Statistical Analysis
Analyses were conducted between October 1, 2019, and April 30, 2020. Outcomes were analyzed in accordance with randomization assignments, following an intention-to-treat approach. Descriptive statistics with central tendencies and spread were used for continuous variables; distributions and percentages were used for categorical variables. Unpaired We adopted a second, more stringent analysis (subanalysis 1) to account for the potential barrier to analyzing group differences on the 90th-day methadone dose: a missed dose on the 90th day or a temporary need for a lower dose on that day due to 2 or more consecutive missed days (in line with standard opioid treatment program dosing protocols) just before the 90th day would preclude a stabilization dose of methadone, which would have potentially hidden any group differences. This analysis included only participants who had been retained for 90 days, who missed no days within the last 14 days preceding the 90th day, and whose daily dose of methadone had been stable for the 2 weeks before day 90. The rationale was that this would allow sufficient time for any therapeutically necessary dose changes to occur. We then assessed between-group differences in mean 90-day methadone dose for stable-dose participants.Group differences were tested with χ