Abstract
Objective: Ineligibility for and refusal to participate in randomized controlled trials (RCTs) can potentially lead to unrepresentative study samples and limited generalizability of findings. We examined the rates of exclusion and refusal in RCTs that have studied impact on suicide-related outcomes in the US. Data Sources: PubMed, the Cochrane Library, the Campbell Collaboration Library of Systematic Reviews, CINAHL, PsycINFO, and Education Resources Information Center were searched from January 1990 to May 2020 using the terms (suicide prevention) AND (clinical trial). Study Selection: Of 8,403 studies retrieved, 36 RCTs assessing effectiveness on suicide-related outcomes in youth (≤ 25 years old) conducted in the US were included. Data Extraction: Study-level data were extracted by 2 independent investigators for a random-effects meta-analysis and meta-regression. Results: The study participants (N = 13,264) had a mean (SD) age of 14.87 (1.58) years and were 50% male, 23% African American, and 24% Hispanic. The exclusion rate was 36.4%, while the refusal rate was 25.5%. The exclusion rate was significantly higher in the studies excluding individuals not exceeding specified cutoff points of suicide screening tools (51.2%; adjusted linear coefficient [β] = 1.30, standard error [SE] = 0.15; P = .041) and individuals not meeting the age or school grade criterion (45.9%; β = 1.37, SE = 0.13; P = .005). Conclusions: The rates of exclusion and refusal in youth prevention interventions studying impact on suicide-related outcomes were not as high compared to the rates found in other mental and behavioral interventions. While there was strong racial/ethnic group representation in RCTs examining youth suicide-related outcomes, suicide severity and age limited eligibility.