Treatment effect modifiers in a randomized trial of the good behavior game during middle childhood.

Objective: Two key treatment effect modifiers-implementation variability and participant cumulative risk status-are examined as predictors of disruptive behavior outcomes in the context of a large cluster randomized controlled trial of a universal, school-based behavior management intervention. The core components of the Good Behavior Game (GBG) are classroom rules, team membership, monitoring behavior, and positive reinforcement. Children work in teams to win the game, which is played alongside a normal classroom activity, during which their teacher monitors infractions to classroom rules. Teams with four or fewer infractions at the end of the game win and are rewarded. Method: Seventy-seven English primary schools (N = 3,084 children, aged 6-7) were randomly assigned to deliver the GBG or continue their usual practice over 2 years. Results: Intent-to-treat analysis found no discernible impact of the intervention on children's disruptive behavior. Additionally, subgroup analyses revealed no differential gains among children at low, moderate or high levels of cumulative risk exposure (CRE). However, complier average causal effect estimation (CACE) using dosage as a compliance marker identified a large, statistically significant intervention effect (d = -1.35) among compliers (>1,030 min of cumulative intervention exposure). Furthermore, this compliance effect varied by participant CRE, such that children at high and low levels of exposure experienced significantly greater and lesser reductions in disruptive behavior, respectively. Conclusions: These findings highlight the importance of optimizing implementation and demonstrate the utility of CRE as a theoretically informed approach to subgroup moderator analysis. Implications are discussed and study strengths and limitations are noted. (PsycInfo Database Record (c) 2021 APA, all rights reserved).