An online wellness intervention for internalizing symptoms in college students: A multi-site randomized controlled trial evaluating the efficacy of the Common Elements Toolbox (COMET).

Untreated internalizing symptoms among young people is a large public health problem. One way to expand access to care involves developing and disseminating evidence-based online interventions. Previous research has shown that online interventions can be effective, even as single-session interventions (SSIs), and that they are well-received by users. The Common Elements Toolbox (COMET) is composed of four modules derived from various psychotherapy packages. Several open trials and a recent randomized controlled trial (RCT) support the efficacy of COMET, while a recent larger RCT casts doubt on its efficacy. We evaluated the efficacy of the COMET SSI with accompanying online support to promote skill practice vs. an attention-matched waitlist control (WLC). We evaluated group differences in depression, anxiety, and well-being, as well as positive and negative affect among undergraduates (N = 453). Outcomes were assessed 2-, 4-, and 8-weeks post-intervention. Results suggest that, relative to participants in the WLC, participants randomized to COMET experienced decreases in depression (SMD = -0.24, 95% CI: [-0.42, -0.06]) and anxiety (SMD = -0.30, 95% CI: [-0.50, -0.11]), along with small non-significant increases in positive affect (SMD = 0.18, 95% CI: [-0.10, 0.45]) and well-being (SMD = 0.19, 95% CI: [-0.03, 0.40]). Overall, the results provide support for COMET's efficacy as a low-intensity mental health intervention for college students but must be interpreted with caution given high attrition at the last follow-up. PREREGISTRATION: This study was pre-registered on Open Science Framework (OSF) Registries (https://osf.io/sxet7/overview) and on the National Institutes of Health's ClinicalTrials.gov (NCT04740411). Data and statistical code are available upon reasonable request made to the corresponding author.