title: Dropout from exercise randomized controlled trials among people with depression: A meta-analysis and meta regression.
abstract: 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.
  
  
  METHODS
  Three 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.
  
  
  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%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).
  
  
  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.
authors.affiliation: Physiotherapy Department, South London and Maudsley NHS Foundation Trust, Denmark Hill, London SE5 8AZ, United Kingdom; Health Service and Population Research Department, Institute of Psychiatry, King's College London, De Crespigny Park, Box SE5 8 AF, London, United Kingdom. Electronic address: brendon.stubbs@kcl.ac.uk.
authors.forename: Brendon
authors.initials: B
authors.lastname: Stubbs
authors.affiliation: KU Leuven - University of Leuven Department of Rehabilitation Sciences, Leuven, Belgium; KU Leuven - University of Leuven, Z. org Leuven, Campus Kortenberg, Kortenberg, Belgium.
authors.forename: Davy
authors.initials: D
authors.lastname: Vancampfort
authors.affiliation: School of Psychiatry, University of New South Wales, Sydney, Australia.
authors.forename: Simon
authors.initials: S
authors.lastname: Rosenbaum
authors.affiliation: School of Psychiatry, University of New South Wales, Sydney, Australia.
authors.forename: Philip B
authors.initials: PB
authors.lastname: Ward
authors.affiliation: School of Public Health, Charles Perkins Centre, University of Sydney, Sydney, Australia.
authors.forename: Justin
authors.initials: J
authors.lastname: Richards
authors.affiliation: School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham B15 2TT, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Soundy
authors.affiliation: Department of Medicine - DIMED, Geriatrics Section, University of Padova, Padova, Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Veronese
authors.affiliation: Department of Neurosciences, University of Padova, Padova, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Solmi
authors.affiliation: Hospital de Clinicas de Porto Alegre, Porto Alegre, Brazil; Programade Pós Graduação em Ciências Médicas: Psiquiatria, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Felipe B
authors.initials: FB
authors.lastname: Schuch
mesh_terms: D003863:Depression / Q000628:therapy*; D003865:Major Depressive Disorder / Q000628:therapy*; D005081:Exercise Therapy; D006801:Humans; D010352:Patient Dropouts / Q000706:statistics & numerical data*; D015995:Prevalence; D016032:Randomized Controlled Trials as Topic / Q000706:statistics & numerical data*
keywords: Depression; Dropout; Exercise; Physical activity