Effects of annual influenza vaccination on winter mortality in elderly people with chronic pulmonary disease

Abstract

Background: Although there is a general agreement for the recommendation of the influenza vaccine to persons with chronic obstructive pulmonary disease (COPD), the magnitude of clinical effectiveness and benefit from the annual vaccination is controversial. We assessed the effects of annual influenza vaccination on winter mortality in older adults with COPD.

Methods: This prospective cohort study included 1298 Spanish community-dwelling individuals aged 65 years or older with a diagnosis of COPD followed from 1 January 2002 to 30 April 2005. The primary outcome was all-cause death during influenza periods (January-April). Multivariable Cox proportional hazard models adjusted by age, sex and comorbidity were used to evaluate vaccine effectiveness.

Results: Influenza vaccination was associated with a non-statistically significant 16% reduction in winter mortality among vaccinated COPD patients [unadjusted hazard ratio (HR): 0.84; 95% confidence interval (CI): 0.60-1.17]. Multivariable analysis showed that there was an insignificant trend towards a reduced mortality in the vaccinated group considering overall influenza periods 2002-2005 (adjusted HR: 0.76; 95% CI: 0.52-1.06; p=0.098). We estimated that, in the total COPD population, one death was prevented for every 187 annual vaccinations (95% CI: 62 to infinity).

Conclusions: Our data suggest benefit from the influenza vaccination and support an annual vaccination strategy for elderly COPD patients.