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

Abstract

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. 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. 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. 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. 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).