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

The Institute for Clinical Evaluative Sciences, Toronto, Canada.
Vaccine (Impact Factor: 3.62). 10/2010; 29(2):240-6. DOI: 10.1016/j.vaccine.2010.10.049
Source: PubMed


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.

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    • "Although the number of individuals tested for cytokine response in our study is too low to draw any firm conclusions, our data suggest a fine line between the benefits of having a strong pro-inflammatory response , which would allow a better control of infections, and the negative side effects accompanying it in terms of inflammation-associated pathologies, such as cardiovascular diseases or cancer. Numerous studies dating as far back as the 1980s have repeatedly shown that vaccination with influenza is associated with a strong reduction in not only pneumoniaor flu-related but surprisingly also all-cause-as well as cardiovascular mortality rates (Barker and Mullooly 1980; Nichol et al. 2003, 2007; Campitelli et al. 2010). "
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    Full-text · Article · Jun 2012 · Age
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    • "Elderly patients (Nichol et al., 1994) and patients with chronic lung or heart disease (Baltussen et al., 1998;Nichol et al., 2003) are especially at risk for influenza-related complications. Previous studies have shown that influenza vaccination can reduce hospitalization of patients with heart and lung disease (Hak et al., 2002;Nichol et al., 2003;Wang et al., 2004) and reduce all-cause mortality in the elderly (Campitelli et al., 2010;Nichol, 2005;Voordouw et al., 2004). However, few large-scale studies have investigated the impact of vaccination in elderly patients with ischemic heart disease (IHD), and the benefits of vaccination in these patients has remained undetermined (de Diego et al., 2009). "

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