Background: Timely treatment initiation upon opioid use disorder (OUD) diagnosis is critical for improving outcomes.

Objective: Examine initiation and sustained engagement with medications for OUD (MOUD) and behavioral therapy (BHV) among Medicaid beneficiaries with OUD.

Methods:Retrospective cohort study using Medicaid claims data (2010-2019). We included beneficiaries aged 18-64 years with OUD diagnosis and continuous Medicaid enrollment for six months pre-diagnosis (baseline) and three months post-diagnosis (follow-up); those with Medicare-Medicaid enrollment, baseline MOUD use, or OUD remission were excluded. We categorized individuals into five groups based on their initial treatment within one month post-diagnosis: BHV, buprenorphine (BUP)±BHV, methadone (MTD)±BHV, naltrexone (NTX)±BHV, other combinations, and no treatment. Among those initiating treatment (MOUD or BHV), we defined sustained engagement as remaining on initial treatment during follow-up. We used logistic regression to assess sustained engagement by treatment type, adjusting for demographic and clinical covariates.

Results:Among 1,455,967 beneficiaries, 33.9% received no treatment first month post-diagnosis. Among those who did, BHV was most common (75.1%), followed by BUP±BHV (14.6%) and MTD±BHV (8.4%). Median time to MOUD initiation was 2 days (IQR:1-9), shortest in MTD±BHV (1 day, IQR:1-6). Sustained engagement rates were 46.8% (BHV), 67.7% (BUP±BHV), 77.0% (MTD±BHV), and 43.2% (NTX±BHV). Compared to BUP, NTX±BHV had lower engagement (adjusted odds ratio [aOR] 0.34, 95% CI 0.33-0.35), while MTD±BHV had higher engagement (1.69, 1.66-1.72).

Conclusion:Our findings emphasize the need for strategies to improve sustained engagement of MOUDs, especially NTX as it is known to reduce risk of relapse, and support policies ensuring timely access to effective OUD treatments.