title: Three-year follow-up of Interleukin 6 and C-reactive protein in chronic obstructive pulmonary disease.
abstract: BACKGROUND
  Past studies have shown that mean values of Interleukin-6 (IL-6) and C-reactive protein (CRP) do not change significantly in COPD patients over a one-year period. However, longer period follow-up studies are still lacking. Thus, the aim of this study is to evaluate plasma CRP and IL-6 concentration over three years in COPD patients and to test the association between these inflammatory mediators and disease outcome markers.
  
  
  METHODS
  A cohort of 77 outpatients with stable COPD was evaluated at baseline, and 53 (mean FEV1, 56% predicted) were included in the prospective study. We evaluated Interleukin-6 (IL-6), C-reactive protein (CRP), six-minute walking distance (6MWD), and body mass index (BMI) at baseline and after three years. Plasma concentration of IL-6 was measured by high sensitivity ELISA, and CRP was obtained by high sensitivity particle-enhanced immunonephelometry.
  
  
  RESULTS
  IL-6 increased significantly after 3 years compared to baseline measurements [0.8 (0.5-1.3) vs 2.4 (1.3-4.4) pg/ml; p < 0.001] and was associated with worse 6MWD performance. In the Cox regression, increased IL-6 at baseline was associated with mortality [Hazard Ratio (95% CI) = 2.68 (0.13, 1.84); p = 0.02]. CRP mean values did not change [5 (1.6-7.9) vs 4.7 (1.7-10) pg/L; p = 0.84], although eleven patients (21%) presented with changes >3 mg/L in CRP after 3 years.
  
  
  CONCLUSIONS
  The systemic inflammatory process, evaluated by IL-6, seems to be persistent, progressive and associated with mortality and worse physical performance in COPD patients.
  
  
  BACKGROUND
  No.:NCT00605540.
authors: Faculdade de Medicina de Botucatu, Univ Estadual Paulista, Unesp, Disciplina de Pneumologia, Botucatu, São Paulo, Brazil. renataferrarifisio@gmail.com
authors: Renata
authors: R
authors: Ferrari
authors: Suzana E
authors: SE
authors: Tanni
authors: Laura M O
authors: LM
authors: Caram
authors: Corina
authors: C
authors: Corrêa
authors: Camila R
authors: CR
authors: Corrêa
authors: Irma
authors: I
authors: Godoy
mesh_terms: D015415:Biomarkers / Q000097:blood; D001938:Brazil / Q000453:epidemiology; D002097:C-Reactive Protein / Q000032:analysis*; D005080:Exercise Test / Q000706:statistics & numerical data*; D017079:Exercise Tolerance; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015850:Interleukin-6 / Q000097:blood*; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood* / Q000175:diagnosis / Q000401:mortality*; D012307:Risk Factors; D016019:Survival Analysis; D015996:Survival Rate
chemical_list: D015415:Biomarkers; C508600:IL6 protein, human; D015850:Interleukin-6; D002097:C-Reactive Protein