Effects of Medication-Assisted Treatment (MAT) for Opioid Use Disorder on Functional Outcomes: A Systematic Review

This systematic review addresses the question: What are the effects of medication-assisted treatment (MAT) that use buprenorphine, buprenorphine combined with naloxone, methadone, or naltrexone for opioid use disorder (OUD) on functional outcomes compared with wait-list, placebo, treatment without medication, any other comparator, or each other (e.g., buprenorphine versus naltrexone)? Functional outcomes investigated included cognitive (e.g., memory), physical (e.g., fatigue), occupational (e.g., employment status), social/behavioral (e.g., criminal activity), and neurological (e.g., balance) function. The authors searched five scientific research databases from inception to 2017 and reference mined existing reviews. Two independent literature reviewers screened 6,292 citations; 1,327 full-text publications were reviewed in detail and 37 studies met inclusion criteria. Critical appraisals assessed studies in detail, and quality of evidence was rated using established criteria. Results were synthesized in meta-analyses and presented in comprehensive evidence tables. Although MAT patients performed significantly better on some functional outcomes than persons with OUD who did not receive MAT, MAT patients performed worse on several cognitive measures than did matched "healthy" controls with no history of substance use disorder (SUD) or OUD. Because of the moderate-to-high risk of bias of most studies, quality of evidence is low or very low for all findings. The small number of studies reporting on outcomes of interest and the weaknesses in the body of evidence prevent making strong conclusions about MAT effects on functional outcomes. The literature shows that more research is needed that targets functional outcomes specifically, and there is, in particular, a lack of research evaluating potential differences in functional effects among medication types, the route of administration, treatment modality, and length of treatment.