Primary Care Physician Volume and Quality of Diabetes Care: A Population-Based Cohort Study.

BACKGROUND: A relationship between higher patient volume and both better quality of care and better outcomes has been shown for many acute care conditions. Whether a volume-quality relationship exists for the outpatient management of chronic diseases is uncertain. OBJECTIVE: To explore the association between primary care physician volume and quality of diabetes care. DESIGN: Cohort study. SETTING: The study was conducted using linked population-based health care administrative data in Ontario, Canada. PATIENTS: 1 018 647 adults with diabetes in 2011 who received care from 9014 primary care physicians. Two measures of volume were ascertained for each physician: overall ambulatory volume (representing time available to devote to chronic disease management during patient encounters) and diabetes-specific volume (representing disease-specific expertise). MEASUREMENTS: Quality of care was measured over a 2-year period using 6 indicators: disease monitoring (eye examination, hemoglobin A1c testing, and low-density lipoprotein cholesterol testing), prescribing appropriate medications (angiotensin-converting enzyme inhibitors or angiotensin-receptor blockers and statins), and adverse clinical outcomes (emergency department visits for hypoglycemia or hyperglycemia). RESULTS: Higher overall ambulatory volume was associated with lower rates of appropriate disease monitoring and medication prescription. In contrast, higher diabetes-specific volume was associated with better quality of care across all 6 indicators. LIMITATION: Only a select set of quality indicators and potential confounders could be ascertained from available data. CONCLUSION: Primary care physicians with busier ambulatory patient practices delivered lower-quality diabetes care, but those with greater diabetes-specific experience delivered higher-quality care. These findings show that relationships between physician volume and quality can be extended from acute care to outpatient chronic disease care. Health policies or programs to support physicians with a low volume of patients with diabetes may improve care. PRIMARY FUNDING SOURCE: Canadian Institutes of Health Research.