Primary care physician panel size and quality of care: a population-based study in Ontario, Canada

Purpose — To determine the relationship between the number of patients under a family physician’s care (panel size) and primary care quality indicators.

Methods — We conducted a cross-sectional population-based study of fee-for-service and capitated interprofessional and non interprofessional primary healthcare practices in Ontario (Canada) between April, 2008 and March, 2010, encompassing 4,195 family physicians with panel sizes ≥ 1200 serving 8.3 million patients. Data was extracted from multiple linked health-related administrative databases and covered 17 quality indicators: access, continuity, comprehensiveness, and evidence-based indicators of cancer screening and chronic disease management.

Results — The likelihood of being up-to-date on cervical, colorectal, and breast cancer screening showed a relative decrease of 8.8% (p<0.001), 6.2% (p=0.014), and 5.1% (p<0.001), respectively, with increasing panel size (from 1,200 to 4,000). Eight chronic care indicators (four medication-based and four screening-based) showed no significant association with panel size. However, the likelihood of individuals with a new diagnosis of congestive heart failure having an echocardiogram increased by a relative 9.1% (p<0.001) with higher panel size. Increasing panel size was also associated with a 10.5% relative increase in hospitalization rates for ambulatory care-sensitive conditions (p=0.044) and a 12.0% decrease in non-urgent emergency room visits (p=0.004). Continuity was highest with medium panel sizes (<0.001), and comprehensiveness had a small decrease (p=0.030) with increasing panel size.

Conclusions — Increasing panel size was associated with small decreases in cancer screening, continuity and comprehensiveness, but showed no consistent relationships with chronic disease management or access indicators. We found no panel size threshold above which quality of care suffered.

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