Estimates of Within-Arm and Between-Arm Differences for Primary and Secondary Outcomes
Pain, pain
Abbreviations: BPI, Brief Pain Inventory; NA, not applicable; PROMIS-GH, Patient-Reported Outcomes Measurement Information System–Global Health.For each outcome, estimates are derived from a linear mixed model with baseline means constrained to be equal across study arms. The dependent variable vector included the prerandomization baseline (week 0) assessment, as well as all postrandomization assessments (for BPI worst pain, at weeks 4, 10, 14, 18, 22, and 24, and for all other outcomes at weeks 10, 18, and 26). The independent variables were the randomization stratification variables (accrual site and baseline opioid use), treatment arm, week (categorical), and the arm-by-week interaction. A patient-level random intercept was included in the model to account for the repeated outcome measurements within patients.Calculated as the mean between-arm difference divided by the pooled SD of the baseline scores.