High Clinical Trial Attrition Rates for Depression Intervention Apps

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The findings point to major concerns about high dropout rates and study bias in the field of research on smartphone apps for depressive symptom treatment.

Dropout rates in clinical trials that assess the treatment of depression with smartphone applications appear to be worryingly high, potentially endangering the validity of these trials, according to an article published in the Journal of Affective Disorders. Smartphone applications for depression, 1 of the most popular types of mobile-based health apps, have been praised for their ability to provide access to patients with unmet needs. However, researchers have raised concerns about low engagement and attrition rates, which could lead to overstated efficacy.

John Torous, MD, of the department of psychiatry, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, and colleagues conducted a systematic review and meta-analysis of 3336 adult participants (median age, 39 years; range, 19 to 50 years) randomly assigned to either mobile app interventions for depression (n=1786) or control conditions (n=1550). The investigators searched several databases in May 2019 and identified 18 randomized controlled trials that fit their criteria. The trials required the use of a mobile device app for depressive symptoms and reported retention in post-treatment assessments. The intervention period ranged from 10 days to 6 months.

For participants using mobile app interventions, the pooled dropout rate was 26.2% (95% CI, 18.12-36.34) with significant heterogeneity (I2 = 93.4) and a strong indication of publication bias (Eggers t, 3.9; P <.001). When adjusting for publication bias, the rate increased to 47.8% (95% CI, 35.8-60.0). Intervention group dropout rates were higher than control group rates in studies with large samples but lower in studies offering human feedback and in-app mood monitoring.

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However, study retention rates did not differ between depression and placebo apps, cognitive behavioral therapy and non-cognitive behavioral therapy apps, mindfulness and non-mindfulness apps, clinically-diagnosed and self-reported depression, or paid and unpaid assessments.

“Study dropout in existing mental health app trials offers a standardized and practical proxy for beginning to better understand clinical engagement,” the investigators noted. The findings point to major concerns about high dropout rates and study bias in the field of research on smartphone apps for depressive symptom treatment. “Clinicians should anticipate high dropout when using apps and thus introduce them as part of a comprehensive plan with mechanisms built in to increase engagement, such as offering feedback and mood monitoring,” they concluded.

Disclosure: a study author reported funding from industry. Please see original paper for complete details.


Torous J, Lipschitz J, Ng M, Firth J. Dropout rates in clinical trials of smartphone apps for depressive symptoms: A systematic review and meta-analysis. J Affect Disord. 2020;263:413-419.