Developing risk-adjusted 30-day hospital mortality rates.

This article describes one risk-adjustment method useful for minimizing threats to internal validity that stem from the impact on the outcomes under investigation from patients' own characteristics and their associated risks. Mortality is the outcome used to illustrate the risk-adjustment approach. A two-step approach to outcomes research is suggested. The first step includes risk-adjusting outcomes for patient characteristics by developing standard mortality rates. In the second step these risk-adjusted standard rates can be used as dependent variables in outcomes analytic models. This article focuses on the first step. In the current study risk adjustment resulted in changes in both absolute values and rank ordering of hospital mortality rates compared to crude rates. This procedure is useful for developing risk-adjusted outcomes with administrative data similar to those used in this study.