Attrition and adherence in smartphone-delivered interventions for mental health problems: A systematic and meta-analytic review.

Although the efficacy of smartphone-delivered interventions for mental health problems is emerging, randomized controlled trials (RCTs) of smartphone interventions are characterized by high rates of attrition and low adherence. High attrition and low adherence may threaten the validity of RCT findings, so a better understanding of these phenomena is needed. We examined attrition and adherence in 70 RCTs of smartphone interventions. METHOD: Four online databases were searched for RCTs of mental health interventions delivered via smartphones.

= 0.18. Adherence rates were also suboptimal based on our qualitative synthesis; several participants failed to download the intervention, and intervention usage consistently declined over the course of the trial.