Efficacy of a single session intervention for depression in online workers: A randomized controlled trial with transdiagnostic mental health outcomes

Introduction: Digital single-session interventions (SSIs) have shown promise in the treatment of depression and anxiety in youth. We studied the efficacy of an SSI previously reported to be efficacious, the Common Elements Toolbox (COMET), in a large sample of adult online workers (N=828). Methods: We conducted an investigator-blinded, pre-registered randomized controlled trial (NCT05379881; pre-registration https://osf.io/63yzh) comparing the COMET-SSI to an 8-week waiting list control (WLC). Participants recruited from the online workspace Prolific were assessed for depression, anxiety, work and social functioning, psychological well-being, and emotion regulation at baseline and post-intervention at weeks 2, 4, and 8. The main outcomes were short (2-week) and longer-term (8-week) changes in depression and anxiety. The secondary outcomes were the 8-week changes in functioning, well-being, and emotion regulation. Analyses were conducted according to the intent-to-treat (ITT) principle with imputation (ITT-imputed), without imputation (ITT-unimputed), and using a per-protocol (PP) sample. Additionally, we conducted sensitivity analyses to identify inattentive responders. Results: The sample was 61.96% women (n = 513) with a mean age of 35.74 (SD = 11.93). Almost all of the participants met the criteria to screen for depression or anxiety on a validated screening scale. There were no statistically or clinically significant differences between the conditions in any of the outcomes at any of the time points regardless. Removing inattentive respondents did not change the pattern of results. Discussion: Our results do not support the use of SSIs like COMET in online workers. Future work should explore alternative ways of intervening with online workers.