Sample Size and Power Analysis
The sample size was chosen to ensure sufficient statistical power for the primary outcome, comparing TLC with TLC with MTM among early treatment nonresponders. Sample size formula for the number of early treatment nonresponders needed for the primary analysis was equivalent to standard calculations for 2-group randomized trials. We reestimated the sample size in April 2019 using blinded data to estimate the proportion of early treatment nonresponders and proportion achieving prolonged abstinence across both groups. Seven hundred participants provided approximately 90% power to detect a 10% difference in 6-month prolonged abstinence between TLC and TLC with MTM, assuming 80% of the sample would be early treatment nonresponders and 10% would achieve prolonged abstinence with TLC.