Limits of readmission rates in measuring hospital quality suggest the need for added metrics.

Recent national policies use risk-standardized readmission rates to measure hospital performance on the theory that readmissions reflect dimensions of the quality of patient care that are influenced by hospitals. In this article our objective was to assess readmission rates as a hospital quality measure. First we compared quartile rankings of hospitals based on readmission rates in 2009 and 2011 to see whether hospitals maintained their relative performance or whether shifts occurred that suggested either changes in quality or random variation. Next we examined the relationship between readmission rates and several commonly used hospital quality indicators, including risk-standardized mortality rates, volume, teaching status, and process-measure performance. We found that quartile rankings fluctuated and that readmission rates for lower-performing hospitals in 2009 tended to improve by 2011, while readmission rates for higher-performing hospitals tended to worsen. Regression to the mean (a form of statistical noise) accounted for a portion of the changes in hospital performance. We also found that readmission rates were higher in teaching hospitals and were weakly correlated with the other indicators of hospital quality. Policy makers should consider augmenting the use of readmission rates with other measures of hospital performance during care transitions and should build on current efforts that take a communitywide approach to the readmissions issue.