title: Primary care physicians' links to other physicians through Medicare patients: the scope of care coordination.
abstract: BACKGROUND
  Primary care physicians are expected to coordinate care for their patients.
  
  
  OBJECTIVE
  To assess the number of physician peers providing care to the Medicare patients of a primary care physician.
  
  
  METHODS
  Cross-sectional analysis of claims data.
  
  
  METHODS
  Fee-for-service Medicare in 2005.
  
  
  METHODS
  2284 primary care physicians who responded to the 2004 to 2005 Community Tracking Study Physician Survey.
  
  
  METHODS
  Primary patients for each physician were defined as beneficiaries for whom the physician billed for more evaluation and management visits than any other physician in 2005. The number of physician peers for each physician was the sum of other unique physicians that the index physician's primary patients visited plus other unique physicians who served as the primary physician for each of the index physician's nonprimary patients during 2005.
  
  
  RESULTS
  The typical primary care physician has 229 (interquartile range, 125 to 340) other physicians working in 117 (interquartile range, 66 to 175) practices with which care must be coordinated, equivalent to an additional 99 physicians and 53 practices for every 100 Medicare beneficiaries managed by the primary care physician. When only the 31% of a primary care physician's primary patients who had 4 or more chronic conditions was considered, the median number of peers involved was still substantial (86 physicians in 36 practices). The number of peers varied with geographic region, practice type, and reliance on Medicaid revenues.
  
  
  CONCLUSIONS
  Estimates are based only on fee-for-service Medicare patients and physician peers, and the number of peers is therefore probably an underestimate. The modest response rate of the Community Tracking Study Physician Survey may bias results in unpredictable directions.
  
  
  CONCLUSIONS
  In caring for his or her own primary and nonprimary patients during a single year, each primary care physician potentially must coordinate with a large number of individual physician colleagues who also provide care to these patients.
  
  
  BACKGROUND
  National Institute on Aging, American Medical Group Association, and the Robert Wood Johnson Foundation.
authors.affiliation: Center for Studying Health System Change, Washington, DC 20024, USA. mpham@hschange.org
authors.forename: Hoangmai H
authors.initials: HH
authors.lastname: Pham
authors.forename: Ann S
authors.initials: AS
authors.lastname: O'Malley
authors.forename: Peter B
authors.initials: PB
authors.lastname: Bach
authors.forename: Cynthia
authors.initials: C
authors.lastname: Saiontz-Martinez
authors.forename: Deborah
authors.initials: D
authors.lastname: Schrag
mesh_terms: D003266:Continuity of Patient Care / Q000458:organization & administration*; D003430:Cross-Sectional Studies; D018588:Fee-for-Service Plans; D006801:Humans; D006278:Medicare / Q000458:organization & administration*; D010821:Physicians, Family / Q000458:organization & administration*; D012017:Referral and Consultation / Q000458:organization & administration; D014481:United States