The study of effect moderation in youth suicide-prevention studies.

PURPOSE: Suicide is now the second leading cause of death among persons between the ages of adolescents and emerging adults and rates have increased despite more funding and broader implementation of youth suicide-prevention programs. A systematic review was conducted focusing on identifying youth suicide-prevention studies within the United States. This paper reports on the methods utilized for understanding possible moderators of suicide-prevention program outcomes. METHODS: We searched six databases from 1990 through August 2017 to identify studies of suicide-preventive interventions among those under age 26 years. Two independent team members screened search results and sequentially extracted information related to statistical methods of moderation analyses. RESULTS: 69 articles were included in the systematic review of which only 17 (24.6%) explored treatment effect heterogeneity using moderation analysis. The most commonly used analytic tool was regression with an interaction term. The moderators studied included demographic characteristics such as gender and ethnicity as well as individual characteristics such as traumatic stress exposure and multiple prior suicide attempts. CONCLUSIONS: With a greater emphasis from the federal government and funding agencies on precision prevention, understanding which prevention programs work for specific subgroups is essential. Only a small percentage of the reviewed articles assessed moderation effects. This is a substantial research gap driven by sample size or other limitations which have impeded the identification of intervention effect heterogeneity.