Primary Care Physician Workforce and Patient Outcomes

Most scenarios to improve the outcomes and efficiency of the healthcare system in the United States include strengthening the role of primary care. Due to a decreasing interest in primary care among graduates of US medical schools, there are projections of a future shortage of general internists and family physicians to care for a growing number of elderly patients. Some studies have found an association between a greater number of primary care physicians per population and improved health outcomes. However, other studies have observed mixed associations, and the associations seen in studies of ambulatory care sensitive condition (ACSC) hospitalizations and spending have been inconsistent. The earlier studies have utilized the American Medical Association (AMA) Masterfile to measure the number of primary care physicians, a source that, according to researchers, may not accurately reflect the proportion of primary care trained physicians providing ambulatory primary care. The researchers recently conducted a study using the AMA Masterfile as well as a new measure of the ambulatory primary care workforce derived from Medicare claims to test the hypotheses that high levels of the primary care physician workforce are associated with lower mortality, fewer ACSC hospitalizations, and lower spending in Medicare beneficiaries. Study results were reported in the Journal of the American Medical Association [2011;305(20):2096-2105]. The researchers conducted a cross-sectional analysis of the outcomes of a 2007 20% sample of fee-for-service Medicare beneficiaries ≥65 years of age (n=5,132,936). Inclusion criteria included age 65 to 99 years on January 1, 2007, and 2007 Part A and Part B coverage. The primary outcome measures were annual individual-level outcomes (mortality, ACSC hospitalizations, and Medicare program spending), adjusted for individual patient characteristics and geographic area variables. Based on zip codes, the researchers assigned a primary care service area (PCSA) to each study beneficiary. The analysis included 6542 PCSAs defined by aggregating zip code areas to form primary care market areas based on travel of Medicare beneficiaries to primary care physicians, advanced nurse practitioners, and physician assistants for ambulatory primary care. There was marked variation observed in the primary care physician workforce across areas, but low correlation between the 2 primary care workforce measures (P<.001). Beneficiaries in areas with the highest quintile of primary care physician measure using the AMA Masterfile counts had 6% lower rates of ACSC hospitalizations than those in areas with the lowest quintile (relative rate [RR], 0.94; 95% confidence interval [CI], 0.93-0.95) with adjusted rates of 74.90 (95% CI, 73.57-76.27) versus 79.61 (95% CI, 78.28-80.96) per 1000 beneficiaries, respectively. In models utilizing primary care physician full-time equivalents (FTEs) as the measure of primary care workforce, there were stronger associations observed. Not only did beneficiaries residing in the area with the highest quintile of primary care FTEs have 5% lower mortality (5.19 vs 5.49 per 100 beneficiaries; RR, 0.95; 95% CI, 0.93-0.96) but also 9% fewer ACSC hospitalizations (72.53 vs 79.48 per 1000 beneficiaries; RR, 0.91; 95% CI, 0.90-0.92) and 1% higher total Medicare program spending ($8857 vs $8769 per beneficiary; RR, 1.01; 95% CI, 1.004-1.02) compared with those in the area with the lowest quintile of primary care FTEs. The researchers summarized by saying, “a higher level of primary care physician workforce, particularly with an FTE measure that may more accurately reflect ambulatory primary care, was generally associated with favorable patient outcomes.” They added that “if all areas were assumed to have the same outcomes as the highest quintile of primary care physicians per population and all underlying assumptions were satisfied for 100% fee-for-service Medicare beneficiaries, there would be an estimated 670 fewer deaths, 159,144 fewer ACSC hospitalizations, and $4.4 billion more in total Medicare programs spending. Similarly, if all areas’ primary care FTEs increased to the highest quintile, the model suggests that this might lead to 48,398 fewer deaths and 436,002 fewer ACSC hospitalizations, but would cost $13.8 billion more in total Medicare spending. The higher spending is from more spending in clinician spending (Part B, $36.4 million more) that is more than the reduction from lower spending in acute care facilities (Part A, $22.6 million less).”