A Literature Review Examining Primary Outcomes of Medication Treatment Studies for Opioid Use Disorder: What Outcome Should Be Used to Measure Opioid Treatment Success?

Background and objectives: Medications for opioid use disorder (MOUD) reduce opioid use and overdose; however, MOUD clinical trials have used varying primary outcomes to document treatment success. We conducted a literature review to assess and critically examine the methodologies used in MOUD treatment studies.

Methods: Published studies in English that examined MOUD (buprenorphine, methadone, or extended-release naltrexone) were included (N = 20). The methods and frequencies of measuring primary opioid outcomes, including urine drug tests (UDTs) and self-report of opioid use were compared among studies.

Results: A total of 20 studies fit the inclusion criteria. Each study assessed opioid use; only 12 had opioid use as a primary outcome. Other primary outcomes included retention in treatment (N = 6), and two had other primary outcomes (death and opioid withdrawal symptoms). Opioid use was assessed through both self-report and UDTs in 15 studies. Two studies did not use UDTs. Differences were found in the methods used for how opioid use, retention in treatment, self-report of opioid use, and UDTs were measured.

Discussion and conclusions: The different primary outcomes used and operational definitions in each study make comparisons between studies difficult. The use of both self-report and UDTs for opioid use has several advantages, and if possible, researchers should use both measures.

Scientific significance: This is the first review critically examining outcome measures from MOUD treatment studies. Creating a standard for opioid treatment outcomes in MOUD studies will allow for generalizable results that can inform both researchers and clinicians to better care for those with OUD. (Am J Addict 2020;00:00-00).