Change in participant engagement during a family-based preventive intervention: ups and downs with time and tension

The efficacy of preventive interventions is related to both the delivery of content and the uptake of that content. Although much research has focused on the quality of delivery, few studies have examined the factors that influence uptake. This study examines how and why participants' engagement-conceptualized as a dynamic process wherein participants interact with each other, the interventionists, and the intervention curriculum-changes over time. We apply growth curve models to repeated measures of engagement obtained from 252 families during a 7-week intervention trial. In the models, we examine (a) whether and how engagement changes over time, and the extent of between-person differences in change; and (b) how those changes and differences are related to chronic and session-specific aspects of family tension, while also controlling for differences across parent sex and 2 versions of the Strengthening Families Program: For Parents and Youth Ages 10-14 (SFP 10-14). Results show that, on average, engagement increased over time, linearly with some deceleration, with substantial differences in both level and rates of change. Higher in-session chronic family tension was related to lower initial levels of engagement but not rates of change. Sessions when families displayed more session-specific tension were characterized by different levels of engagement for parents, depending on their level of chronic tension. Overall, our results highlight the importance of considering engagement as a dynamic construct that changes over time in complex ways. Further understanding of the many factors that influence engagement can promote both better delivery and better uptake of intervention curriculum.