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

•Across RCTs, the dropout rate among exercisers with depression adjusted for publication bias was 18.1%.•In people with MDD, higher baseline depressive symptoms predict greater dropout.•Exercise interventions delivered by highly qualified personnel (physiotherapists and exercise physiologists) results in significantly lower dropout.•In RCT's comparing exercise to control conditions, people randomised to exercise are significantly less likely to drop out than those allocated to control arms.

ObjectiveExercise 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.MethodThree authors identified RCT's from a recent Cochrane review and conducted updated searches of major electronic databases from 01/2013 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.ResultsOverall, 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%CI=15.0-21.8%) and 17.2% (95%CI=13.5-21.7, N=31) in MDD only. In MDD participants, higher baseline depressive symptoms (β=0.0409, 95%CI=0.0809-0.0009, P=0.04) predicted greater dropout, whilst supervised interventions delivered by physiotherapists (β=−1.2029, 95%CI=−2.0967 to −0.3091, p=0.008) and exercise physiologists (β=−1.3396, 95%CI=−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%CI=0.43-0.95, p=0.02).ConclusionsExercise 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.