BACKGROUND: Adherence to buprenorphine medication assisted therapy (BMAT) has been associated with reduced relapse in opioid use disorder (OUD) patients, but few studies have assessed the impact of low, intermediate, and high adherence on relapse outcomes.
OBJECTIVE: To examine the impact of BMAT adherence on relapse after BMAT initiation in a real-world sample of OUD patients.
METHODS: OUD patients initiating a new BMAT episode between 2008-2014 were identified in the MarketScan Commercial and Medicaid claims databases (earliest BMAT claim=index date). Patients were followed for 6 months pre-index and at least 12 months postindex. Adherence was measured over 12 months post-index using proportion of days covered (PDC) and patients were grouped into categories: <20%, 20-39%, 40-59%, 60-79%, and ≥80%. Relapse and time to relapse were identified in the 12 months post-index and at any time following index using service-based relapse proxies. Logistic regression and Cox proportional hazards models (CPHM) estimated the impact of PDC on relapse in the 12 months following BMAT initiation and time to relapse anytime following BMAT initiation, respectively, adjusting for baseline patient characteristics.
RESULTS: 16,085 Commercial and 5,688 Medicaid patients qualified for the analysis. Commercial patients in each of the lower PDC groups had significantly increased odds of relapse in the 12 months post-BMAT initiation compared to patients with PDC≥80% (<20%: OR=2.80; 20-39%: OR=2.84; 40-59%: OR=1.88; 60-79%: OR=1.60; all P<0.001). Medicaid patients in the lower PDC groups also had significantly increased odds of relapse in the 12 months post-index compared to patients with PDC≥80% (<20%: OR=2.27; 20-39%: OR=1.95; 40-59%: OR=1.62; 60-79%: OR=1.66; all P<0.01). The CPHM model showed that Commercial patients in each of the lower PDC groups had a significantly higher hazard of relapse any time after BMAT initiation than those with PDC≥80% (<20%: HR=1.96; 20-39%: HR=2.02; 40-59%: HR=1.77; and 60-79%: HR=1.57; all P<0.001). Similarly, in the Medicaid sample, the model showed there was a significantly higher hazard of relapse any time after BMAT initiation in the lower PDC groups compared to PDC≥80% (<20%: HR=1.45; 20-39%: HR=1.48; 40-59%: HR=1.35; and 60-79%: HR=1.28; all P<0.05).
CONCLUSIONS: This study assessed relapse risk across the adherence continuum, finding that OUD patients with all lower levels of BMAT adherence had significantly increased risk of relapse compared to adherent patients (PDC≥80%), providing further evidence that BMAT adherence is associated with better outcomes.
