Relationship of physician volume with process measures and outcomes in diabetes.

Objective: The volume of patients cared for by an individual physician (physician volume) has been linked to improved outcomes for a number of conditions. It is not known whether a similar association exists for treatment of diabetes. In this study we aimed to determine whether physician volume is associated with improved process measures and outcomes in diabetes care.
Research Design and Methods: This retrospective cohort study analyzed electronic medical records data for 7,120 patients with diabetes treated by 368 primary care physicians at practices affiliated with two large academic hospitals. The associations between physician volume of diabetic patients (diabetes volume) and annual A1C and LDL testing, as well as blood pressure, A1C, and LDL levels, were evaluated.
Results: In multivariable analysis, absolute diabetes volume was linked to decreased odds of A1C testing (4% less for each additional patient seen; P = 0.05), and relative diabetes volume (fraction of the total patients seen who had diabetes) was associated with decreased odds of both A1C (25% less for every 10% increase in the number of diabetic patients seen annually; P = 0.03) and LDL testing (20% less for every 10% increase in the number of diabetic patients; P < 0.001). Physician volume was not significantly associated with the odds of blood pressure, A1C, or LDL control at the end of the study.
Conclusions: Higher physician volume in care of diabetic patients is associated with decreased adherence to surveillance guidelines and no measurable difference in treatment outcomes.