Sample Size
Power was calculated a priori for the primary outcome of the 3-month (90-day) dose of methadone. We anticipated that dose escalations after initial titration would be recommended for approximately 70% of participants in the TAU cohort in that time frame, basing this approximation on discussions with clinic staff on the proportion of patients who receive dose increases at this opioid treatment program. Thus, 60 participants per group would yield a power of 0.80 to detect a group difference if the corresponding rate in the intervention group was 44% or lower (a maximum of 26 of 60 participants), using a Fisher exact test with a 2-tailed α level of .05. This is equivalent to an odds ratio of 3.03 or a Cohen 