DUPLICATE Universal School-Based Depression Prevention "Op Volle Kracht": A Longitudinal Cluster Randomized Controlled Trial
The longitudinal effectiveness of a universal, adolescent school-based depression prevention program Op Volle Kracht (OVK) was evaluated by means of a cluster randomized controlled trial with intervention and control condition (school as usual). OVK was based on the Penn Resiliency Program (PRP) (Gillham et al. Psychological Science, 6, 343–351, 1995). Depressive symptoms were assessed with the Child Depression Inventory (Kovacs 2001). In total, 1341 adolescents participated, Mage = 13.91, SD = 0.55, 47.3 % girls, 83.1 % Dutch ethnicity; intervention group n = 655, four schools; control group n = 735, five schools. Intent-to-treat analyses revealed that OVK did not prevent depressive symptoms, β = −0.01, SE = 0.05, p = .829, Cohen’s d = 0.02, and the prevalence of an elevated level of depressive symptoms was not different between groups at 1 year follow-up, OR = 1.00, 95 % CI = 0.60–1.65, p = .992, NNT = 188. Latent Growth Curve Modeling over the 2 year follow-up period showed that OVK did not predict differences in depressive symptoms immediately following intervention, intercept: β = 0.02, p = .642, or changes in depressive symptoms, slope: β = −0.01, p = .919. No moderation by gender or baseline depressive symptoms was found. To conclude, OVK was not effective in preventing depressive symptoms across the 2 year follow-up. The implications of these findings are discussed.