title: Ectopic fat accumulation in patients with COPD: an ECLIPSE substudy.
abstract: BACKGROUND
  Obesity is increasingly associated with COPD, but little is known about the prevalence of ectopic fat accumulation in COPD and whether this can possibly be associated with poor clinical outcomes and comorbidities. The Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints (ECLIPSE) substudy tested the hypothesis that COPD is associated with increased ectopic fat accumulation and that this would be associated with COPD-related outcomes and comorbidities.
  
  
  METHODS
  Computed tomography (CT) images of the thorax obtained in ECLIPSE were used to quantify ectopic fat accumulation at L2-L3 (eg, cross-sectional area [CSA] of visceral adipose tissue [VAT] and muscle tissue [MT] attenuation, a reflection of muscle fat infiltration) and CSA of MT. A dose-response relationship between CSA of VAT, MT attenuation and CSA of MT and COPD-related outcomes (6-minute walking distance [6MWD], exacerbation rate, quality of life, and forced expiratory volume in 1 second [FEV1] decline) was addressed with the Cochran-Armitage trend test. Regression models were used to investigate possible relationships between CT body composition indices and comorbidities.
  
  
  RESULTS
  From the entire ECLIPSE cohort, we identified 585 subjects with valid CT images at L2-L3 to assess body composition. CSA of VAT was increased (P<0.0001) and MT attenuation was reduced (indicating more muscle fat accumulation) in patients with COPD (P<0.002). Progressively increasing CSA of VAT was not associated with adverse clinical outcomes. The probability of exhibiting low 6MWD and accelerated FEV1decline increased with progressively decreasing MT attenuation and CSA of MT. In COPD, the probability of having diabetes (P=0.024) and gastroesophageal reflux (P=0.0048) at baseline increased in parallel with VAT accumulation, while the predicted MT attenuation increased the probability of cardiovascular comorbidities (P=0.042). Body composition parameters did not correlate with coronary artery scores or with survival.
  
  
  CONCLUSIONS
  Ectopic fat accumulation is increased in COPD, and this was associated with relevant clinical outcomes and comorbidities.
authors.affiliation: Research Centre, Institut universitaire de cardiologie et de pneumologie de Québec, Université Laval, Québec, QC.
authors.forename: Mickaël
authors.initials: M
authors.lastname: Martin
authors.affiliation: Research Centre, Institut universitaire de cardiologie et de pneumologie de Québec, Université Laval, Québec, QC.
authors.forename: Natalie
authors.initials: N
authors.lastname: Almeras
authors.affiliation: Research Centre, Institut universitaire de cardiologie et de pneumologie de Québec, Université Laval, Québec, QC.
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Després
authors.affiliation: Department of Radiology, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Harvey O
authors.initials: HO
authors.lastname: Coxson
authors.affiliation: Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: George R
authors.initials: GR
authors.lastname: Washko
authors.affiliation: Hypoxia Pathophysiology Laboratory, Grenoble University Hospital, Grenoble, France.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Vivodtzev
authors.affiliation: Department of Respiratory Medicine, Maastricht University Medical Center, Maastricht.
authors.forename: Emiel Fm
authors.initials: EF
authors.lastname: Wouters
authors.affiliation: Research and Development, CIRO, Horn, the Netherlands.
authors.forename: Erica
authors.initials: E
authors.lastname: Rutten
authors.affiliation: Department of Respiratory Medicine, University of Edinburgh.
authors.forename: Michelle C
authors.initials: MC
authors.lastname: Williams
authors.affiliation: Department of Radiology, Royal Infirmary of Edinburgh, Edinburgh, UK.
authors.forename: John T
authors.initials: JT
authors.lastname: Murchison
authors.affiliation: Department of Respiratory Medicine, University of Edinburgh.
authors.forename: William
authors.initials: W
authors.lastname: MacNee
authors.affiliation: Department of Radiology, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Don D
authors.initials: DD
authors.lastname: Sin
authors.affiliation: Research Centre, Institut universitaire de cardiologie et de pneumologie de Québec, Université Laval, Québec, QC.
authors.forename: François
authors.initials: F
authors.lastname: Maltais
mesh_terms: D000009:Abdominal Muscles / Q000000981:diagnostic imaging / Q000503:physiopathology*; D050154:Adiposity; D000368:Aged; D016022:Case-Control Studies; D015897:Comorbidity; D018450:Disease Progression; D017079:Exercise Tolerance; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D050152:Intra-Abdominal Fat / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008137:Longitudinal Studies; D008168:Lung / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D029424:Pulmonary Disease, Chronic Obstructive / Q000000981:diagnostic imaging / Q000503:physiopathology*; D011788:Quality of Life; D013909:Thorax; D014057:Tomography, X-Ray Computed; D000070857:Walk Test
keywords: abdominal adiposity; metabolic syndrome; muscle; obesity