The effects of patient volume on the quality of diabetic care for medicare beneficiaries

Background: The quality of care for Medicare beneficiaries with diabetes remains suboptimal. The contributing factors at the physician level are not well characterized, especially the relationship of patient volume and physician performance. Objective: We sought to determine associations between the number of Medicare diabetic patients cared for by a primary care physician and the receipt of important diabetic processes of care. Design: Physicians were grouped into quintiles based on the number of Medicare patients with diabetes. Hierarchical generalized linear models were used to examine associations between number of patients, frequency of visits, physician experience, patient factors and the receipt of diabetes processes of care using Part A and B Medicare claims data for 2001. Participants and Patients: All Connecticut primary care physicians who cared for Medicare fee-for-service beneficiaries with diabetes in 2001. Main Outcome Measures: The main outcome measures were associations of the receipt of diabetes process of care measures with the number of diabetic Medicare patients in a physician practice panel, adjusted for frequency of visits, patient comorbidity, age, ethnicity, and physician experience. Results: Patients in the highest volume physician quintile were significantly more likely to have received hemoglobin A1c measurements, lipid profiles, and retinal eye examinations than patients in the lowest physician quintile in 2001, even after adjustment for multiple factors. For each step up in quintile volume group among primary care physicians, the increased odds of receiving a hemoglobin A1c measurement was 1.16 (95% confidence interval [CI] 1.10-1.23), 1.12 (95% CI 1.07-1.18) for a lipid profile, 1.06 (95% CI 1.02-1.09) for a retinal eye examination, and 1.48 (95% CI 1.22-1.81) for receiving all 3 measures. Conclusions: This study suggests that Medicare fee-for-service patients with diabetes cared for by physicians with greater numbers of diabetic Medicare patients in their practice are more likely to receive important diabetes processes of care.