When is it time to revise or adapt our prevention programs? Introduction to Special Issue on using baseline target moderation to assess variation in prevention impact

Adaptation of preventive interventions to increase their impact can be advanced by identifying subgroups or specific contexts where program effects appear stronger or weaker. But how do we know where to look for effect heterogeneity in ways that will inform successful adaptation? This paper introduces a special issue that brings together research across prevention science sub-disciplines that adopted baseline target moderated mediation (BTMM) designs to search for effect heterogeneity and guide adaptation of established prevention programs. For this special issue intervention  scientists analyzed data from randomized trials using BTM and BTMM models, evaluating evidence for variation in intervention impact for trials spanning different health outcomes, different developmental periods, and different social units. This introduction provides a brief summary of the various patterns of effect reported in these papers, noting that the most common pattern involved compensatory effects (those beginning the trial with greater risk or fewer protective factors benefit the most), but other patterns including rich-get-richer and partially iatrogenic effects were also detected. This paper ends with a discussion of methodological and substantive implications of these findings for future prevention research, including next-generation prevention trials.