and validated similar ICD‐9CM codes to identify HSV cases among the different types of hospitals included in the KID.611 Our study design estimated 1587 cases of neonatal HSV in 2003. A prospective study of maternal serologic and virologic status during pregnancy estimated 480 to 2160 new cases of neonatal HSV per year.25 Thus, while miscoding is a potential limitation to our study, the overall numbers of patients in this study were similar to past annual estimates. One potential area of miscounting, though, was the inability of the KID to link the records of 16% of the identified infants with HSV whose care was transferred between hospitals. These infants may result in misleading LOS or cost information: lower for the transferring hospital, because they only kept the child a short period of time, or lower for the accepting hospital, as some of the total hospital stay is not accounted for in the KID. We accounted for this issue in 2 ways. First, we included a variable for being transferred in the multivariable models, and found no difference in any results when we omitted these patients from the analysis. Second, we performed a univariable analysis stratified by transfer status, which did not differ substantially from our main model for most variables. Accurate linkage of all the hospital records for an infant's hospital course, likely only through a mandatory reporting system for infant HSV, would help confirm the associations we identified in this study.

In conclusion, infants with congenital anomalies should be closely monitored for the development of serious complications associated with HSV, particularly those infants with congenital heart disease, pulmonary anomalies, or central nervous system anomalies. Closer investigation of the care practices that children's hospitals use in the management of infants with HSV is needed to improve the efficiency of care delivered to these infants, as HSV disease remains a significant public health problem.