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The supply of primary care provided by internal medicine subspecialists.


Vandergrift J, Gray B, Lipner RS. — American Board of Internal Medicine

Presented: AcademyHealth Annual Research Meeting, June 2014

Objective: Current projections suggest the United States will experience a primary care physician (PCP) shortage. Yet, there are no recent studies identifying the degree to which subspecialists provide primary care (PC) services or how subspecialist PC delivery responds to shortages. This study addressed this trend by examining the degree to which internal medicine (IM) subspecialists extend generalist capacity by providing principal PC services (i.e., ongoing patient care for specific conditions) as well as other general PC (i.e., PC services other than ongoing management of specific conditions), and the extent to which their principal and general PC delivery is driven by PCP shortages.

Study Design: When physicians enroll in American Board of internal Medicine's Maintenance of Certification (MOC) program, all physicians complete a practice characteristics survey in which they delineate their clinical time in principal PC, general PC, and other types of care as well as their practice location. These survey data were obtained from 18,249 mid-career subspecialists who registered for MOC between 2006 and 2013. County-level measures of PCP supply, urbanicity, IM subspecialist supply, and socioeconomic status from the Area Health Resource File and Census were applied. A two-part model (logistic and log-binomial regression) was used to examine how differences in PCP supply between counties were associated with time in PC for IM subspecialists. The provision of these services responded to changes in PCP density over time and was examined by utilizing a panel regression with county fixed effects and accounting for correlated errors.

Population Studied: Clinically active mid-career IM subspecialists (median of 10 years post-fellowship).

Principal Findings: On average, subspecialists reported 31% of clinical time delivering PC services; more so as principal PC (mean=22%) versus general PC (mean=8%). Their remaining time was mostly in consultative (mean=39%) or hospital/procedural care (mean=30%). Principal PC time ranged from 2% among intensivists to 46% among oncologists. Geriatricians (60%), infectious disease specialists (13%), and pulmonologists (12%) reported the most general PC. In the cross-sectional analysis, a decrease in one PCP per 10,000 people between counties (mean=6.4) was associated with a 0.4 percentage point (pp) increase in general PC delivery (p=0.003), but was unrelated to principal PC delivery (p=0.08). Differences in the effect of PCP density on principal (p<0.001) and general (p<0.001) PC delivery were observed across subspecialties. For general PC, geriatricians (1.5 pp, p=0.02) reported the largest effect of PCP density. Only cardiologists (0.6 pp, p=0.007) demonstrated a significant increase in principal PC. Changes in PCP density within counties between 2005 and 2011 (13% decrease or 0.9 PCPs per 10,000 people) were unrelated to principal (p=0.29) or general (p=0.56) PC delivery.

Conclusion: IM subspecialists deliver substantial PC services, mostly as principal care, with wide variation across subspecialties. Few responses to changes in PCP density over time or across counties were observed.

Implications for Policy or Practice: Concerning PCP shortages, policy makers charged with regulating fellowship slots should consider that certain IM subspecialties provide significant PC services. However, little evidence was found to suggest subspecialists will respond to PCP shortages by supplying more PC without additional incentives.

For more information about this presentation, please contact Research@abim.org.