title: How effective are copayments in reducing expenditures for low-income adult Medicaid beneficiaries? Experience from the Oregon health plan.
abstract: OBJECTIVE
  To determine the impact of introducing copayments on medical care use and expenditures for low-income, adult Medicaid beneficiaries.
  
  
  METHODS
  The Oregon Health Plan (OHP) implemented copayments and other benefit changes for some adult beneficiaries in February 2003.
  
  
  METHODS
  Copayment effects were measured as the "difference-in-difference" in average monthly service use and expenditures among cohorts of OHP Standard (intervention) and Plus (comparison) beneficiaries.
  
  
  METHODS
  There were 10,176 OHP Standard and 10,319 Plus propensity score-matched subjects enrolled during November 2001-October 2002 and May 2003-April 2004 that were selected and assigned to 59 primary care-based service areas with aggregate outcomes calculated in six month intervals yielding 472 observations.
  
  
  RESULTS
  Total expenditures per person remained unchanged (+2.2 percent, p=.47) despite reductions in use (-2.7 percent, p<.001). Use and expenditures per person decreased for pharmacy (-2.2 percent, p<.001; -10.5 percent, p<.001) but increased for inpatient (+27.3 percent, p<.001; +20.1 percent, p=.03) and hospital outpatient services (+13.5 percent, p<.001; +19.7 percent, p<.001). Ambulatory professional (-7.7 percent, p<.001) and emergency department (-7.9 percent, p=.03) use decreased, yet expenditures remained unchanged (-1.5 percent, p=.75; -2.0 percent, p=.68, respectively) as expenditures per service user rose (+6.6 percent, p=.13; +7.9 percent, p=.03, respectively).
  
  
  CONCLUSIONS
  In the Oregon Medicaid program applying copayments shifted treatment patterns but did not provide expected savings. Policy makers should use caution in applying copayments to low-income Medicaid beneficiaries.
authors.affiliation: Division of Public Administration, Mark O. Hatfield School of Government, Portland State University, P.O. Box 751, 506 SW Mill Street, Portland, OR 97207-0751, USA.
authors.forename: Neal T
authors.initials: NT
authors.lastname: Wallace
authors.forename: K John
authors.initials: KJ
authors.lastname: McConnell
authors.forename: Charles A
authors.initials: CA
authors.lastname: Gallia
authors.forename: Jeanene A
authors.initials: JA
authors.lastname: Smith
mesh_terms: D000293:Adolescent; D000328:Adult; D015331:Cohort Studies; D003669:Deductibles and Coinsurance / Q000191:economics*; D005260:Female; D005102:Health Expenditures; D006296:Health Services / Q000191:economics* / Q000706:statistics & numerical data*; D006304:Health Status; D006801:Humans; D007345:Insurance Claim Review; D008297:Male; D008484:Medicaid; D008603:Mental Health; D008875:Middle Aged; D009922:Oregon; D013221:State Health Plans / Q000191:economics* / Q000458:organization & administration; D014481:United States