Limitations
There were several important limitations in this study. First, a fully powered trial is needed to confirm the results due to the small sample size, including the causal pathways of the intervention using formal mediation analyses across multiple time points and subgroup analysis to examine how the effects may differ between groups (eg, those who are and are not receiving mental health treatment). Second, it is unknown whether the effects were maintained because there was no follow-up time point. Third, the primary outcomes were measured using self-report scales during unblinded outcome assessments, raising possible sources of bias. Fourth, Mello users, but not the control group, received brief weekly phone calls, and although these were not therapeutic in content, they could not be ruled out as contributing to the effects. It is highly possible that these calls contributed to engagement, and considering this support may not be scalable, engagement would likely be lower in the “real world” [