Association between physician supply, local practice norms, and outpatient visit rates.

Background: There is considerable regional variation in Medicare outpatient visit rates; such variations may be the consequence of patient health, race/ethnicity differences, patient preferences, or physician supply and beliefs about the efficacy of frequently scheduled visits.

Objective: The objective of the study was to test associations between varying regional Medicare outpatient visit rates and beneficiaries' health, race/ethnicity, preferences, and physician practice norms and supply.

Methods: We used Medicare claims from 2006 and 2007 and data from national surveys of 3 different groups in 2005-Medicare beneficiaries, cardiologists, and primary care physicians. Regression analysis tested explanations for outpatient visit rates: patient health (self-reported and hierarchical condition category score), self-reported race/ethnicity, preferences for care, and local physician practice norms and supply in beneficiaries' Hospital Referral Regions (HRRs) of residence.

Results: Beneficiaries in the highest quintile of the hierarchical condition category scores experienced 4.99 more visits than those in the lowest. Beneficiaries who were black experienced 2.14 fewer visits than others with similar health and preferences. Higher care-seeking preferences were marginally significantly associated with more visits, whereas education and poverty were insignificant. HRRs with high physician supply and high-frequency practice norms were associated with 2.04 additional visits per year, whereas HRRs with high supply but low-frequency norms were associated with 1.45 additional visits. Adjusting for all individual beneficiary covariates explained <20% of the original associations between visit rates and physician supply and practice norms.

Conclusions: Medicare beneficiaries' health status, race, and preferences help explain individual office visit frequency; in particular, African-American patients appear to experience lower access to care. Yet, these factors explain a small fraction of the observed regional differences associated with physician supply and beliefs about the appropriate frequency of office visits.