title: Using Medicare data to assess nurse practitioner-provided care.
abstract: BACKGROUND
  To mitigate shortages of primary care physicians and ensure access to health care services for a growing number of Medicare beneficiaries, some policy makers have recommended expanding the supply and roles of nurse practitioners (NPs). Little is known about the number of NPs billing Medicare or their practice patterns.
  
  
  OBJECTIVE
  This study examines the geographic distribution and county characteristics of NPs billing Medicare, compares the types and quantities of primary care services provided to Medicare beneficiaries by NPs and primary care physicians, and analyzes the characteristics of beneficiaries receiving primary care from each type of clinician.
  
  
  METHODS
  We performed a cross-sectional analysis of 2008 Medicare administrative data from 959,848 aged and/or disabled beneficiaries continuously enrolled in fee-for-service Medicare during the study period. Outcome measures included geographic distribution of NPs measured by the rate of NPs per 1,000 Medicare beneficiaries by state, average utilization, and patient characteristics.
  
  
  CONCLUSIONS
  States with the highest rate of NPs billing were rural. Over 80% of the payments received by both NPs and primary care physicians were for evaluation and management services. Beneficiaries assigned to an NP were more likely to be female, to be dually eligible for Medicare and Medicaid, and to have qualified for Medicare because of a disability. NPs with assigned beneficiaries were significantly more likely than similar primary care physicians to practice in federally designated primary care shortage areas.
  
  
  CONCLUSIONS
  Approximately 45,000 NPs were providing services to beneficiaries and billing under their own provider numbers in 2008. Aspects of NP practice patterns were different from primary care physicians, and NPs appeared more likely to provide services to disadvantaged Medicare beneficiaries.
authors.affiliation: Mathematica Policy Research, Cambridge, MA. Electronic address: cdesroches@mathematica-mpr.com.
authors.forename: Catherine M
authors.initials: CM
authors.lastname: DesRoches
authors.forename: Jennifer
authors.initials: J
authors.lastname: Gaudet
authors.forename: Jennifer
authors.initials: J
authors.lastname: Perloff
authors.forename: Karen
authors.initials: K
authors.lastname: Donelan
authors.forename: Lisa I
authors.initials: LI
authors.lastname: Iezzoni
authors.forename: Peter
authors.initials: P
authors.lastname: Buerhaus
mesh_terms: D000368:Aged; D003430:Cross-Sectional Studies; D016208:Databases, Factual; D005260:Female; D006801:Humans; D008297:Male; D006278:Medicare / Q000191:economics*; D009722:Nurse Practitioners / Q000191:economics* / Q000600:supply & distribution; D058007:Physicians, Primary Care; D057184:Practice Patterns, Nurses'; D010818:Practice Patterns, Physicians'; D011320:Primary Health Care / Q000458:organization & administration* / Q000706:statistics & numerical data; D011365:Professional Practice Location / Q000706:statistics & numerical data; D012051:Reimbursement Mechanisms / Q000706:statistics & numerical data*; D012959:Socioeconomic Factors; D014481:United States
keywords: Advanced practice nurse; Medicare; Patient characteristics