title: The Impact of Using Mid-level Providers in Face-to-Face Primary Care on Health Care Utilization.
abstract: BACKGROUND
  There has been concern that greater use of nurse practitioners (NP) and physician assistants (PA) in face-to-face primary care may increase utilization and spending.
  
  
  OBJECTIVE
  To evaluate a natural experiment within Kaiser Permanente in Georgia in the use of NP/PA in primary care.
  
  
  METHODS
  From 2006 through early 2008 (the preperiod), each NP or PA was paired with a physician to manage a patient panel. In early 2008, NPs and PAs were removed from all face-to-face primary care. Using the 2006-2010 data, we applied a difference-in-differences analytic approach at the clinic level due to patient triage between a NP/PA and a physician. Clinics were classified into 3 different groups based on the percentage of visits by NP/PA during the preperiod: high (over 20% in-person primary care visits attended by NP/PAs), medium (5%-20%), and low (<5%) NP/PA model clinics.
  
  
  METHODS
  Referrals to specialist physicians; emergency department visits and inpatient admissions; and advanced diagnostic imaging services.
  
  
  RESULTS
  Compared with the low NP/PA model, the high NP/PA model and the medium NP/PA model were associated with 4.9% and 5.1% fewer specialist referrals, respectively (P<0.05 for both estimates); the high NP/PA model and the medium NP/PA model also showed fewer hospitalizations and emergency department visits and fewer advanced diagnostic imaging services, but none of these was statistically significant.
  
  
  CONCLUSIONS
  We find no evidence to support concerns that under a physician's supervision, NPs and PAs increase utilization and spending.
authors.affiliation: *RAND Corporation, Boston, MA †RAND Corporation, Pittsburgh, PA ‡Harvard Medical School §Massachusetts Health Policy Commission, Boston, MA ∥The Center for Clinical and Outcomes Research, Kaiser Permanente ¶Georgia State University School of Public Health, Atlanta, GA.
authors.forename: Hangsheng
authors.initials: H
authors.lastname: Liu
authors.forename: Michael
authors.initials: M
authors.lastname: Robbins
authors.forename: Ateev
authors.initials: A
authors.lastname: Mehrotra
authors.forename: David
authors.initials: D
authors.lastname: Auerbach
authors.forename: Brandi E
authors.initials: BE
authors.lastname: Robinson
authors.forename: Lee F
authors.initials: LF
authors.lastname: Cromwell
authors.forename: Douglas W
authors.initials: DW
authors.lastname: Roblin
mesh_terms: D000293:Adolescent; D000328:Adult; D000553:Ambulatory Care / Q000379:methods / Q000706:statistics & numerical data; D005260:Female; D005845:Georgia; D006801:Humans; D008297:Male; D008875:Middle Aged; D009722:Nurse Practitioners / Q000706:statistics & numerical data*; D010342:Patient Acceptance of Health Care / Q000706:statistics & numerical data*; D010823:Physician Assistants / Q000706:statistics & numerical data*; D011320:Primary Health Care / Q000379:methods / Q000706:statistics & numerical data*; D012017:Referral and Consultation / Q000706:statistics & numerical data*; D055815:Young Adult