The effect of Medicaid expansion on state-level utilization of buprenorphine for opioid use disorder in the United States

Background: Research on the impact of Medicaid expansion on buprenorphine utilization has largely focused on the Medicaid program. Less is known about its associations with total buprenorphine utilization and non-Medicaid payers. Methods: Monthly prescription data (June 2013-May 2018) for proprietary and generic sublingual as well as buccal buprenorphine products were purchased from IQVIA®. Population-adjusted state-level utilization measures were constructed for Medicaid, commercial insurance, Medicare, cash, and total utilization. A difference-in-differences (DID) approach with population weights estimated the association between Medicaid expansion and buprenorphine utilization, while controlling for treatment capacity. Results: Monthly total buprenorphine prescriptions increased by 68% overall and increased 283% for Medicaid, 30% for commercial insurance, and 143% for Medicare. Cash prescriptions decreased by 10%. The DID estimate for Medicaid expansion was not statistically significant for total utilization (−19.780, 95% CI = −45.118, 5.558, p = .123). For Medicaid buprenorphine utilization, there was a significant increase of 27.120 prescriptions per 100,000 total state residents (95% CI = 9.458, 44.782, p = .003) in expansion states versus non-expansion states post-Medicaid expansion. Medicaid expansion had a negative effect on commercial insurance (DID estimate = −37.745, 95% CI = −62.946, −12.544, p = .004), cash utilization (DID estimate = −6.675, 95% CI = −12.627, −0.723, p = .029), and Medicare utilization (DID estimate = −1.855, 95% CI = −3.697, −0.013, p = .048). Discussion: The associations between Medicaid expansion and buprenorphine utilization varied across different types of payers, such that the overall impact of Medicaid expansion on buprenorphine utilization was not significant.