WOULD ELIMINATING DIFFERENCES IN PHYSICIAN PRACTICE STYLE REDUCE GEOGRAPHIC VARIATIONS IN CATARACT-SURGERY RATES

This study uses Medicare physician-claims data to examine patient and physician contributions to variations in cataract surgery rates across U.S. metropolitan areas. Utilization is modelled as having two phases : the decision to seek an ophthalmologist's care, which is made by pat ients, and the decision to perform surgery on patients who seek care, which is partially controlled by ophthalmologists. Under this model, t he effect of physician practice style on cataract surgery rates occurs through the influence of practice style on the second phase of utiliz ation. Variation in patient care-seeking behavior contributed to the v ariation in the rate of cataract surgery. Moreover, multivariate regre ssion analyses found that cataract surgery rates were influenced by ec onomic and sociodemographic variables in predictable ways. Using the r egression results, a ''purged'' cataract surgery rate that was free of any possible influence of physician practice style was calculated. Va riation in the purged surgery rate was only slightly lower than variat ion in the observed surgery rate, suggesting that eliminating practice style as a factor in physician decision making (e.g., through practic e guidelines) would reduce variations in cataract surgery rates by onl y a small amount.