Evaluating the impact of school-based interventions on youth loneliness: A systematic review and meta-analysis

Aims: Youth loneliness is a prevalent global health concern with lifelong health ramifications. Schools, as children's primary peer environments, are promising settings for loneliness interventions. However, school-based interventions are highly heterogeneous and no review to date has evaluated their effect on loneliness specifically. Methods: A systematic review was conducted to identify studies of school-based interventions measuring loneliness as an outcome in children and young people aged up to 18. Meta-analyses were conducted using a random-effects model to pool effect sizes and examine the significance of intervention characteristics and study design. Reported implementation factors were extracted and narratively synthesised. Results: Thirty-eight studies were included in meta-analysis, of which 19 were randomized controlled trials, ten were non-randomized controlled, and nine were single group studies. A small-to-moderate effect estimate was found, Hedges' g = -0.42 [95% CI: -0.71, -0.13], p = .006, and sub-group analyses indicated that differences in study design and quality did not result in significantly different effect estimates. Psychological interventions, followed by social and emotional skills training, produced significantly higher effects estimates compared with other intervention types. Conclusions: Findings indicate that school-based interventions are effective in reducing youth loneliness. However, study heterogeneity, reporting inconsistencies, and a wide prediction interval indicates this finding should be interpreted with caution. Future research may benefit from improved measurement and reporting of implementation factors, particularly dosage and fidelity.