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Background: The distinct pharmacological properties and clinical uses of extended-release naltrexone (XR-NTX) and sublingual buprenorphine-naloxone (BUP-NX) present challenges in analyzing patient outcomes.Methods: We conducted a secondary analysis of a multi-site randomized trial comparing XR-NTX with sublingual BUP-NX treatment for opioid use disorder initiated during inpatient detoxification and continued in outpatient treatment. Urine testing data for non-study opioids from the last 22 weeks of the 24-week trial were analyzed in both a per-protocol sample (n = 474 participants who received at least one dose of medication) and a completers sample (n = 211 participants who received all XR-NTX doses or all BUP-NX prescriptions). The present analyses sought to identify differences in the weekly percentages of opioid-positive urine tests between participants treated with the two medications.Results: The proportion of opioid-positive tests in both conditions was less than 20 % for 21 of the 22 weeks in the per-protocol sample and all 22 weeks in the completers sample. Generalized linear mixed model analyses revealed a significant treatment (XR-NTX vs. BUP-NX) X week (weeks 3-24) interaction in the per-protocol sample but not the completers sample. In the per-protocol analysis, the BUP-NX, compared to XR-NTX, had significantly greater proportions of opioid-positive tests in 14 out of the 22 weeks.Conclusions: Longitudinal modeling approaches that utilize flexible procedures for handling missing data can offer a different perspective on study findings. Results from the present analyses suggest that XR-NTX appeared to be somewhat more effective than BUP-NX in reducing illicit opioid use in the per-protocol sample. [ABSTRACT FROM AUTHOR]

Background: Methamphetamine use is increasing among persons with opioid use disorder (OUD). The study aims were to describe methamphetamine/amphetamine (MA/A) use among patients treated for OUD with buprenorphine/naloxone (BUP-NX) or extended-release naltrexone (XR-NTX), and to explore associations between treatment arm and MA/A use.Methods: Secondary analysis of data from a multi-site, open-label, randomized controlled trial of XR-NTX versus BUP-NX for 24 weeks. The outcome variable was MA/A use defined by either positive urine drug toxicology or self-report. The main predictor was treatment assignment (BUP-NX v. XR-NTX). Longitudinal mixed-effects logistic regression models were fit to model the odds of MA/A use during the study. Additional predictors included study visit and baseline MA/A use.Results: Among the sample of 570 participants with OUD, baseline use of MA/A was observed in 105 (18.4%). There was no significant treatment effect over the study period, though BUP-NX subjects, on average, had about half the odds of MA/A use compared to XR-NTX subjects (OR=0.50; p = 0.051). In the same model, baseline MA/A use and study visit were both significantly associated with MA/A use over time.Conclusion: In this sample of treated OUD patients, nearly a fifth of participants had MA/A use at baseline and the frequency of use did not decline over time: in fact, the odds of use slightly increased for each later visit. These secondary analyses found no significant difference in MA/A use between BUP-NX and XR-NTX treatment arms, however, the observation of less MA/A in the buprenorphine arm merits further investigation.Clinical Trial Registration: ClinicalTrials.gov (NCT02032433). [ABSTRACT FROM AUTHOR]