Dropout from exercise randomized controlled trials among people with anxiety and stress-related disorders: A meta-analysis and meta-regression

Objective: Exercise has established efficacy in people with anxiety and stress-related disorders. Dropouts from randomized controlled trials (RCT's) pose a threat to the validity of the evidence, with dropout rates varying across studies. We conducted a meta-analysis to investigate the prevalence and predictors of dropout rates among adults with anxiety and stress-related disorders participating in exercise RCT's. Methods: Two authors searched major electronic databases up to 07/2020. We included RCT's of exercise interventions in people with anxiety and stress-related disorders that reported dropout rates. A random effects meta-analysis and meta-regression were conducted. Results: Fourteen RCT's involving 16 exercise interventions (n=369, mean age 20.7 to 67.7years; 38.4% male) were included. The trim-and-fill-adjusted prevalence of dropout across all studies was 22.4% (95%CI = 15.0% to 32.0%). Applying controlled motivation strategies (P<0.001) predicted higher dropout. Supervision during all sessions and by an expert in exercise prescription and applying autonomous motivation strategies predicted lower dropout (all P<0.001). Dropout was similar in exercise versus control conditions (OR = 0.84, 95%CI = 0.54 to 1.29, p = 0.42, I2 = 0%; N=16). Limitations: Potentially important moderators of dropout, such as the severity of mental health symptoms and illness duration were insufficiently available. Conclusions: Exercise is well tolerated by people with anxiety and stress-related disorders and drop out in RCT's is comparable to control conditions. Thus, exercise is a feasible treatment, in particular when autonomous motivation strategies are included and when the intervention is delivered by healthcare professionals with expertise in exercise prescription.