title: Inspiratory capacity-to-total lung capacity ratio and dyspnoea predict exercise capacity decline in COPD.
abstract: OBJECTIVE
  Exercise capacity decline is a predictor of mortality in patients with chronic obstructive pulmonary disease (COPD). Static pulmonary hyperinflation is a key determinant of exercise performance, but its effect on the longitudinal decline in exercise capacity remains unknown. We aimed to study the relationship between the inspiratory capacity-to-total lung capacity (IC/TLC) ratio and exercise capacity decline in COPD.
  
  
  METHODS
  We measured IC/TLC and other relevant clinical and functional variables in 342 clinically stable patients with COPD. The 6-min walk distance (6MWD) was determined at recruitment and after a mean ± SD of 1.7 ± 0.3 years. The annual rate of change in 6MWD was calculated. Multiple imputation to account for losses during follow up was implemented, and multivariate regression was used to analyze predictive factors of 6MWD decline.
  
  
  RESULTS
  Mean decline rate in the 6MWD was 21.9 ± 34.1 m/year. In the bivariate analysis, patients with lower levels of IC/TLC had greater 6MWD decline (-27.4 ± 42.5, -24.9 ± 36.5 and -13.4 ± 39.9 m/year in the first, second and third tertile of IC/TLC, respectively; P-for-trend = 0.018). From other potential risk factors considered, dyspnoea, health status, serum C-reactive protein and Borg dyspnoea score at the end of the exercise test were related to exercise capacity decline. In the multivariate regression model, only IC/TLC (β = 0.7 m/year per each percentage unit of IC/TLC; P = 0.007) and dyspnoea (mMRC ≥ 2) (β = -14.6 m/year; P = 0.013) were associated with the annual rate of 6MWD change.
  
  
  CONCLUSIONS
  IC/TLC and dyspnoea in clinically stable patients with COPD predict their exercise capacity decline and may help to guide early therapeutic interventions.
authors.affiliation: Department of Pneumology, Hospital Universitari Vall d'Hebron, Barcelona, Spain.|Departament de Medicina, Universitat Autònoma de Barcelona, Barcelona, Spain.|CIBER de Enfermedades Respiratorias (CIBERES), Barcelona, Spain.
authors.forename: Maria A
authors.initials: MA
authors.lastname: Ramon
authors.affiliation: Department of Pneumology, Hospital Universitari Vall d'Hebron, Barcelona, Spain.|Departament de Medicina, Universitat Autònoma de Barcelona, Barcelona, Spain.|CIBER de Enfermedades Respiratorias (CIBERES), Barcelona, Spain.
authors.forename: Jaume
authors.initials: J
authors.lastname: Ferrer
authors.affiliation: Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Spain.|CIBER Epidemiología y Salud Pública (CIBERESP), Barcelona, Spain.|Universitat Pompeu Fabra (UPF), Barcelona, Spain.
authors.forename: Elena
authors.initials: E
authors.lastname: Gimeno-Santos
authors.affiliation: Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Spain.|CIBER Epidemiología y Salud Pública (CIBERESP), Barcelona, Spain.|Universitat Pompeu Fabra (UPF), Barcelona, Spain.
authors.forename: David
authors.initials: D
authors.lastname: Donaire-Gonzalez
authors.affiliation: Department of Pneumology, Hospital Universitari Vall d'Hebron, Barcelona, Spain.|Departament de Medicina, Universitat Autònoma de Barcelona, Barcelona, Spain.|CIBER de Enfermedades Respiratorias (CIBERES), Barcelona, Spain.
authors.forename: Esther
authors.initials: E
authors.lastname: Rodríguez
authors.affiliation: CIBER de Enfermedades Respiratorias (CIBERES), Barcelona, Spain.|Universitat Pompeu Fabra (UPF), Barcelona, Spain.|IMIM (Hospital del Mar Medical Research Institute), Barcelona, Spain.|Department of Pneumology, Hospital del Mar, Barcelona, Spain.
authors.forename: Eva
authors.initials: E
authors.lastname: Balcells
authors.affiliation: Centre for Research in Environmental Epidemiology (CREAL), 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: Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Spain.|CIBER Epidemiología y Salud Pública (CIBERESP), Barcelona, Spain.|Universitat Pompeu Fabra (UPF), Barcelona, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Benet
authors.affiliation: Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Spain.|CIBER Epidemiología y Salud Pública (CIBERESP), Barcelona, Spain.|Universitat Pompeu Fabra (UPF), Barcelona, Spain.
authors.forename: Stefano
authors.initials: S
authors.lastname: Guerra
authors.affiliation: Department of Pneumology, Hospital Universitari Son Espases, Institut d'Investigació Sanitària de Palma (IdISPa), Palma Mallorca, Spain.
authors.forename: Jaume
authors.initials: J
authors.lastname: Sauleda
authors.affiliation: CIBER de Enfermedades Respiratorias (CIBERES), Barcelona, Spain.|Universitat Pompeu Fabra (UPF), Barcelona, Spain.|IMIM (Hospital del Mar Medical Research Institute), Barcelona, Spain.|Department of Pneumology, Hospital del Mar, Barcelona, Spain.|Department of Pneumology, Hospital de Sabadell, Corporació Parc Taulí, Sabadell, Spain.
authors.forename: Antoni
authors.initials: A
authors.lastname: Ferrer
authors.affiliation: Department of Pneumology, Hospital Universitari de Bellvitge, Barcelona, Spain.|Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), Barcelona, Spain.
authors.forename: Eva
authors.initials: E
authors.lastname: Farrero
authors.affiliation: CIBER de Enfermedades Respiratorias (CIBERES), Barcelona, Spain.|Universitat Pompeu Fabra (UPF), Barcelona, Spain.|IMIM (Hospital del Mar Medical Research Institute), Barcelona, Spain.|Department of Pneumology, Hospital del Mar, Barcelona, Spain.
authors.forename: Joaquim
authors.initials: J
authors.lastname: Gea
authors.affiliation: CIBER de Enfermedades Respiratorias (CIBERES), Barcelona, Spain.|Servei de Pneumologia (Thorax Institute), Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Universitat de Barcelona, Barcelona, Spain.
authors.forename: Joan A
authors.initials: JA
authors.lastname: Barberà
authors.affiliation: CIBER de Enfermedades Respiratorias (CIBERES), Barcelona, Spain.|Servei de Pneumologia (Thorax Institute), Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Universitat de Barcelona, Barcelona, Spain.
authors.forename: Alvar
authors.initials: A
authors.lastname: Agustí
authors.affiliation: CIBER de Enfermedades Respiratorias (CIBERES), Barcelona, Spain.|Servei de Pneumologia (Thorax Institute), Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Universitat de Barcelona, Barcelona, Spain.
authors.forename: Robert
authors.initials: R
authors.lastname: Rodriguez-Roisin
authors.affiliation: Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Spain.|CIBER Epidemiología y Salud Pública (CIBERESP), Barcelona, Spain.|Universitat Pompeu Fabra (UPF), Barcelona, Spain.|IMIM (Hospital del Mar Medical Research Institute), Barcelona, Spain.
authors.forename: Josep M
authors.identifier: http://orcid.org/0000-0002-4736-8529
authors.initials: JM
authors.lastname: Antó
authors.affiliation: Centre 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.identifier: http://orcid.org/0000-0002-7097-4586
authors.initials: J
authors.lastname: Garcia-Aymerich
mesh_terms: D000368:Aged; D004417:Dyspnea / Q000209:etiology / Q000503:physiopathology*; D005080:Exercise Test; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D006801:Humans; D007320:Inspiratory Capacity / Q000502:physiology*; D008168:Lung / Q000503:physiopathology*; D008297:Male; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000503:physiopathology*; D014109:Total Lung Capacity / Q000502:physiology*
keywords: 6-min walk distance; chronic obstructive pulmonary disease; cohort study; disease progression; exercise capacity