Medicaid expansion and treatment for opioid use disorders in Oregon: an interrupted time-series analysis

BACKGROUND: The study examined the association of the Affordable Care Act’s 2014 Medicaid expansion on the use of psychosocial services and pharmacotherapies for opioid use disorders among Oregon Medicaid recipients. METHODS: Logistic regression analysis examined utilization of care before (January 1, 2010–December 31, 2013) and after Medicaid expansion in Oregon (January 1, 2014–December 31, 2016). RESULTS: Adult membership in the Oregon Health Plan (Medicaid) increased 180% following Medicaid expansion (2013 = 172,539; 2014 = 482,081) and the number with a diagnosis of OUD nearly doubled (2013 = 6808; 2014 = 13,418). More individuals received psychosocial services (2013 = 4714; 2014 = 8781) and medications (2013 = 3464; 2014 = 6093) for opioid use disorder. The percent of patients receiving psychosocial services (69% to 65%) and the percent of individuals receiving pharmacotherapy (57% to 45%) declined primarily because of a decline in the proportion receiving care in an opioid treatment program (2013 = 41%; 2014 = 33%). Odds of accessing any psychosocial service increased by 8% per year from 2010 to 2013 (AOR = 1.08; 95% CI 1.06–1.11) with an 18% immediate decline associated with Medicaid expansion in 2014 (AOR = 0.82; 95% CI 0.76–0.87). Following Medicaid expansion, the odds of accessing psychosocial services increased 8% per year (2014 through 2016) (AOR = 1.08; 95% CI 1.06–1.11). Use of medications for opioid use disorder found no change in the odds of use in the years prior to Medicaid expansion, an immediate 36% (AOR = 0.64; 95% CI 0.60–0.68) decline in 2014, and a 13% increase per year in 2015 and 2016 (AOR = 1.13; 95% CI 1.09–1.16). CONCLUSION: The number of Medicaid recipients with an opioid use disorder who received psychosocial and pharmacological services increased substantially following Oregon’s Medicaid expansion in 2014. There was a decline, however, in the proportion of individuals with an opioid use disorder receiving care in opioid treatment programs. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s13722-019-0160-6) contains supplementary material, which is available to authorized users.