title: Systemic inflammation in chronic obstructive pulmonary disease: a population-based study.
abstract: BACKGROUND
  Elevated circulating levels of several inflammatory biomarkers have been described in selected patient populations with COPD, although less is known about their population-based distribution. The aims of this study were to compare the levels of several systemic biomarkers between stable COPD patients and healthy subjects from a population-based sample, and to assess their distribution according to clinical variables.
  
  
  METHODS
  This is a cross-sectional study design of participants in the EPI-SCAN study (40-80 years of age). Subjects with any other condition associated with an inflammatory process were excluded. COPD was defined as a post-bronchodilator FEV1/FVC < 0.70. The reference group was made of non-COPD subjects without respiratory symptoms, associated diseases or prescription of medication. Subjects were evaluated with quality-of-life questionnaires, spirometry and 6-minute walk tests. Serum C-reactive protein (CRP), tumor necrosis factor (TNF)-alpha, interleukins (IL-6 and IL-8), alpha1-antitrypsin, fibrinogen, albumin and nitrites/nitrates (NOx) were measured.
  
  
  RESULTS
  We compared 324 COPD patients and 110 reference subjects. After adjusting for gender, age, BMI and tobacco consumption, COPD patients showed higher levels of CRP (0.477 +/- 0.023 vs. 0.376 +/- 0.041 log mg/L, p = 0.049), TNF-alpha (13.12 +/- 0.59 vs. 10.47 +/- 1.06 pg/mL, p = 0.033), IL-8 (7.56 +/- 0.63 vs. 3.57 +/- 1.13 pg/ml; p = 0.033) and NOx (1.42 +/- 0.01 vs. 1.36 +/- 0.02 log nmol/l; p = 0.048) than controls. In COPD patients, serum concentrations of some biomarkers were related to severity and their exercise tolerance was related to serum concentrations of CRP, IL-6, IL-8, fibrinogen and albumin.
  
  
  CONCLUSIONS
  Our results provide population-based evidence that COPD is independently associated with low-grade systemic inflammation, with a different inflammatory pattern than that observed in healthy subjects.
authors.affiliation: Pneumology Service, Hospital Universitario La Paz, IdiPAZ, Madrid, Spain. fgr01m@gmail.com
authors.forename: Francisco
authors.initials: F
authors.lastname: Garcia-Rio
authors.forename: Marc
authors.initials: M
authors.lastname: Miravitlles
authors.forename: Joan B
authors.initials: JB
authors.lastname: Soriano
authors.forename: Luis
authors.initials: L
authors.lastname: Muñoz
authors.forename: Enric
authors.initials: E
authors.lastname: Duran-Tauleria
authors.forename: Guadalupe
authors.initials: G
authors.lastname: Sánchez
authors.forename: Víctor
authors.initials: V
authors.lastname: Sobradillo
authors.forename: Julio
authors.initials: J
authors.lastname: Ancochea
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005080:Exercise Test; D017079:Exercise Tolerance; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D007249:Inflammation / Q000453:epidemiology* / Q000276:immunology; D018836:Inflammation Mediators / Q000097:blood*; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000453:epidemiology* / Q000276:immunology / Q000503:physiopathology; D011788:Quality of Life; D012720:Severity of Illness Index; D013030:Spain / Q000453:epidemiology; D011795:Surveys and Questionnaires; D015854:Up-Regulation; D014797:Vital Capacity
chemical_list: D015415:Biomarkers; D018836:Inflammation Mediators