Primary care physician volume and quality of diabetes care: a population-based cohort study

Background — A relationship between larger patient volume and both better quality of care and better outcomes has been shown for many acute care conditions. It is uncertain whether a volume–quality relationship exists for the outpatient management of chronic diseases.

Objective — To explore the association between primary care physician volume and the quality of diabetes care.

Design — Cohort study.

Setting — The study was conducted using linked population-based healthcare administrative data in Ontario, Canada.

Patients — All 1,018,647 adults with diabetes in 2011 who received care from 9,014 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 six indicators: disease monitoring (eye examination, A1c testing, LDL-cholesterol testing), prescription of appropriate medications (angiotensin-converting-enzyme inhibitors/angiotensin-receptor blockers, statins), and adverse clinical outcomes (emergency department visits for hypo- 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 six indicators. 

Limitations — Only a select set of quality indicators and potential confounders could be ascertained from available data.

Conclusions — Primary care physicians with busier ambulatory patient practices delivered lower quality of diabetes care, but those with greater diabetes-specific experience delivered better quality of 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 low diabetes volumes may improve care.