Factors Influencing the Effectiveness of Communities That Care in Germany: A Meta-Analysis

Abstract Background Communities That Care (CTC) is an internationally recognized prevention support system that enables communities to adopt a science-based strategy to prevent youth problem behavior. Through capacity building, CTC promotes system change, such as increased collaboration for prevention. This study examines the variation in CTC's effectiveness across German communities and explores factors contributing to this variation. Methods A non-randomized cluster-controlled study was conducted with twelve a priori matched pairs of CTC-implementing and comparison communities. The primary short-term outcome is the adoption of an evidence-based strategy for prevention (adoption), while secondary outcomes include prevention collaboration (PC) and sectoral collaboration (SC). Data from 205 community key informants were analyzed, calculating community-specific means for each outcome. A meta-analysis assessed the variation in effects across the matched pairs, and meta-regressions examined implementation quality and community characteristics as potential predictors. Results The results show a positive overall effect of CTC on adoption (g = 0.57, p = .02), with significant variation in effect sizes (p < .05) and substantial heterogeneity (I² = .59) between matched pairs. Implementation quality is a significant predictor for adoption (b = 1.61, p = .02), explaining 40.5% of the heterogeneity. Additionally, CTC had a stronger effect on adoption (b = 1.612, p = .16, r² = .163) and SC (b = 1.738, p = .25, r² = .104) in deprived communities as well as on SC in peripheral communities (b = 0.42, p = .18, r² = .248). Discussion The results underscore the critical role of high-quality implementation in CTC's effectiveness, aligning with expected mechanisms. CTC appears to be particularly effective in deprived and peripheral areas. Further research is necessary to fully understand the variability in effect sizes and inform strategies to optimize CTC's implementation and effectiveness. Key messages • The successful adoption of evidence-based prevention strategies relies on high-quality implementation of CTC. • Community characteristics may influence CTC’s effectiveness.