Measuring outcomes of hospital care using multiple risk-adjusted indexes.

Using existing data sources, we developed three risk-adjusted measures of hospital quality: the risk-adjusted mortality index (RAMI), the risk-adjusted readmissions index (RARI), and the risk-adjusted complication index (RACI). We describe the construction and validation of each of these indexes. After these measures were developed, we tested the relationships among the three indexes using a sample of 300 hospitals. Actual numbers of adverse events were observed for each hospital and compared to the number predicted by the RAMI, RARI, and RACI models. Then each hospital was ranked on each index. Our results showed that no relationship existed between a hospital's ranking on any one of these indexes and its ranking on the other two indexes. This result provides some evidence that no measure of quality should be used by itself to represent different aspects of the quality of hospital care. Adequate overall measures of hospital quality will need to include multiple measures in order to be credible and to reflect the complexity of hospital care. The findings suggest that consumers, payers, and policymakers cannot simply choose one hospitalwide measure, such as the mortality rate, to validly represent a hospital's performance: those hospitals with high rankings on their mortality rates do not necessarily rank high on their readmission rates or complication rates.