title: Community Health Center Use After Oregon's Randomized Medicaid Experiment.
abstract: OBJECTIVE
  There is debate about whether community health centers (CHCs) will experience increased demand from patients gaining coverage through Affordable Care Act Medicaid expansions. To better understand the effect of new Medicaid coverage on CHC use over time, we studied Oregon's 2008 randomized Medicaid expansion (the "Oregon Experiment").
  
  
  METHODS
  We probabilistically matched demographic data from adults (aged 19-64 years) participating in the Oregon Experiment to electronic health record data from 108 Oregon CHCs within the OCHIN community health information network (originally the Oregon Community Health Information Network) (N = 34,849). We performed intent-to-treat analyses using zero-inflated Poisson regression models to compare 36-month (2008-2011) usage rates among those selected to apply for Medicaid vs not selected, and instrumental variable analyses to estimate the effect of gaining Medicaid coverage on use. Use outcomes included primary care visits, behavioral/mental health visits, laboratory tests, referrals, immunizations, and imaging.
  
  
  RESULTS
  The intent-to-treat analyses revealed statistically significant differences in rates of behavioral/mental health visits, referrals, and imaging between patients randomly selected to apply for Medicaid vs those not selected. In instrumental variable analyses, gaining Medicaid coverage significantly increased the rate of primary care visits, laboratory tests, referrals, and imaging; rate ratios ranged from 1.27 (95% CI, 1.05-1.55) for laboratory tests to 1.58 (95% CI, 1.10-2.28) for referrals.
  
  
  CONCLUSIONS
  Our results suggest that use of many different types of CHC services will increase as patients gain Medicaid through Affordable Care Act expansions. To maximize access to critical health services, it will be important to ensure that the health care system can support increasing demands by providing more resources to CHCs and other primary care settings.
authors.affiliation: Oregon Health & Science University, Department of Family Medicine, Portland, Oregon OCHIN, Inc, Portland, Oregon.
authors.forename: Jennifer E
authors.initials: JE
authors.lastname: DeVoe
authors.affiliation: Oregon Health & Science University, Department of Family Medicine, Portland, Oregon Department of Public Health and Preventive Medicine, Division of Biostatistics, Oregon Health & Science University, Portland, Oregon.
authors.forename: Miguel
authors.initials: M
authors.lastname: Marino
authors.affiliation: OCHIN, Inc, Portland, Oregon Kaiser Permanente Northwest Center for Health Research, Portland, Oregon.
authors.forename: Rachel
authors.initials: R
authors.lastname: Gold
authors.affiliation: OCHIN, Inc, Portland, Oregon.
authors.forename: Megan J
authors.initials: MJ
authors.lastname: Hoopes
authors.affiliation: OCHIN, Inc, Portland, Oregon.
authors.forename: Stuart
authors.initials: S
authors.lastname: Cowburn
authors.affiliation: Department of Public Health and Preventive Medicine, Division of Biostatistics, Oregon Health & Science University, Portland, Oregon.
authors.forename: Jean P
authors.initials: JP
authors.lastname: O'Malley
authors.affiliation: Oregon Health & Science University, Department of Family Medicine, Portland, Oregon.
authors.forename: John
authors.initials: J
authors.lastname: Heintzman
authors.affiliation: Office of Health Analytics, Oregon Health Authority, Portland, Oregon.
authors.forename: Charles
authors.initials: C
authors.lastname: Gallia
authors.affiliation: Center for Health System Effectiveness, Department of Emergency Medicine, Oregon Health & Science University, Portland, Oregon.
authors.forename: K John
authors.initials: KJ
authors.lastname: McConnell
authors.affiliation: OCHIN, Inc, Portland, Oregon.
authors.forename: Christine A
authors.initials: CA
authors.lastname: Nelson
authors.affiliation: Oregon Health & Science University, Department of Family Medicine, Portland, Oregon.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Huguet
authors.affiliation: Oregon Health & Science University, Department of Family Medicine, Portland, Oregon bailstef@ohsu.edu.
authors.forename: Steffani R
authors.initials: SR
authors.lastname: Bailey
mesh_terms: D000328:Adult; D003151:Community Health Centers / Q000706:statistics & numerical data*; D005260:Female; D006297:Health Services Accessibility; D006801:Humans; D057194:Intention to Treat Analysis; D008297:Male; D008484:Medicaid; D017057:Medically Uninsured; D008875:Middle Aged; D009922:Oregon; D058991:Patient Protection and Affordable Care Act; D011320:Primary Health Care / Q000706:statistics & numerical data*; D014481:United States; D055815:Young Adult
keywords: ACA; Medicaid; Oregon Experiment; Patient Protection and Affordable Care Act; community health centers; health policy; practice-based research; primary care utilization; vulnerable populations