title: Different COPD disease characteristics are related to different outcomes in the 6-minute walk test.
abstract: BACKGROUND
  Chronic obstructive pulmonary disease (COPD) can lead to severe disability as the disease advances. The 6-minute walk test (6MWT) is commonly used to measure functional capacity in COPD patients and has three potential outcomes; walking distance, oxygen desaturation, and self-perceived dyspnea assessed by the Borg scale, all reflecting different aspects of COPD. The aim of this study was to identify predictors of all 3 outcomes of 6MWT in patients with COPD.
  
  
  METHODS
  370 COPD patients, aged 40-75 yrs, were included from the first phase of the Bergen COPD cohort study. They were examined with spirometry, bioelectrical impedance measurements, 6MWT, Center for Epidemiologic Studies of Depression (CES-D) Scale, Medical Research Council (MRC) dyspnea scale, Charlson index for co-morbidities, self-reported physical activity questionnaire, plasma levels of C-reactive protein (CRP) and arterial blood gases.
  
  
  RESULTS
  Significant predictors in the multivariate analyses were sex, age, FEV(1) in % predicted, symptoms of dyspnea (MRC), co-morbidities (Charlson Index) and self-reported physical activity for walking distance, FEV(1) in % predicted and PaO(2) for oxygen desaturation, and body composition, smoking and co-morbidities for self-perceived dyspnea assessed by the Borg scale.
  
  
  CONCLUSIONS
  Several COPD characteristics have predictive value for the 6MWT, and some COPD characteristics are more strongly related to specific 6MWT outcomes than others.
authors.affiliation: Centre for Clinical Research, Haukeland University Hospital, Bergen, Norway. marie.johanne.waatevik@helse-bergen.no
authors.forename: Marie
authors.initials: M
authors.lastname: Waatevik
authors.forename: Ane
authors.initials: A
authors.lastname: Johannessen
authors.forename: Jon A
authors.initials: JA
authors.lastname: Hardie
authors.forename: Jan Magnus
authors.initials: JM
authors.lastname: Bjordal
authors.forename: Pål
authors.initials: P
authors.lastname: Aukrust
authors.forename: Per S
authors.initials: PS
authors.lastname: Bakke
authors.forename: Tomas M L
authors.initials: TM
authors.lastname: Eagan
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D002097:C-Reactive Protein / Q000032:analysis; D015331:Cohort Studies; D004417:Dyspnea; D005080:Exercise Test / Q000706:statistics & numerical data*; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D008875:Middle Aged; D010092:Oximetry; D010100:Oxygen / Q000097:blood; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology*; D012129:Respiratory Function Tests; D012307:Risk Factors; D012737:Sex Factors; D012907:Smoking; D016138:Walking
chemical_list: D002097:C-Reactive Protein; D010100:Oxygen