Commentary/Response: Economic evidence should be routinely collected and reported for studies of intervention effectiveness in mental health. A commentary on Vartiainen et al. (2022).

Anxiety and related disorders are increasingly widespread amongst children and adolescents. Preventing mental health disorders from developing has the potential to realise long-term benefits for children and adolescents. In their paper, 'Economic evidence of preventive interventions for anxiety disorders in children and adolescents-a systematic review', Vartiainen et al. conducted a systematic review to examine economic evidence of interventions for the primary prevention of anxiety disorders in children and adolescents, under 18 years of age. Five articles were eligible for inclusion in the review, of which two were model-based economic evaluations and three conducted alongside randomised controlled trials (RCTs). All five papers used either a cost-effectiveness analysis (CEA) or cost-utility analysis (CUA) as their main analysis. Vartiainen et al. concluded that, due to the small number of studies and relatively small sample sizes, the evidence for the cost-effectiveness of anxiety prevention interventions is weak. In this commentary, the challenges of conducting economic evaluations for prevention interventions are briefly outlined and Vartiainen et al.'s findings are discussed in the context of two further reviews of economic studies, published in 2021. The first focuses on the prevention of anxiety and depression in children and young people and the second takes a broader perspective and also includes interventions for mental health promotion. Both additional reviews note the small number of published economic evaluations, and all three reviews are united in their call for economic evaluations to be conducted alongside all future mental health prevention intervention trials.