title: Self-reported influenza vaccination and protective serum antibody titers in a cohort of COPD patients.
abstract: COPD patients are advised vaccination against seasonal influenza, yet few studies have evaluated the protective antibody titers obtained in this patient group.
  
  
  
  1) To describe protective titers in COPD patients who self-reported influenza vaccination compared with vaccinated subjects without COPD and unvaccinated COPD patients, 2) analyze whether clinical parameters predicted influenza-specific antibody titers, and 3) whether antibody titers to influenza A at baseline could predict exacerbation risk or 5 years all-cause mortality.
  
  
  
  Influenza A (H1N1 and H3N2) titers were measured by haemagglutination inhibition assay in serum from 432 COPD patients and 77 controls in the Bergen COPD Cohort Study, at yearly visits between 2006/09. Titers of 40 or above were considered protective. We examined the variables sex, age, body composition, smoking, GOLD stage, yearly exacerbations, inhaled steroids, and Charlson score as predictive of titers, both univariately and in a multivariable model estimated by generalized estimating equations. The exacerbation incidence rate ratios and mortality hazard ratios were assessed by negative binominal and cox regression models respectively.
  
  
  
  At baseline, 59% of COPD patients reported influenza vaccination during the last season. Levels of predictive titers varied considerably each season, but trended lower in COPD patients compared with controls. Neither sex, age, body composition, smoking, comorbidities, GOLD stage nor use of inhaled steroids consistently predicted titers. Having high titers at baseline did not impact later risk for exacerbations, but seemed to be associated with higher all-cause mortality, even after adjustment for COPD disease characteristics.
  
  
  
  Vaccination coverage for influenza is imperfect for COPD patients in Norway, and there is a concern that immunization is suboptimal.
authors.affiliation: Dept. of Clinical Science, Faculty of Medicine and Dentistry, University of Bergen, Norway; Dept. of Thoracic Medicine, Haukeland University Hospital, Bergen, Norway. Electronic address: tomas.eagan@uib.no.
authors.forename: T M
authors.initials: TM
authors.lastname: Eagan
authors.affiliation: Dept. of Clinical Science, Faculty of Medicine and Dentistry, University of Bergen, Norway.
authors.forename: J A
authors.initials: JA
authors.lastname: Hardie
authors.affiliation: Dept. of Clinical Science, Faculty of Medicine and Dentistry, University of Bergen, Norway.
authors.forename: Å
authors.initials: Å
authors.lastname: Jul-Larsen
authors.affiliation: Dept. of Thoracic Medicine, Haukeland University Hospital, Bergen, Norway.
authors.forename: T B
authors.initials: TB
authors.lastname: Grydeland
authors.affiliation: Dept. of Clinical Science, Faculty of Medicine and Dentistry, University of Bergen, Norway.
authors.forename: P S
authors.initials: PS
authors.lastname: Bakke
authors.affiliation: Dept. of Clinical Science, Faculty of Medicine and Dentistry, University of Bergen, Norway; Dept of Research and Development, Haukeland University Hospital, Bergen, Norway; Jebsen Centre for Influenza Vaccine Research, University of Bergen, Bergen, Norway.
authors.forename: R J
authors.initials: RJ
authors.lastname: Cox
mesh_terms: D000328:Adult; D000368:Aged; D000914:Antibodies, Viral / Q000097:blood; D015331:Cohort Studies; D015897:Comorbidity; D005260:Female; D006385:Hemagglutination Inhibition Tests / Q000379:methods; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology; D053122:Influenza A Virus, H3N2 Subtype / Q000276:immunology; D007252:Influenza Vaccines / Q000008:administration & dosage* / Q000276:immunology; D007251:Influenza, Human / Q000453:epidemiology / Q000517:prevention & control* / Q000628:therapy / Q000821:virology; D008297:Male; D008875:Middle Aged; D009026:Mortality; D009664:Norway / Q000453:epidemiology; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis / Q000276:immunology* / Q000503:physiopathology; D012621:Seasons; D057566:Self Report; D012907:Smoking / Q000276:immunology; D014611:Vaccination / Q000009:adverse effects / Q000379:methods*
chemical_list: D000914:Antibodies, Viral; D007252:Influenza Vaccines
keywords: COPD; Influenza; Vaccination