Testing the Universality of the Effects of the Communities That Care Prevention System for Preventing Adolescent Drug Use and Delinquency

Background/Purpose: Universal community-oriented interventions are an important tool in the prevention of youth health and behavior problems. Like universal interventions in other domains, community-based initiatives are usually designed to reach and affect a community's youth equally. Understanding differential effectiveness of an intervention that was designed to be universal is important because it provides more complete information about how the program operates and for whom and under what conditions it is most effective. If the program is not equally effective across individuals or groups, the results could be used to suggest changes to the program's content, methods, or intensity. The present study examined whether the previously established significant effects of the universal, community-based Communities That Care (CTC) prevention system on the prevalence of adolescent substance use and the variety of delinquent behaviors (Hawkins et al. 2009) held equally for boys and girls and in risk-related subgroups defined by early substance use, early delinquency, and high levels of community-targeted risk at baseline. Methods/Results: Interaction analyses of data from a panel of 4407 students followed from grade 5 to grade 8 in the randomized trial of CTC in 12 matched community pairs demonstrated that CTC reduced students' substance use and delinquency equally across risk-related subgroups and gender, with two exceptions: the effect of CTC on reducing past month alcohol and smokeless tobacco use, and past 2-week binge drinking in 8th grade, was stronger for boys than girls, and the impact of CTC on reducing 8th grade delinquency was stronger for students who were not involved in crime at baseline in 5th grade. Conclusions/Implications: CTC is a community prevention system designed to prevent adolescent drug use and delinquency community-wide and universally across individuals and subgroups in the community. The results from this study showed little evidence for differential effectiveness of CTC across risk-related subgroups. In the few instances where differential effectiveness was found, CTC appeared to have slightly stronger effects in lowering boys' alcohol use and in inhibiting delinquent behavior among those who had not yet initiated delinquency at baseline.