Measuring severity of illness: comparisons across institutions.

Conventional methods for classifying patients with respect to utilization of health care resources are based almost exclusively on diagnostic criteria. We review a new severity of illness index which is generic to most medical and surgical conditions in a hospital, and which has been found to produce subgroups of patients more homogeneous with respect to hospital resource use (as assessed by total charges, length of stay, routine charges, and laboratory charges) than diagnostic-related groups, staging, and generalized patient management paths. We use the severity of illness groups to compare total charges and length of stay across hospitals. We find that charges and length of stay in an academic teaching hospital are similar to those in community hospitals with and without teaching programs when controlling for severity of illness. (Am J Public Health 1983; 73:25-31.)