CASEMIX ADJUSTMENT OF MANAGED CARE CLAIMS DATA USING THE CLINICAL CLASSIFICATION FOR HEALTH-POLICY RESEARCH METHOD

OBJECTIVES. The objective of this study was to explore the use of the Clinical Classification for Health Policy Research (CCHPR) as a casemi x adjustment method for examining physician practice patterns. METHODS . The data source was 2 years of administrative claims from an 86,000 member health maintenance organization in southeastern Michigan. The C CHPR version 2 algorithm, which is in the public domain, was used to a ssign each claim to one of 260 clinical categories. CCHPR and age-sex categories were used as explanatory variables in multiple linear regre ssion models with approved claims payments in dollars as the outcome v ariable. Regressions were performed retrospectively for 1994 and 1995, and with 1994 claims' history to predict 1995 utilization. Similar re gressions were performed with age-sex categories alone, and also with the ambulatory diagnostic groups. RESULTS. The adjusted R-2 value of t he retrospective regression models fur total approved dollars was 0.42 for both study years when CCHPR categories were used. In contrast, ag e-sex explanatory variables alone achieved an R-2 of 0,02.CONCLUSIONS. The CCHPR method appears to be a promising tool to understand variabi lity in physician resource utilization in managed care.