Physician supply, treatment, and amputation rates for peripheral arterial disease

Objective: To test whether the availability of vascular surgeons and interventional radiologists in a region affects revascularization and amputation rates for patients with peripheral arterial disease (PAD). Methods: We identified all patients with PAD in the Medicare claims database in 1994 and tracked their claims through 1999. We aggregated risk-adjusted data on the 143,202 patients who survived through 1999 by Hospital Referral Region and merged this data with information on local physician supply and other regional characteristics. Instrumental variables analysis was used to account for unobserved illness severity. Main outcome measures were risk-adjusted rates of lower extremity bypass surgery, angioplasty, and amputation by region. Results: Increasing vascular surgeon supply in a region by approximately one standard deviation (.30/10,000 Medicare beneficiaries) is associated with a 0.9 percentage point increase in bypass surgery rates and a 1.6 percentage point reduction in amputation rates. We find weaker evidence that greater availability of interventional radiologists increases angioplasty rates and reduces amputation rates. Factors reflecting regional attractiveness, such as the rating of a region based on climate, recreation, crime, and other attributes, were strong independent predictors of the number of vascular surgeons and interventional radiologists in an area. Conclusions: Availability of specialists affects outcomes for PAD patients. Regional variability in specialists who treat PAD is influenced by factors other than regional medical needs. Policies aimed at increasing the supply of vascular surgeons and interventional radiologists and their provision of bypass surgery in underserved areas may help to reduce regional disparities in amputation