Jordan Derk, BS

After reading the letter to the editor from Neil Goldfarb, we are concerned that the focus of our study[1] was misinterpreted. Upon reviewing the methodology for Leapfrog's Hospital Safety Score in May 2013, we were surprised to find that Leapfrog uses 2 separate scoring methodologies, depending on whether the hospital participates in the Leapfrog Hospital Survey. Survey participants are scored from 26 measures, whereas nonparticipants are scored from only 18 measures3 of which are imputed from other data sourceswith recalibrated weightings for each measure. Measuring and publicly disclosing hospital information are paramount to improving safety and quality, and we applaud Leapfrog for taking a leading role in this. However, our report demonstrated that Leapfrog's Hospital Safety Score, which was attained through 2 separate methodologies, may result in unintended inconsistency or misinterpretation.

We believe Mr. Goldfarb misunderstood our notion of statistical significance. In the report, we acknowledged that the mean score differences between participating and nonparticipating hospitals in our sample were not statistically significant, possibly due to small sample size. However, this was not the focus of our report. Utilizing a mean imputation approach, we rescored the nonparticipating hospitals in our sample as if they had participated in the Leapfrog Hospital Survey. The differences between the original nonparticipant scores and their respective participant estimations were not statistically significant. However, due to the cutoff points Leapfrog uses to assign letter grades, these differences resulted in a letter grade change for many of the nonparticipating hospitals in our sample.

We wish to clarify that a hospital's choice to participate or not to participate in the Leapfrog Hospital Survey is not a reflection of their willingness to promote patient safety. Hospitals voluntarily report data to numerous private organizations and are required to report hundreds of quality and safety measures to government agencies. The 26 (or 18) measures included in Leapfrog's Hospital Safety Score are merely a fraction of the measures hospitals already report.

Finally, we regret that our brief report has been mischaracterized by Neil Goldfarb as being clearly biased against the work of the Leapfrog Group. This is far from our intent. Throughout the manuscript, we repeatedly acknowledge Leapfrog's contribution in patient safety improvement; our work does not intend to discredit Leapfrog's hard‐earned reputation. We provide a recommendation that Leapfrog produce 2 separate reports for participating and nonparticipating hospitals to maintain clarity. Our research has followed academic protocol, has undergone a stringent peer‐review process, and included full disclosure of any potential conflicts of interest. We hope our analysis will contribute to the continuing improvement of Leapfrog's hospital patient safety reporting.

After reading the letter to the editor from Neil Goldfarb, we are concerned that the focus of our study[1] was misinterpreted. Upon reviewing the methodology for Leapfrog's Hospital Safety Score in May 2013, we were surprised to find that Leapfrog uses 2 separate scoring methodologies, depending on whether the hospital participates in the Leapfrog Hospital Survey. Survey participants are scored from 26 measures, whereas nonparticipants are scored from only 18 measures3 of which are imputed from other data sourceswith recalibrated weightings for each measure. Measuring and publicly disclosing hospital information are paramount to improving safety and quality, and we applaud Leapfrog for taking a leading role in this. However, our report demonstrated that Leapfrog's Hospital Safety Score, which was attained through 2 separate methodologies, may result in unintended inconsistency or misinterpretation.

We believe Mr. Goldfarb misunderstood our notion of statistical significance. In the report, we acknowledged that the mean score differences between participating and nonparticipating hospitals in our sample were not statistically significant, possibly due to small sample size. However, this was not the focus of our report. Utilizing a mean imputation approach, we rescored the nonparticipating hospitals in our sample as if they had participated in the Leapfrog Hospital Survey. The differences between the original nonparticipant scores and their respective participant estimations were not statistically significant. However, due to the cutoff points Leapfrog uses to assign letter grades, these differences resulted in a letter grade change for many of the nonparticipating hospitals in our sample.

We wish to clarify that a hospital's choice to participate or not to participate in the Leapfrog Hospital Survey is not a reflection of their willingness to promote patient safety. Hospitals voluntarily report data to numerous private organizations and are required to report hundreds of quality and safety measures to government agencies. The 26 (or 18) measures included in Leapfrog's Hospital Safety Score are merely a fraction of the measures hospitals already report.

Finally, we regret that our brief report has been mischaracterized by Neil Goldfarb as being clearly biased against the work of the Leapfrog Group. This is far from our intent. Throughout the manuscript, we repeatedly acknowledge Leapfrog's contribution in patient safety improvement; our work does not intend to discredit Leapfrog's hard‐earned reputation. We provide a recommendation that Leapfrog produce 2 separate reports for participating and nonparticipating hospitals to maintain clarity. Our research has followed academic protocol, has undergone a stringent peer‐review process, and included full disclosure of any potential conflicts of interest. We hope our analysis will contribute to the continuing improvement of Leapfrog's hospital patient safety reporting.

After reading the letter to the editor from Neil Goldfarb, we are concerned that the focus of our study[1] was misinterpreted. Upon reviewing the methodology for Leapfrog's Hospital Safety Score in May 2013, we were surprised to find that Leapfrog uses 2 separate scoring methodologies, depending on whether the hospital participates in the Leapfrog Hospital Survey. Survey participants are scored from 26 measures, whereas nonparticipants are scored from only 18 measures3 of which are imputed from other data sourceswith recalibrated weightings for each measure. Measuring and publicly disclosing hospital information are paramount to improving safety and quality, and we applaud Leapfrog for taking a leading role in this. However, our report demonstrated that Leapfrog's Hospital Safety Score, which was attained through 2 separate methodologies, may result in unintended inconsistency or misinterpretation.

We believe Mr. Goldfarb misunderstood our notion of statistical significance. In the report, we acknowledged that the mean score differences between participating and nonparticipating hospitals in our sample were not statistically significant, possibly due to small sample size. However, this was not the focus of our report. Utilizing a mean imputation approach, we rescored the nonparticipating hospitals in our sample as if they had participated in the Leapfrog Hospital Survey. The differences between the original nonparticipant scores and their respective participant estimations were not statistically significant. However, due to the cutoff points Leapfrog uses to assign letter grades, these differences resulted in a letter grade change for many of the nonparticipating hospitals in our sample.

We wish to clarify that a hospital's choice to participate or not to participate in the Leapfrog Hospital Survey is not a reflection of their willingness to promote patient safety. Hospitals voluntarily report data to numerous private organizations and are required to report hundreds of quality and safety measures to government agencies. The 26 (or 18) measures included in Leapfrog's Hospital Safety Score are merely a fraction of the measures hospitals already report.

Finally, we regret that our brief report has been mischaracterized by Neil Goldfarb as being clearly biased against the work of the Leapfrog Group. This is far from our intent. Throughout the manuscript, we repeatedly acknowledge Leapfrog's contribution in patient safety improvement; our work does not intend to discredit Leapfrog's hard‐earned reputation. We provide a recommendation that Leapfrog produce 2 separate reports for participating and nonparticipating hospitals to maintain clarity. Our research has followed academic protocol, has undergone a stringent peer‐review process, and included full disclosure of any potential conflicts of interest. We hope our analysis will contribute to the continuing improvement of Leapfrog's hospital patient safety reporting.

The Institute of Medicine (IOM) reported over a decade ago that between 44,000 and 98,000 deaths occurred every year due to preventable medical errors.[1] The report sparked an intense interest in identifying, measuring, and reporting hospital performance in patient safety.[2] The report also sparked the implementation of many initiatives aiming to improve patient safety.[3] Despite these efforts, there is still much room for improvement in the area of patient safety.[4] As the public has become more aware of patient safety issues, there has been an increased demand for information on hospital safety. The Leapfrog Group, a leading organization that examines and reports on hospital performance in patient safety, cites the IOM report as providing the focus that their newly formed organization required.[5]

Using 26 national measures of safety, The Leapfrog Group calculates a numeric Hospital Safety Score for over 2,600 acute care hospitals in the United States.[6] The primary data used to calculate this score are collected through the Leapfrog Hospital Survey, the Agency for Healthcare Research and Quality, the Centers for Disease Control and Prevention, and the Centers for Medicare and Medicaid Services (CMS). The American Hospital Association's (AHA) Annual Survey is used as a secondary data source as necessary. The Leapfrog Group conducts the survey annually, and substantial efforts are put forth to invite hospital administrators to participate in the survey. Participation in the Leapfrog survey is optional and free of charge.

Leapfrog recently moved a step further in their evaluation of hospital safety by releasing the Hidden Surcharge Calculator to enable employers to estimate the hidden surcharge they pay for their employees and dependents because of hospital errors.[7] The calculation depends largely on the letter grade (AF) that the hospital received from Leapfrog's Hospital Safety Score. For example, Leapfrog estimated a commercially insured patient admitted to a hospital with a grade of C or lower would incur $1845 additional cost per admission than if the same patient was admitted to a hospital with a grade of A.[7] The Leapfrog group encourages employers and payers to use this information to adjust benefits structures so that employees are discouraged from using hospitals that receive lower hospital safety scores. Leapfrog also encourages payers to negotiate lower reimbursement rates for hospitals with lower hospital safety scores.

The accuracy of Leapfrog's hospital safety grades warrants attention because of the methodology used to score hospitals that do not participate in the Leapfrog Survey. One common barrier that prevents hospitals from participating is the amount of effort required to complete the annual survey, including extensive inputs from hospital executives and staff. According to Leapfrog, 4 to 6 days are required for a hospital to compile the necessary survey data.[8] Leapfrog estimates a 90‐minute commitment for the hospital chief executive officer or designated administrator to enter the information into the online questionnaire. This is a significant commitment for many hospitals. As a result, among the approximately 2600 acute care hospitals covered by Leapfrog's 2012 to 2013 safety grading, only 1100 (or 42.3%) actually participated in the Leapfrog hospital survey. This limits Leapfrog's ability to provide accurate scores and assign fair safety grades to many hospitals.

METHODS

RESULTS

Out of these 35 top hospitals, those that participated in the Leapfrog Survey generally received higher scores than the nonparticipants (Table 2). The group of participating hospitals received an average grade of A (mean safety score, 3.165; standard error of the mean [SE], 0.081), whereas the nonparticipating hospitals received an average grade of B (mean safety score, 3.012; SE, 0.047). These grades were consistent whether mean or median scores were used.

To further examine the potential bias against nonparticipating hospitals, the safety scores for each of the 17 nonparticipating hospitals were estimated as if they had participated in the Leapfrog Survey. The letter grade of this group increased from an average of B (mean safety score, 3.012; SE, 0.047) to an average of A (mean safety score, 3.216; SE, 0.046). Among the 17 nonparticipating hospitals, 15 showed an increase in safety score, of which 8 hospitals rescored a change in score significant enough to receive 1 or 2 letter grades higher (Table 3). Only 2 hospitals had slight decreases in safety score, without any impact on letter grade.

We applied the same methods to test the top 17 Honor Roll Hospitals as designated by US News & World Report; among them, half are participating hospitals and another half nonparticipating hospitals. One hospital, Johns Hopkins Hospital was not scored by Leapfrog because no relevant Medicare data are available for Leapfrog to calculate its safety score. For this reason, Johns Hopkins was excluded from our comparison. The results persist even with this smaller sample of top hospitals. The group of 8 participating hospitals had an average grade of A (mean safety score, 3.145; SE, 0.146), whereas another 8 nonparticipating hospitals received an average grade of B (mean safety score, 3.011; SE, 0.075).

DISCUSSION

The Leapfrog Group's intent to provide patient safety information to patients, physicians, healthcare purchasers, and hospital executives should be commended. However, the current methodology may disadvantage nonparticipating hospitals. The combination of lower maximum scores and increased weight of the CPOE and IPS scores may result in a lower hospital safety score than is justified. Nonparticipating hospitals may also face more intensive pressure from employers and payors to lower their reimbursement rates due to the newly released Leapfrog Hidden Surcharge Calculator.

Leapfrog acknowledges that the more data points a hospital has to be scored on, the better its opportunity to achieve a higher score.[8] This justification may lead to bias against nonparticipating hospitals. On the other hand, it is possible that hospitals with good safety records are more likely to participate in the Leapfrog Survey than those with poorer safety records. Without detailed nonresponse analysis from Leapfrog, it is impossible to know if there is a selection bias. Regardless, the Leapfrog result can subsequently misguide the payment rate negotiation between insurers and hospitals.

With this consideration in mind, Leapfrog should explicitly acknowledge the limitations of its methodology and consider revising it in future studies. For example, Leapfrog could only report on those measures for which there are data available for both participating and nonparticipating hospitals. Pending this revision, every effort must be made to distinguish between participating and nonparticipating hospitals. The outcomes of Leapfrog's hospital safety grades are made available online to consumers without distinguishing between participating and nonparticipating hospitals. The only method to differentiate the categories is to examine the data sources in detail amid a large volume of data. It is unlikely that consumers comparing hospital safety grades will take note of this caveat. Thus, Leapfrog's grading system can drastically misrepresent many nonparticipating hospitals' patient safety performances.

This study of The Leapfrog Group's Hospital Safety Score is not without limitations. The small sample utilized in this study limited the power of statistical testing. The difference in mean scores between participating and nonparticipating hospitals is not statistically significant. However, The Leapfrog Group uses specific numerical cutoff points for each letter grade classification. In this classification system statistical significance is not considered when assigning hospitals with different letter grades. It was clear that nonparticipating hospitals were more likely to receive lower letter grades than participating hospitals.

The small sample also posed challenges when attempting to account for missing data when comparing participating hospitals versus nonparticipating hospitals. Although a multiple imputation approach may have been ideal to address this, the small sample size coupled with the large amount of missing data (58% of hospitals did not participate in the Leapfrog Survey) led us to question the accuracy of this approach in this situation.[12] Instead, a crude, mean imputation approach was utilized, relying on the assumption that nonresponding hospitals had the same mean performance as responding hospitals on those domains where data were missing. In this study, we purposely selected a sample of hospitals from U.S. News & World Report's top hospitals. We believe the mean imputation approach, although not perfect, is appropriate for this sample of hospitals. Future study, however, should examine if hospitals that anticipated lower performance scores would be less likely to participate in the Leapfrog Survey. This would help strengthen Leapfrog's methodology in dealing with nonresponsive hospitals.

The Institute of Medicine (IOM) reported over a decade ago that between 44,000 and 98,000 deaths occurred every year due to preventable medical errors.[1] The report sparked an intense interest in identifying, measuring, and reporting hospital performance in patient safety.[2] The report also sparked the implementation of many initiatives aiming to improve patient safety.[3] Despite these efforts, there is still much room for improvement in the area of patient safety.[4] As the public has become more aware of patient safety issues, there has been an increased demand for information on hospital safety. The Leapfrog Group, a leading organization that examines and reports on hospital performance in patient safety, cites the IOM report as providing the focus that their newly formed organization required.[5]

Using 26 national measures of safety, The Leapfrog Group calculates a numeric Hospital Safety Score for over 2,600 acute care hospitals in the United States.[6] The primary data used to calculate this score are collected through the Leapfrog Hospital Survey, the Agency for Healthcare Research and Quality, the Centers for Disease Control and Prevention, and the Centers for Medicare and Medicaid Services (CMS). The American Hospital Association's (AHA) Annual Survey is used as a secondary data source as necessary. The Leapfrog Group conducts the survey annually, and substantial efforts are put forth to invite hospital administrators to participate in the survey. Participation in the Leapfrog survey is optional and free of charge.

Leapfrog recently moved a step further in their evaluation of hospital safety by releasing the Hidden Surcharge Calculator to enable employers to estimate the hidden surcharge they pay for their employees and dependents because of hospital errors.[7] The calculation depends largely on the letter grade (AF) that the hospital received from Leapfrog's Hospital Safety Score. For example, Leapfrog estimated a commercially insured patient admitted to a hospital with a grade of C or lower would incur $1845 additional cost per admission than if the same patient was admitted to a hospital with a grade of A.[7] The Leapfrog group encourages employers and payers to use this information to adjust benefits structures so that employees are discouraged from using hospitals that receive lower hospital safety scores. Leapfrog also encourages payers to negotiate lower reimbursement rates for hospitals with lower hospital safety scores.

The accuracy of Leapfrog's hospital safety grades warrants attention because of the methodology used to score hospitals that do not participate in the Leapfrog Survey. One common barrier that prevents hospitals from participating is the amount of effort required to complete the annual survey, including extensive inputs from hospital executives and staff. According to Leapfrog, 4 to 6 days are required for a hospital to compile the necessary survey data.[8] Leapfrog estimates a 90‐minute commitment for the hospital chief executive officer or designated administrator to enter the information into the online questionnaire. This is a significant commitment for many hospitals. As a result, among the approximately 2600 acute care hospitals covered by Leapfrog's 2012 to 2013 safety grading, only 1100 (or 42.3%) actually participated in the Leapfrog hospital survey. This limits Leapfrog's ability to provide accurate scores and assign fair safety grades to many hospitals.

METHODS

RESULTS

Out of these 35 top hospitals, those that participated in the Leapfrog Survey generally received higher scores than the nonparticipants (Table 2). The group of participating hospitals received an average grade of A (mean safety score, 3.165; standard error of the mean [SE], 0.081), whereas the nonparticipating hospitals received an average grade of B (mean safety score, 3.012; SE, 0.047). These grades were consistent whether mean or median scores were used.

To further examine the potential bias against nonparticipating hospitals, the safety scores for each of the 17 nonparticipating hospitals were estimated as if they had participated in the Leapfrog Survey. The letter grade of this group increased from an average of B (mean safety score, 3.012; SE, 0.047) to an average of A (mean safety score, 3.216; SE, 0.046). Among the 17 nonparticipating hospitals, 15 showed an increase in safety score, of which 8 hospitals rescored a change in score significant enough to receive 1 or 2 letter grades higher (Table 3). Only 2 hospitals had slight decreases in safety score, without any impact on letter grade.

We applied the same methods to test the top 17 Honor Roll Hospitals as designated by US News & World Report; among them, half are participating hospitals and another half nonparticipating hospitals. One hospital, Johns Hopkins Hospital was not scored by Leapfrog because no relevant Medicare data are available for Leapfrog to calculate its safety score. For this reason, Johns Hopkins was excluded from our comparison. The results persist even with this smaller sample of top hospitals. The group of 8 participating hospitals had an average grade of A (mean safety score, 3.145; SE, 0.146), whereas another 8 nonparticipating hospitals received an average grade of B (mean safety score, 3.011; SE, 0.075).

DISCUSSION

The Leapfrog Group's intent to provide patient safety information to patients, physicians, healthcare purchasers, and hospital executives should be commended. However, the current methodology may disadvantage nonparticipating hospitals. The combination of lower maximum scores and increased weight of the CPOE and IPS scores may result in a lower hospital safety score than is justified. Nonparticipating hospitals may also face more intensive pressure from employers and payors to lower their reimbursement rates due to the newly released Leapfrog Hidden Surcharge Calculator.

Leapfrog acknowledges that the more data points a hospital has to be scored on, the better its opportunity to achieve a higher score.[8] This justification may lead to bias against nonparticipating hospitals. On the other hand, it is possible that hospitals with good safety records are more likely to participate in the Leapfrog Survey than those with poorer safety records. Without detailed nonresponse analysis from Leapfrog, it is impossible to know if there is a selection bias. Regardless, the Leapfrog result can subsequently misguide the payment rate negotiation between insurers and hospitals.

With this consideration in mind, Leapfrog should explicitly acknowledge the limitations of its methodology and consider revising it in future studies. For example, Leapfrog could only report on those measures for which there are data available for both participating and nonparticipating hospitals. Pending this revision, every effort must be made to distinguish between participating and nonparticipating hospitals. The outcomes of Leapfrog's hospital safety grades are made available online to consumers without distinguishing between participating and nonparticipating hospitals. The only method to differentiate the categories is to examine the data sources in detail amid a large volume of data. It is unlikely that consumers comparing hospital safety grades will take note of this caveat. Thus, Leapfrog's grading system can drastically misrepresent many nonparticipating hospitals' patient safety performances.

This study of The Leapfrog Group's Hospital Safety Score is not without limitations. The small sample utilized in this study limited the power of statistical testing. The difference in mean scores between participating and nonparticipating hospitals is not statistically significant. However, The Leapfrog Group uses specific numerical cutoff points for each letter grade classification. In this classification system statistical significance is not considered when assigning hospitals with different letter grades. It was clear that nonparticipating hospitals were more likely to receive lower letter grades than participating hospitals.

The small sample also posed challenges when attempting to account for missing data when comparing participating hospitals versus nonparticipating hospitals. Although a multiple imputation approach may have been ideal to address this, the small sample size coupled with the large amount of missing data (58% of hospitals did not participate in the Leapfrog Survey) led us to question the accuracy of this approach in this situation.[12] Instead, a crude, mean imputation approach was utilized, relying on the assumption that nonresponding hospitals had the same mean performance as responding hospitals on those domains where data were missing. In this study, we purposely selected a sample of hospitals from U.S. News & World Report's top hospitals. We believe the mean imputation approach, although not perfect, is appropriate for this sample of hospitals. Future study, however, should examine if hospitals that anticipated lower performance scores would be less likely to participate in the Leapfrog Survey. This would help strengthen Leapfrog's methodology in dealing with nonresponsive hospitals.

The Institute of Medicine (IOM) reported over a decade ago that between 44,000 and 98,000 deaths occurred every year due to preventable medical errors.[1] The report sparked an intense interest in identifying, measuring, and reporting hospital performance in patient safety.[2] The report also sparked the implementation of many initiatives aiming to improve patient safety.[3] Despite these efforts, there is still much room for improvement in the area of patient safety.[4] As the public has become more aware of patient safety issues, there has been an increased demand for information on hospital safety. The Leapfrog Group, a leading organization that examines and reports on hospital performance in patient safety, cites the IOM report as providing the focus that their newly formed organization required.[5]

Using 26 national measures of safety, The Leapfrog Group calculates a numeric Hospital Safety Score for over 2,600 acute care hospitals in the United States.[6] The primary data used to calculate this score are collected through the Leapfrog Hospital Survey, the Agency for Healthcare Research and Quality, the Centers for Disease Control and Prevention, and the Centers for Medicare and Medicaid Services (CMS). The American Hospital Association's (AHA) Annual Survey is used as a secondary data source as necessary. The Leapfrog Group conducts the survey annually, and substantial efforts are put forth to invite hospital administrators to participate in the survey. Participation in the Leapfrog survey is optional and free of charge.

Leapfrog recently moved a step further in their evaluation of hospital safety by releasing the Hidden Surcharge Calculator to enable employers to estimate the hidden surcharge they pay for their employees and dependents because of hospital errors.[7] The calculation depends largely on the letter grade (AF) that the hospital received from Leapfrog's Hospital Safety Score. For example, Leapfrog estimated a commercially insured patient admitted to a hospital with a grade of C or lower would incur $1845 additional cost per admission than if the same patient was admitted to a hospital with a grade of A.[7] The Leapfrog group encourages employers and payers to use this information to adjust benefits structures so that employees are discouraged from using hospitals that receive lower hospital safety scores. Leapfrog also encourages payers to negotiate lower reimbursement rates for hospitals with lower hospital safety scores.

The accuracy of Leapfrog's hospital safety grades warrants attention because of the methodology used to score hospitals that do not participate in the Leapfrog Survey. One common barrier that prevents hospitals from participating is the amount of effort required to complete the annual survey, including extensive inputs from hospital executives and staff. According to Leapfrog, 4 to 6 days are required for a hospital to compile the necessary survey data.[8] Leapfrog estimates a 90‐minute commitment for the hospital chief executive officer or designated administrator to enter the information into the online questionnaire. This is a significant commitment for many hospitals. As a result, among the approximately 2600 acute care hospitals covered by Leapfrog's 2012 to 2013 safety grading, only 1100 (or 42.3%) actually participated in the Leapfrog hospital survey. This limits Leapfrog's ability to provide accurate scores and assign fair safety grades to many hospitals.

METHODS

RESULTS

Out of these 35 top hospitals, those that participated in the Leapfrog Survey generally received higher scores than the nonparticipants (Table 2). The group of participating hospitals received an average grade of A (mean safety score, 3.165; standard error of the mean [SE], 0.081), whereas the nonparticipating hospitals received an average grade of B (mean safety score, 3.012; SE, 0.047). These grades were consistent whether mean or median scores were used.

To further examine the potential bias against nonparticipating hospitals, the safety scores for each of the 17 nonparticipating hospitals were estimated as if they had participated in the Leapfrog Survey. The letter grade of this group increased from an average of B (mean safety score, 3.012; SE, 0.047) to an average of A (mean safety score, 3.216; SE, 0.046). Among the 17 nonparticipating hospitals, 15 showed an increase in safety score, of which 8 hospitals rescored a change in score significant enough to receive 1 or 2 letter grades higher (Table 3). Only 2 hospitals had slight decreases in safety score, without any impact on letter grade.

We applied the same methods to test the top 17 Honor Roll Hospitals as designated by US News & World Report; among them, half are participating hospitals and another half nonparticipating hospitals. One hospital, Johns Hopkins Hospital was not scored by Leapfrog because no relevant Medicare data are available for Leapfrog to calculate its safety score. For this reason, Johns Hopkins was excluded from our comparison. The results persist even with this smaller sample of top hospitals. The group of 8 participating hospitals had an average grade of A (mean safety score, 3.145; SE, 0.146), whereas another 8 nonparticipating hospitals received an average grade of B (mean safety score, 3.011; SE, 0.075).

DISCUSSION

The Leapfrog Group's intent to provide patient safety information to patients, physicians, healthcare purchasers, and hospital executives should be commended. However, the current methodology may disadvantage nonparticipating hospitals. The combination of lower maximum scores and increased weight of the CPOE and IPS scores may result in a lower hospital safety score than is justified. Nonparticipating hospitals may also face more intensive pressure from employers and payors to lower their reimbursement rates due to the newly released Leapfrog Hidden Surcharge Calculator.

Leapfrog acknowledges that the more data points a hospital has to be scored on, the better its opportunity to achieve a higher score.[8] This justification may lead to bias against nonparticipating hospitals. On the other hand, it is possible that hospitals with good safety records are more likely to participate in the Leapfrog Survey than those with poorer safety records. Without detailed nonresponse analysis from Leapfrog, it is impossible to know if there is a selection bias. Regardless, the Leapfrog result can subsequently misguide the payment rate negotiation between insurers and hospitals.

With this consideration in mind, Leapfrog should explicitly acknowledge the limitations of its methodology and consider revising it in future studies. For example, Leapfrog could only report on those measures for which there are data available for both participating and nonparticipating hospitals. Pending this revision, every effort must be made to distinguish between participating and nonparticipating hospitals. The outcomes of Leapfrog's hospital safety grades are made available online to consumers without distinguishing between participating and nonparticipating hospitals. The only method to differentiate the categories is to examine the data sources in detail amid a large volume of data. It is unlikely that consumers comparing hospital safety grades will take note of this caveat. Thus, Leapfrog's grading system can drastically misrepresent many nonparticipating hospitals' patient safety performances.

This study of The Leapfrog Group's Hospital Safety Score is not without limitations. The small sample utilized in this study limited the power of statistical testing. The difference in mean scores between participating and nonparticipating hospitals is not statistically significant. However, The Leapfrog Group uses specific numerical cutoff points for each letter grade classification. In this classification system statistical significance is not considered when assigning hospitals with different letter grades. It was clear that nonparticipating hospitals were more likely to receive lower letter grades than participating hospitals.

The small sample also posed challenges when attempting to account for missing data when comparing participating hospitals versus nonparticipating hospitals. Although a multiple imputation approach may have been ideal to address this, the small sample size coupled with the large amount of missing data (58% of hospitals did not participate in the Leapfrog Survey) led us to question the accuracy of this approach in this situation.[12] Instead, a crude, mean imputation approach was utilized, relying on the assumption that nonresponding hospitals had the same mean performance as responding hospitals on those domains where data were missing. In this study, we purposely selected a sample of hospitals from U.S. News & World Report's top hospitals. We believe the mean imputation approach, although not perfect, is appropriate for this sample of hospitals. Future study, however, should examine if hospitals that anticipated lower performance scores would be less likely to participate in the Leapfrog Survey. This would help strengthen Leapfrog's methodology in dealing with nonresponsive hospitals.