Who drops out? Characteristics associated with dropout in a low-threshold physical activity intervention for people with mental illness – an exploratory analysis

Objective Exercise interventions in people with mental disorder often face high dropout rates. While previous research has mainly focused on structural and motivational barriers, less is known about individual patient characteristics. This study aimed to identify characteristics associated with dropout in an exercise intervention for people with mental illness.Methods In this longitudinal, rater-blind randomised controlled study, 82 adult psychiatric patients were assigned to a self-directed low-threshold exercise intervention. Sociodemographics, clinical, and physical health characteristics were assessed at baseline and three-month follow-up. Physical activity was measured using accelerometry. Differences between dropouts and non-dropouts were analysed using group comparisons and multivariate analyses.Results 57 participants completed the intervention, while 25 dropped out. Dropouts had lower educational levels, were more likely to smoke or use cannabis, reported higher depressive symptoms, and were more often male. All outpatients completed the intervention, whereas dropouts occurred exclusively among inpatients.Conclusions Dropout was associated with individual factors, including sex, education, substance use, symptom severity, and treatment setting. Low-threshold programmes remain important to reach broad patient groups while conserving resources. Identifying individuals needing additional support and implementing targeted strategies, such as coaching, digital guidance, and structured support during care transitions, may improve adherence in personalised psychiatric treatment.