title: Influenza vaccine for patients with chronic obstructive pulmonary disease.
abstract: BACKGROUND
  Influenza vaccinations are currently recommended in the care of people with COPD, but these recommendations are based largely on evidence from observational studies with very few randomised controlled trials (RCTs) reported. Influenza infection causes excess morbidity and mortality in COPD patients but there is also the potential for influenza vaccination to cause adverse effects or not to be cost effective.
  
  
  OBJECTIVE
  To evaluate the evidence from RCTs for a treatment effect of influenza vaccination in COPD subjects. Outcomes of interest were exacerbation rates, hospitalisations, mortality, lung function and adverse effects.
  
  
  METHODS
  We searched the Cochrane Airways Group trials register and reference lists of articles. References were also provided by a number of drug companies we contacted.
  
  
  METHODS
  RCTs that compared live or inactivated virus vaccines with placebo, either alone or with another vaccine in persons with COPD. Studies of people with asthma were excluded.
  
  
  METHODS
  Two reviewers extracted data. All entries were double checked. Study authors and drug companies were contacted for missing information.
  
  
  RESULTS
  Nine trials were included but only four of these were specifically performed in COPD patients. The others were conducted on elderly and high-risk individuals, some of whom had chronic lung disease. In one study of inactivated vaccine in COPD patients there was a significant reduction in the total number of exacerbations per vaccinated subject compared with those who received placebo (weighted mean difference (WMD) -0.45, 95% confidence interval -0.75 to -0.15, p = 0.004). This difference was mainly due to the reduction in exacerbations occurring after 3 weeks (WMD -0.44, (95% CI -0.68 to -0.20, p<0.001). The number of patients experiencing late exacerbations was also significantly less (OR= 0.13, 95%CI 0.04 to 0.45, p=0.002). There was no evidence of an effect of intranasal live attenuated virus when this was added to inactivated intramuscular vaccination. In studies in elderly patients (only a minority of whom had COPD), there was a significant increase in the occurrence of local adverse reactions in vaccinees, but the effects were generally mild and transient.
  
  
  CONCLUSIONS
  It appears, from the limited number of studies performed, that inactivated vaccine may reduce exacerbations in COPD patients. The size of effect was similar to that seen in large observational studies, and was due to a reduction in exacerbations occurring three or more weeks after vaccination. In elderly, high risk patients there was an increase in adverse effects with vaccination, but these are seen early and are usually mild and transient.
authors.affiliation: Medicine, University of Auckland, Private Bag 92019, Auckland, New Zealand. p.poole@auckland.ac.nz
authors.forename: P J
authors.initials: PJ
authors.lastname: Poole
authors.forename: E
authors.initials: E
authors.lastname: Chacko
authors.forename: R W
authors.initials: RW
authors.lastname: Wood-Baker
authors.forename: C J
authors.initials: CJ
authors.lastname: Cates
mesh_terms: D000368:Aged; D006801:Humans; D007252:Influenza Vaccines / Q000009:adverse effects / Q000627:therapeutic use*; D008173:Lung Diseases, Obstructive / Q000150:complications*; D016032:Randomized Controlled Trials as Topic; D014613:Vaccines, Attenuated / Q000009:adverse effects / Q000627:therapeutic use; D015164:Vaccines, Inactivated / Q000009:adverse effects / Q000627:therapeutic use
chemical_list: D007252:Influenza Vaccines; D014613:Vaccines, Attenuated; D015164:Vaccines, Inactivated