Profiling primary care physician resource use: examining the application of case mix adjustment

Growing emphasis on managed care has led to increased interest in physician practice profiling. Standardized techniques for conducting profiling are not yet well established. One particularly challenging methodologic issue, case mix adjustment, is explored here using actual cost profiles derived from primary care physicians at two independent practice association (IPA)-model health maintenance organizations (HMOs). Specifically, this article examines how the ambulatory care group case mix methodology can be applied to profiling and illustrates that it provides more depth of information with which to assess performance than does standard demographic adjustment alone. This analysis suggests both the potential and methodologic limitations of profiling at the individual physician level.