title: Acute respiratory illness in patients with COPD and the effectiveness of influenza vaccination: a randomized controlled study.
abstract: OBJECTIVE
  To determine the effectiveness of influenza vaccination on influenza-related acute respiratory illness (ARI) and overall ARI in patients with COPD, and its relationship to the degree of airflow obstruction.
  
  
  METHODS
  Stratified, randomized, double-blind, placebo-controlled trial.
  
  
  METHODS
  From June 1997 to November 1998 at a single university hospital.
  
  
  METHODS
  One hundred twenty-five patients with COPD were stratified based on their FEV(1) as having mild, moderate, and severe COPD. Within each group, they were randomized to the vaccine group (62 patients who received purified, trivalent, split-virus vaccine) or the placebo group (63 patients).
  
  
  METHODS
  The number of episodes and severity of total ARI, classified as outpatient treatment, hospitalization, and requirement of mechanical ventilation; and the number of episodes and severity of influenza-related ARI.
  
  
  RESULTS
  The incidence of influenza-related ARI was 28.1 per 100 person-years and 6.8 per 100 person-years in the placebo group and vaccine group, respectively (relative risk [RR], 0.24 [p = 0.005]; vaccine effectiveness, 76%). The incidences were 28.2, 23.8, and 31.2 per 100 person-years in the patients with mild, moderate, and severe COPD, respectively, in the placebo group, and 4.5, 13.2, and 4.6 per 100 person-years in the patients with mild, moderate, and severe COPD, respectively, in the vaccine group (RR, 0.16 [p = 0.06]; vaccine effectiveness, 84%; RR, 0.55 [p = 0.5]; vaccine effectiveness, 45%; and RR, 0.15 [p = 0.04]; vaccine effectiveness, 85%, in the patients with mild, moderate, and severe COPD, respectively). Bivariate analysis revealed that the effectiveness of influenza vaccination was not modified by the severity of COPD, comorbid diseases, age, gender, or current smoking status. There was no difference in the incidence or severity of total ARI between the placebo group and the vaccine group.
  
  
  CONCLUSIONS
  Influenza vaccination is highly effective in the prevention of influenza-related ARI regardless of the severity of COPD. Influenza vaccination does not prevent other ARIs unrelated to influenza. The effectiveness of influenza vaccination in the prevention of overall ARI in patients with COPD will depend on how much the proportion of influenza-related ARI contributes to the incidence of total ARI. Influenza vaccination should be recommended to all patients with COPD.
authors.affiliation: Division of Respiratory Disease and Tuberculosis, Department of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand. sipwo@maidaol.ac.th
authors.forename: Phunsup
authors.initials: P
authors.lastname: Wongsurakiat
authors.forename: Khun Nanta
authors.initials: KN
authors.lastname: Maranetra
authors.forename: Chantapong
authors.initials: C
authors.lastname: Wasi
authors.forename: Uraiwan
authors.initials: U
authors.lastname: Kositanont
authors.forename: Wanchai
authors.initials: W
authors.lastname: Dejsomritrutai
authors.forename: Suchai
authors.initials: S
authors.lastname: Charoenratanakul
mesh_terms: D000367:Age Factors; D000368:Aged; D015897:Comorbidity; D004311:Double-Blind Method; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007252:Influenza Vaccines / Q000008:administration & dosage*; D007251:Influenza, Human / Q000453:epidemiology / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D016012:Poisson Distribution; D011336:Probability; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis* / Q000453:epidemiology; D012016:Reference Values; D012141:Respiratory Tract Infections / Q000453:epidemiology / Q000517:prevention & control*; D018570:Risk Assessment; D012720:Severity of Illness Index; D012737:Sex Factors; D014611:Vaccination / Q000379:methods*
chemical_list: D007252:Influenza Vaccines