Comparing classification methods: measurement of variations in charges, length of stay, and mortality.

We define and examine three alternative systems for categorizing hospital patients. The first system is based on discharge abstract data alone; the second system is based on discharge abstract data that has been reabstracted from charts for completeness and accuracy; the third system is based on a severity-of-illness index within a diagnostic group. Using acute myocardial infarction patients as an illustrative example, we examine the homogeneity of these categorization systems with respect to charges, length of stay and mortality rates. Our results indicate that a measure of patient severity of illness is essential to produce homogeneous categories to study hospital productivity for utilization review assessment by PSROs, for planning purposes by Health Systems Agencies, for hospital rate setting by cost review commissions and for internal hospital financial management and utilization review studies.