title: Primary care physician workforce and Medicare beneficiaries' health outcomes.
abstract: BACKGROUND
  Despite a widespread interest in increasing the numbers of primary care physicians to improve care and to moderate costs, the relationship of the primary care physician workforce to patient-level outcomes remains poorly understood.
  
  
  OBJECTIVE
  To measure the association between the adult primary care physician workforce and individual patient outcomes.
  
  
  METHODS
  A cross-sectional analysis of the outcomes of a 2007 20% sample of fee-for-service Medicare beneficiaries aged 65 years or older (N = 5,132,936), which used 2 measures of adult primary care physicians (general internists and family physicians) across Primary Care Service Areas (N = 6542): (1) American Medical Association (AMA) Masterfile nonfederal, office-based physicians per total population and (2) office-based primary care clinical full-time equivalents (FTEs) per Medicare beneficiary derived from Medicare claims.
  
  
  METHODS
  Annual individual-level outcomes (mortality, ambulatory care sensitive condition [ACSC] hospitalizations, and Medicare program spending), adjusted for individual patient characteristics and geographic area variables.
  
  
  RESULTS
  Marked variation was observed in the primary care physician workforce across areas, but low correlation was observed between the 2 primary care workforce measures (Spearman r = 0.056; P < .001). Compared with areas with the lowest quintile of primary care physician measure using AMA Masterfile counts, beneficiaries in the highest quintile had fewer ACSC hospitalizations (74.90 vs 79.61 per 1000 beneficiaries; relative rate [RR], 0.94; 95% confidence interval [CI], 0.93-0.95), lower mortality (5.38 vs 5.47 per 100 beneficiaries; RR, 0.98; 95% CI, 0.97-0.997), and no significant difference in total Medicare spending ($8722 vs $8765 per beneficiary; RR, 1.00; 95% CI, 0.99-1.00). Beneficiaries residing in areas with the highest quintile of primary care clinician FTEs compared with those in the lowest quintile had lower mortality (5.19 vs 5.49 per 100 beneficiaries; RR, 0.95; 95% CI, 0.93-0.96), fewer ACSC hospitalizations (72.53 vs 79.48 per 1000 beneficiaries; RR, 0.91; 95% CI, 0.90-0.92), and higher overall Medicare spending ($8857 vs $8769 per beneficiary; RR, 1.01; 95% CI, 1.004-1.02).
  
  
  CONCLUSIONS
  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.
authors: Center for Health Policy Research, Dartmouth Institute for Health Policy and Clinical Practice, Dartmouth Medical School, Lebanon, NH 03766, USA. chiang-hua.chang@dartmouth.edu
authors: Chiang-Hua
authors: CH
authors: Chang
authors: Therese A
authors: TA
authors: Stukel
authors: Ann Barry
authors: AB
authors: Flood
authors: David C
authors: DC
authors: Goodman
references: JAMA. 2008 Sep 10;300(10):1174-80
references: 18780846
references: Am Fam Physician. 2004 Aug 1;70(3):440, 442, 445-6
references: 15317429
references: Health Aff (Millwood). 2010 Mar-Apr;29(3):537-43
references: 20110290
references: N Engl J Med. 2009 Dec 10;361(24):2301-3
references: 19864649
references: Ann Intern Med. 2003 Feb 18;138(4):288-98
references: 12585826
references: N Engl J Med. 2009 Jun 25;360(26):2696-9
references: 19553644
references: Health Serv Res. 1999 Apr;34(1 Pt 2):323-9
references: 10199678
references: Ann Intern Med. 2003 Feb 18;138(4):273-87
references: 12585825
references: JAMA. 1996 Dec 11;276(22):1811-7
references: 8946901
references: J Am Board Fam Pract. 2003 Sep-Oct;16(5):412-22
references: 14645332
references: Perspect Biol Med. 2003 Winter;46(1):69-79
references: 12582271
references: Health Serv Res. 2007 Dec;42(6 Pt 1):2233-51; discussion 2294-323
references: 17995563
references: JAMA. 2009 May 20;301(19):2038-40
references: 19454643
references: Health Aff (Millwood). 2010 May;29(5):799-805
references: 20439864
references: Health Aff (Millwood). 2006 Mar-Apr;25(2):521-31
references: 16522606
references: Milbank Q. 2005;83(3):457-502
references: 16202000
references: Pediatrics. 2010 Jun;125(6):1119-26
references: 20498170
references: Am J Public Health. 1995 Oct;85(10):1402-7
references: 7573625
references: Health Aff (Millwood). 2009 Sep-Oct;28(5):1327-35
references: 19738248
references: Soc Sci Med. 2005 Jul;61(1):65-75
references: 15847962
references: Health Serv Res. 1996 Jun;31(2):191-211
references: 8675439
references: N Engl J Med. 2010 Jan 21;362(3):e7
references: 20054034
references: Health Aff (Millwood). 2009 Jul-Aug;28(4):1136-45
references: 19597213
references: Health Serv Res. 2005 Aug;40(4):1148-66
references: 16033497
references: Health Aff (Millwood). 2005 Jan-Jun;Suppl Web Exclusives:W5-97-W5-107
references: 15769797
references: Health Serv Res. 2003 Feb;38(1 Pt 1):287-309
references: 12650392
references: Health Aff (Millwood). 2008 May-Jun;27(3):w232-41
references: 18445642
references: BMJ. 2004 Mar 13;328(7440):607
references: 15016692