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.
Keywords: Adolescence; Depression; Depressive symptoms; Universal prevention.