Case mix in HMOs and fee-for-service systems: The ratio of routine visits to total visits in adult primary care

Abstract

To estimate differences between HMOs and fee-for-service systems with respect to one aspect of case mix in adult primary care, data from a Kaiser-Permanente Medical Care Program (K-P) were compared with data from the National Ambulatory Medical Care Survey (NAMCS). The ratio of routine office visits to total office visits appears to be five percentage points higher for K-P. The figure there is 83%, as opposed to 78% for NAMCS. The differential appears to reflect differences in patient and system characteristics, with possible implications for national policy.