Basu S, et al. - In this epidemiological study of US population data, researchers identified changes in the supply of primary care physicians in US counties between 2005 and 2015 and the connection between these changes and population mortality. Between 2005 and 2015, supply of primary care physicians per capita decreased. Findings suggested an link between greater primary care physician supply with lower mortality, so programs to direct more resources to primary care physician supply could be important for overall population health.

Methods

• This investigation assessed 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.
• To examine 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, data from 3,142 US counties, 7,144 primary care service areas and 306 hospital referral regions were used.
• From March to July 2018, analysis was performed; main outcomes and measures included age-standardized life expectancy, cause-specific mortality, and restricted mean survival time.

Results

• Investigators found that primary care physician supply increased from 196,014 physicians in 2005 to 204,419 in 2015.
• Due to disproportionate losses of primary care physicians in some counties and an increase in population, the mean (SD) density of primary care physicians relative to population size was reduced 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); there were higher losses in rural areas.
• In adjusted mixed-effects regressions, every 10 additional primary care physicians per 100,000 population was linked to a 51.5-day increase in life expectancy (95% CI, 29.5-73.5 days; 0.2% increase); 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 reduction of cardiovascular, cancer and respiratory mortality by 0.9% to 1.4% was linked to a total of 10 additional primary care physicians per 100,000 population; analyses at different geographic levels, utilizing instrumental variable regressions, or at the individual level found comparable benefits related to primary care supply.