Influenza vaccination and all-cause mortality in community-dwelling elderly in Ontario, Canada, a cohort study

Published: October 31, 2010
Category: Bibliography > Papers
Authors: Campitelli MA, Kwong JC, Rosella LC, Stukel TA
Countries: Canada
Language: null
Types: Population Health
Settings: Academic

Vaccine 29:240-246.

Institute for Clinical Evaluative Sciences, Toronto, ON, Canada

The objective of this study was to evaluate the effectiveness of influenza vaccines in reducing all-cause mortality among community-dwelling elderly. We included 25,922 Ontario residents over age 65 who responded to population health surveys. After full adjustment, influenza vaccination was associated with a statistically significant reduction in all-cause mortality during influenza seasons (hazard ratio (HR)=0.61; 95% CI 0.47-0.79). Contrary to expectations, statistically significant associations between influenza vaccination and mortality were also observed during periods preceding (HR=0.55; 95% CI 0.40-0.75) and following (HR=0.74; 95% CI 0.59-0.94) influenza seasons, indicating the presence of residual confounding. Adjustment for functional status indicators, excluding individuals with high one-year predicted mortality at baseline, and moving the start date of follow-up failed to eliminate the refractory confounding. Since observational studies are prone to bias, future efforts to estimate vaccine effectiveness in the elderly should strive to minimize bias through improved data quality, novel data sources, and/or new analytical techniques.

PMID: 21044667

Total Disease Burden,Mortality Prediction,Age,Predictive Risk Modeling,Canada,80 and over,Cohort Studies,Gender,Influenza Vaccines/administration & dosage,Ontario/epidemiology,Seasons

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