title: Determinants and outcomes of physical activity in patients with COPD: a systematic review.
abstract: BACKGROUND
  The relationship between physical activity, disease severity, health status and prognosis in patients with COPD has not been systematically assessed. Our aim was to identify and summarise studies assessing associations between physical activity and its determinants and/or outcomes in patients with COPD and to develop a conceptual model for physical activity in COPD.
  
  
  METHODS
  We conducted a systematic search of four databases (Medline, Embase, CINAHL and Psychinfo) prior to November 2012. Teams of two reviewers independently selected articles, extracted data and used the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) to assess quality of evidence.
  
  
  RESULTS
  86 studies were included: 59 were focused on determinants, 23 on outcomes and 4 on both. Hyperinflation, exercise capacity, dyspnoea, previous exacerbations, gas exchange, systemic inflammation, quality of life and self-efficacy were consistently related to physical activity, but often based on cross-sectional studies and low-quality evidence. Results from studies of pharmacological and non-pharmacological treatments were inconsistent and the quality of evidence was low to very low. As outcomes, COPD exacerbations and mortality were consistently associated with low levels of physical activity based on moderate quality evidence. Physical activity was associated with other outcomes such as dyspnoea, health-related quality of life, exercise capacity and FEV1 but based on cross-sectional studies and low to very low quality evidence.
  
  
  CONCLUSIONS
  Physical activity level in COPD is consistently associated with mortality and exacerbations, but there is poor evidence about determinants of physical activity, including the impact of treatment.
authors.affiliation: Center for Research in Environmental Epidemiology (CREAL), Barcelona, Spain CIBER Epidemiología y Salud Pública (CIBERESP), Barcelona, Spain Universitat Pompeu Fabra (UPF), Barcelona, Spain FCS Blanquerna, Research Group in Physiotherapy (GReFis), Universitat Ramon Llull, Barcelona, Spain.
authors.forename: Elena
authors.initials: E
authors.lastname: Gimeno-Santos
authors.affiliation: Institute of Social and Preventive Medicine, University of Zurich, Zurich, Switzerland Institute of General Practice and Health Services Research, University of Zurich, Zurich, Switzerland.
authors.forename: Anja
authors.initials: A
authors.lastname: Frei
authors.affiliation: Institute of General Practice and Health Services Research, University of Zurich, Zurich, Switzerland.
authors.forename: Claudia
authors.initials: C
authors.lastname: Steurer-Stey
authors.affiliation: Center for Research in Environmental Epidemiology (CREAL), Barcelona, Spain CIBER Epidemiología y Salud Pública (CIBERESP), Barcelona, Spain Section of Nutrition and Metabolism, International Agency for Research on Cancer, Lyon, France.
authors.forename: Jordi
authors.initials: J
authors.lastname: de Batlle
authors.affiliation: ELEGI/Colt Laboratory, UoE/MRC Centre for Inflammation Research, University of Edinburgh, Edinburgh, UK.
authors.forename: Roberto A
authors.initials: RA
authors.lastname: Rabinovich
authors.affiliation: NIHR Respiratory Biomedical Research Unit of the Royal Brompton and Harefield NHS Foundation Trust and Imperial College London, London, UK.
authors.forename: Yogini
authors.initials: Y
authors.lastname: Raste
authors.affiliation: NIHR Respiratory Biomedical Research Unit of the Royal Brompton and Harefield NHS Foundation Trust and Imperial College London, London, UK.
authors.forename: Nicholas S
authors.initials: NS
authors.lastname: Hopkinson
authors.affiliation: NIHR Respiratory Biomedical Research Unit of the Royal Brompton and Harefield NHS Foundation Trust and Imperial College London, London, UK.
authors.forename: Michael I
authors.initials: MI
authors.lastname: Polkey
authors.affiliation: Respiratory Division, Katholieke University of Leuven, Leuven, Belgium.
authors.forename: Hans
authors.initials: H
authors.lastname: van Remoortel
authors.affiliation: Respiratory Division, Katholieke University of Leuven, Leuven, Belgium.
authors.forename: Thierry
authors.initials: T
authors.lastname: Troosters
authors.affiliation: Respiratory Department, Novartis, Basel, Switzerland.
authors.forename: Karoly
authors.initials: K
authors.lastname: Kulich
authors.affiliation: R&D, AstraZeneca, Södertälje, Sweden.
authors.forename: Niklas
authors.initials: N
authors.lastname: Karlsson
authors.affiliation: Institute of Social and Preventive Medicine, University of Zurich, Zurich, Switzerland Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, USA.
authors.forename: Milo A
authors.initials: MA
authors.lastname: Puhan
authors.affiliation: Center for Research in Environmental Epidemiology (CREAL), Barcelona, Spain CIBER Epidemiología y Salud Pública (CIBERESP), Barcelona, Spain Universitat Pompeu Fabra (UPF), Barcelona, Spain.
authors.forename: Judith
authors.initials: J
authors.lastname: Garcia-Aymerich
mesh_terms: D006801:Humans; D009043:Motor Activity; D011379:Prognosis; D029424:Pulmonary Disease, Chronic Obstructive / Q000188:drug therapy / Q000401:mortality / Q000503:physiopathology*; D011788:Quality of Life
keywords: COPD Exacerbations; COPD epidemiology; Exercise