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Annual Influenza Vaccination in Community-Dwelling Elderly Individuals and the Risk o
Annual Influenza Vaccination in Community-Dwelling Elderly Individuals and the Risk of Lower Respiratory Tract Infections or Pneumonia
Archives of Internal Medicine
Vol. 166 No. 18, October 9, 2006
http://archinte.ama-assn.org/cgi/content/abstract/166/18/1980
Archives of Internal Medicine
Vol. 166 No. 18, October 9, 2006
http://archinte.ama-assn.org/cgi/content/abstract/166/18/1980
<nobr>Bettie C. G. Voordouw, MD, PhD, MPH</nobr>; <nobr>Miriam C. J. M. Sturkenboom, PharmD, PhD</nobr>; <nobr>Jeanne P. Dieleman, PhD</nobr>; <nobr>Theo Stijnen, PhD</nobr>; <nobr>Johan van der Lei, PhD</nobr>; <nobr>Bruno H. C. Stricker, MB, PhD</nobr>
Arch Intern Med. 2006;166:1980-1985.
Arch Intern Med. 2006;166:1980-1985.
Background Influenza vaccination has been associated with<sup> </sup>a reduction in the number of hospitalizations for respiratory<sup> </sup>conditions in elderly persons over the period from 1996 to 2002.<sup> </sup>Little is known, however, about the effect of influenza vaccination<sup> </sup>on the whole range of severity of respiratory tract infections.
Methods We investigated the effect of annual influenza<sup> </sup>vaccination on the occurrence of lower respiratory tract infections<sup> </sup>(LRTIs) in community-dwelling elderly individuals. From 1996<sup> </sup>to 2002, we performed a population-based cohort study, using<sup> </sup>the computerized Integrated Primary Care Information database<sup> </sup>in the Netherlands, of community-dwelling subjects who were<sup> </sup>65 years or older on January 1 of the year of study entry. For<sup> </sup>each year, the individual cumulative exposure to influenza vaccination<sup> </sup>since study entry was computed. We compared the risk of LRTI<sup> </sup>after a first vaccination or revaccination with the risk for<sup> </sup>no vaccination using a time-varying multivariate Cox proportional<sup> </sup>hazard model, adjusted for age, sex, smoking, and underlying<sup> </sup>disease.
Results In the study population of 26 071 subjects,<sup> </sup>3412 developed LRTIs during follow-up. During the influenza<sup> </sup>epidemic periods, a first vaccination did not reduce risk for<sup> </sup>LRTI. In the total population, the hazard ratio following a<sup> </sup>first vaccination was 0.86 (95% confidence interval [CI], 0.71<sup> </sup>to 1.05); in the population without or with comorbidity, these<sup> </sup>ratios were 0.90 (95% CI, 0.56 to 1.45) and 0.83 (95% CI, 0.66<sup> </sup>to 1.04), respectively. During epidemic periods, revaccination<sup> </sup>reduced risk of LRTI by 33% (95% CI, 8% to 52%) in individuals<sup> </sup>without comorbidity. In individuals with comorbidity, the risk<sup> </sup>reduction of 5% was nonsignificant (95% CI, ?10% to 18%).
Conclusion In this study, annual influenza revaccination<sup> </sup>was associated with a reduction in LRTI in community-dwelling<sup> </sup>elderly individuals.
Methods We investigated the effect of annual influenza<sup> </sup>vaccination on the occurrence of lower respiratory tract infections<sup> </sup>(LRTIs) in community-dwelling elderly individuals. From 1996<sup> </sup>to 2002, we performed a population-based cohort study, using<sup> </sup>the computerized Integrated Primary Care Information database<sup> </sup>in the Netherlands, of community-dwelling subjects who were<sup> </sup>65 years or older on January 1 of the year of study entry. For<sup> </sup>each year, the individual cumulative exposure to influenza vaccination<sup> </sup>since study entry was computed. We compared the risk of LRTI<sup> </sup>after a first vaccination or revaccination with the risk for<sup> </sup>no vaccination using a time-varying multivariate Cox proportional<sup> </sup>hazard model, adjusted for age, sex, smoking, and underlying<sup> </sup>disease.
Results In the study population of 26 071 subjects,<sup> </sup>3412 developed LRTIs during follow-up. During the influenza<sup> </sup>epidemic periods, a first vaccination did not reduce risk for<sup> </sup>LRTI. In the total population, the hazard ratio following a<sup> </sup>first vaccination was 0.86 (95% confidence interval [CI], 0.71<sup> </sup>to 1.05); in the population without or with comorbidity, these<sup> </sup>ratios were 0.90 (95% CI, 0.56 to 1.45) and 0.83 (95% CI, 0.66<sup> </sup>to 1.04), respectively. During epidemic periods, revaccination<sup> </sup>reduced risk of LRTI by 33% (95% CI, 8% to 52%) in individuals<sup> </sup>without comorbidity. In individuals with comorbidity, the risk<sup> </sup>reduction of 5% was nonsignificant (95% CI, ?10% to 18%).
Conclusion In this study, annual influenza revaccination<sup> </sup>was associated with a reduction in LRTI in community-dwelling<sup> </sup>elderly individuals.