Depression contributes about 2% to the global burden of disease. A first onset of depressive disorder or subsyndromal depressive symptoms is common in adolescence, indicating that early prevention is a priority. However, trials of preventive interventions for depression in youths show conflicting results. This systematic review and meta-analysis investigated the effectiveness of group-based cognitive behavioral therapy (GB-CBT) as a preventive intervention targeting subsyndromal depression in children and adolescents. In addition, the impact of different covariates (type of comparator and use of booster sessions) was assessed. Relevant articles were identified from previous systematic reviews, and supplemented with an electronic search spanning from 01/09/2014 to 28/02/2018. The retrieved articles were assessed for eligibility and risk of bias. Relevant data were extracted. Intervention effectiveness was pooled using a random-effects model and the impact of covariates assessed using meta-regression. 38 eligible articles (34 trials) were obtained. The analysis showed GB-CBT to significantly reduce the incidence (relative risk 0.43, 95% CI 0.21-0.87) and symptoms (Cohen's d -0.22, 95% CI -0.32 to -0.11) of depression at post-test compared to all controls. Comparisons with passive comparators suggested that the effect decayed over time. However, compared to active controls, a significant intervention effect was evident only after 12 month or more. Our results suggest that the preventive effect of GB-CBT wears off, but still lasts longer than the effect of active comparators. Only a few studies included booster sessions, precluding firm conclusions. Future studies should clarify to what extent maintenance strategies can prolong the preventive effect of GB-CBT.

Background: Depression in adolescence is associated with increased healthcare consumption in adulthood, but prior research has not recognized the heterogeneity of depressive disorders. This paper investigated the additional healthcare usage and related costs in mid-adulthood for individuals with adolescent depression, and examined the mediating role of subsequent depression in early adulthood.

Methods: This study was based on the Uppsala Longitudinal Adolescent Depression Study, initiated in Sweden in the early 1990s. Depressive disorders were assessed in adolescence (age 16-17) and early adulthood (age 19-30). Healthcare usage and related costs in mid-adulthood (age 31-40) were estimated using nationwide population-based registries. Participants with specific subtypes of adolescent depression (n = 306) were compared with matched non-depressed peers (n = 213).

Results: Women with persistent depressive disorder (PDD) in adolescence utilized significantly more healthcare resources in mid-adulthood. The association was not limited to psychiatric care, and remained after adjustment for individual and parental characteristics. The total additional annual cost for a single age group of females with a history of PDD at a population level was estimated at 3.10 million USD. Depression recurrence in early adulthood mediated the added costs for psychiatric care, but not for somatic care.

Limitations: Primary health care data were not available, presumably resulting in an underestimation of the true healthcare consumption. Estimates for males had limited precision due to a relatively small male proportion.

Conclusions: On a population level, the additional healthcare costs incurred in mid-adulthood in females with a history of adolescent PDD are considerable. Early treatment and prevention should be prioritized.

Background: Adolescent depression has negative health and economic outcomes in the shortand long-term. Indicated preventive interventions, in particular group based cognitive behavioural therapy (GB-CBT), are ef-fective in preventing depression in adolescents with subsyndromal depression. However, little is known about the cost-effectiveness of these interventions. Methods: A Markov cohort model was used to conduct cost-effectiveness analyses comparing a GB-CBT indicated preventive intervention for depression, to a no-intervention option in a Swedish setting. Taking a time horizon of 5and 10 years, incremental differences in societal costs and health benefits expressed as differences in the proportion of cases of depression prevented, and as quality adjusted life years (QALYs) gained were estimated. Through univariate and probabilistic sensitivity analyses, the robustness of the results was explored. Costs, presented in 2018 USD, and effects were discounted at a yearly rate of 3%. Results: The base-case analysis showed that GB-CBT indicated preventive intervention incurred lower costs, prevented a larger proportion of cases of depression and generated higher QALYs compared to the no -intervention option for both time horizons. Offering the intervention was even a cost saving strategy and demonstrated a probability of being cost-effective of over 95%. In the sensitivity analyses, these results were robust to the modelling assumptions. Limitations: The study considered a homogeneous cohort and assumed a constant annual decay rate of the relative treatment effect. Conclusions: GB-CBT indicated preventive interventions for depression in adolescence can generate good value for money compared to leaving adolescents with subsyndromal depression untreated.