Low-Mortality Hospitals

The primary independent variable was in-hospital mortality rank. We used observed-to-expected mortality ratios to benchmark hospitals based on in-hospital mortality for patients included in the cohort. To do this, we performed multivariable logistic regression analysis with in-hospital mortality as the outcome to predict the individual probability of mortality for each patient. Covariates included age, sex, race/ethnicity, CCI category, ISS, and head AIS score. The derived probability of in-hospital mortality for each patient in the cohort was summed for each hospital to determine the expected number of deaths. The observed in-hospital mortality was the number of deaths that occurred among patients at each hospital. Hospitals were then ranked into quartiles based on observed-to-expected ratios, and those in the lowest quartile were designated low-mortality hospitals. Patients at all other hospitals composed the comparison group.