Association of Primary Care Physician Supply with Population Mortality in the United States, 2005-2015

Sanjay Basu, Seth A Berkowitz, Robert L Phillips, Asaf Bitton, Bruce E Landon, Russell S Phillips


Importance: Recent US health care reforms incentivize improved population health outcomes and primary care functions. It remains unclear how much improving primary care physician supply can improve population health, independent of other health care and socioeconomic factors.

Objectives: To identify primary care physician supply changes across US counties from 2005-2015 and associations between such changes and population mortality.

Design, setting, and participants: This epidemiological study evaluated US population data and individual-level claims data linked to mortality from 2005 to 2015 against changes in primary care and specialist physician supply from 2005 to 2015. Data from 3142 US counties, 7144 primary care service areas, and 306 hospital referral regions were used to investigate the association of primary care physician supply with changes in life expectancy and cause-specific mortality after adjustment for health care, demographic, socioeconomic, and behavioral covariates. Analysis was performed from March to July 2018.

Main outcomes and measures: Age-standardized life expectancy, cause-specific mortality, and restricted mean survival time.

Results: Primary care physician supply increased from 196 014 physicians in 2005 to 204 419 in 2015. Owing to disproportionate losses of primary care physicians in some counties and population increases, the mean (SD) density of primary care physicians relative to population size decreased from 46.6 per 100 000 population (95% CI, 0.0-114.6 per 100 000 population) to 41.4 per 100 000 population (95% CI, 0.0-108.6 per 100 000 population), with greater losses in rural areas. In adjusted mixed-effects regressions, every 10 additional primary care physicians per 100 000 population was associated with a 51.5-day increase in life expectancy (95% CI, 29.5-73.5 days; 0.2% increase), whereas an increase in 10 specialist physicians per 100 000 population corresponded to a 19.2-day increase (95% CI, 7.0-31.3 days). A total of 10 additional primary care physicians per 100 000 population was associated with reduced cardiovascular, cancer, and respiratory mortality by 0.9% to 1.4%. Analyses at different geographic levels, using instrumental variable regressions, or at the individual level found similar benefits associated with primary care supply.

Conclusions and relevance: Greater primary care physician supply was associated with lower mortality, but per capita supply decreased between 2005 and 2015. Programs to explicitly direct more resources to primary care physician supply may be important for population health.

This article was featured on the July 22, 2021, Lunch and Learn discussion

In this segment of the recording of the July 22, 2021, online Lunch and Learn discussion, one of the authors of this paper, Dr. Sanjay Basu, Director of Research at the Harvard Center for Primary Care, presented the paper.


Policy Discussion Highlights from the Discussion:

  • Finance whole-person care:
    • Do not pay only for utilization but pay for wraparound services through a chronic-care model.
    • Pay for outcomes on a risk-adjusted basis where the risk calculator is invisible to the clinician.
  • Strengthen the medical education pipeline:
    • Medical schools are graduating fewer primary care clinicians.
    • Identify medical education, residency and post-residency incentives that improve the rate of primary care specialization among students.
  • Expand team-based care:
    • Utilize the full range of the primary care workforce including mobile pharmacists, mobile health workers, social workers, and so on, allowing each profession to work at the top of their license.
    • Conduct more research on the range of services provided in practices that include NPs and PAs.
  • Integrate behavioral health and primary care:
    • When practices provide a broader range of services (including counseling), their Medicare beneficiaries subsequently experience fewer ED visits and lower total spending.
    • Include team members who have behavioral health skills and take advantage of existing primary care physician competencies.
      • E.g., family medicine has historically included training in basic mental health counseling and cognitive behavioral therapy.
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