Research Evidence on the Validity of Risk-Adjusted Mortality Rate as a Measure of Hospital Quality of Care

For more than 10 years, reports comparing quality of care in hospitals have been disseminated to the public. The most commonly used measure in these reports is hospital mortality rate. Despite the resources devoted to analyzing and disseminating mortality data, little attention has been given to the question of their validity as a quality measure. In this article, the authors synthesize findings from 18 articles identified as providing information relevant to this issue. From this review, the authors find evidence that poor quality care increases patients' risk of mortality and that, on average, quality of care provided in hospitals identified as high—mortality rate outliers is poorer than that provided in low—mortality rate outlier hospitals. Nevertheless, a clear conclusion from these studies is that when used as a measure of quality for individual hospitals, risk-adjusted mortality rates are seriously inaccurate. Publication of hospital mortality rates misinforms the public about hospital quality.