Dropout from exercise randomized controlled trials among people with depression: A meta-analysis and meta regression

Objective: Exercise has established efficacy in improving depressive symptoms. Dropouts from randomized controlled trials (RCT's) pose a threat to the validity of this evidence base, with dropout rates varying across studies. We conducted a systematic review and meta-analysis to investigate the prevalence and predictors of dropout rates among adults with depression participating in exercise RCT's. Method: Three authors identified RCT's from a recent Cochrane review and conducted updated searches of major electronic databases from 0112013 to 08/2015. We included RCT's of exercise interventions in people with depression (including major depressive disorder (MDD) and depressive symptoms) that reported dropout rates. A random effects meta-analysis and meta regression were conducted. Results: Overall, 40 RCT's were included reporting dropout rates across 52 exercise interventions including 1720 people with depression (49.1 years (range=19-76 years), 72% female (range= 0-100)). The trim and fill adjusted prevalence of dropout across all studies was 18.1% (95%Cl=15.0-21.8%) and 17.2% (95%Cl=13.5-21.7, N=31) in MDD only. In MDD participants, higher baseline depressive symptoms (beta=0.0409, 95%Cl=0.0809-0.0009, P=0.04) predicted greater dropout, whilst supervised interventions delivered by physiotherapists (beta= 1.2029, 95%Cl= 2.0967 to 0.3091, p = 0.008) and exercise physiologists (beta= 1.3396, 95%Cl= 2.4478 to 0.2313, p =0.01) predicted lower dropout. A comparative meta-analysis (N=29) established dropout was lower in exercise than control conditions (OR=0.642, 95%Cl=0.43-0.95, p =0.02). Conclusions: Exercise is well tolerated by people with depression and drop out in RCT's is lower than control conditions. Thus, exercise is a feasible treatment, in particular when delivered by healthcare professionals with specific training in exercise prescription. (C) 2015 Elsevier BY. All rights reserved.