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Effectiveness of inactivated influenza vaccines in preventing influenza-associated deaths and hospitalizations among Ontario residents aged ≥ 65 years: estimates with generalized linear models accounting for healthy vaccinee effects.
PLoS One 2013; 8(10):e76318Plos

Abstract

BACKGROUND

Estimates of the effectiveness of influenza vaccines in older adults may be biased because of difficulties identifying and adjusting for confounders of the vaccine-outcome association. We estimated vaccine effectiveness for prevention of serious influenza complications among older persons by using methods to account for underlying differences in risk for these complications.

METHODS

We conducted a retrospective cohort study among Ontario residents aged ≥ 65 years from September 1993 through September 2008. We linked weekly vaccination, hospitalization, and death records for 1.4 million community-dwelling persons aged ≥ 65 years. Vaccine effectiveness was estimated by comparing ratios of outcome rates during weeks of high versus low influenza activity (defined by viral surveillance data) among vaccinated and unvaccinated subjects by using log-linear regression models that accounted for temperature and time trends with natural spline functions. Effectiveness was estimated for three influenza-associated outcomes: all-cause deaths, deaths occurring within 30 days of pneumonia/influenza hospitalizations, and pneumonia/influenza hospitalizations.

RESULTS

During weeks when 5% of respiratory specimens tested positive for influenza A, vaccine effectiveness among persons aged ≥ 65 years was 22% (95% confidence interval [CI], -6%-42%) for all influenza-associated deaths, 25% (95% CI, 13%-37%) for deaths occurring within 30 days after an influenza-associated pneumonia/influenza hospitalization, and 19% (95% CI, 4%-31%) for influenza-associated pneumonia/influenza hospitalizations. Because small proportions of deaths, deaths after pneumonia/influenza hospitalizations, and pneumonia/influenza hospitalizations were associated with influenza virus circulation, we estimated that vaccination prevented 1.6%, 4.8%, and 4.1% of these outcomes, respectively.

CONCLUSIONS

By using confounding-reducing techniques with 15 years of provincial-level data including vaccination and health outcomes, we estimated that influenza vaccination prevented ~4% of influenza-associated hospitalizations and deaths occurring after hospitalizations among older adults in Ontario.

Authors+Show Affiliations

Influenza Division, United States Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America ; Eck Institute for Global Health, Department of Biological Sciences, University of Notre Dame, South Bend, Indiana, United States of America.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

24146855

Citation

Ridenhour, Benjamin J., et al. "Effectiveness of Inactivated Influenza Vaccines in Preventing Influenza-associated Deaths and Hospitalizations Among Ontario Residents Aged ≥ 65 Years: Estimates With Generalized Linear Models Accounting for Healthy Vaccinee Effects." PloS One, vol. 8, no. 10, 2013, pp. e76318.
Ridenhour BJ, Campitelli MA, Kwong JC, et al. Effectiveness of inactivated influenza vaccines in preventing influenza-associated deaths and hospitalizations among Ontario residents aged ≥ 65 years: estimates with generalized linear models accounting for healthy vaccinee effects. PLoS ONE. 2013;8(10):e76318.
Ridenhour, B. J., Campitelli, M. A., Kwong, J. C., Rosella, L. C., Armstrong, B. G., Mangtani, P., ... Shay, D. K. (2013). Effectiveness of inactivated influenza vaccines in preventing influenza-associated deaths and hospitalizations among Ontario residents aged ≥ 65 years: estimates with generalized linear models accounting for healthy vaccinee effects. PloS One, 8(10), pp. e76318. doi:10.1371/journal.pone.0076318.
Ridenhour BJ, et al. Effectiveness of Inactivated Influenza Vaccines in Preventing Influenza-associated Deaths and Hospitalizations Among Ontario Residents Aged ≥ 65 Years: Estimates With Generalized Linear Models Accounting for Healthy Vaccinee Effects. PLoS ONE. 2013;8(10):e76318. PubMed PMID: 24146855.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effectiveness of inactivated influenza vaccines in preventing influenza-associated deaths and hospitalizations among Ontario residents aged ≥ 65 years: estimates with generalized linear models accounting for healthy vaccinee effects. AU - Ridenhour,Benjamin J, AU - Campitelli,Michael A, AU - Kwong,Jeffrey C, AU - Rosella,Laura C, AU - Armstrong,Ben G, AU - Mangtani,Punam, AU - Calzavara,Andrew J, AU - Shay,David K, Y1 - 2013/10/16/ PY - 2013/04/29/received PY - 2013/08/23/accepted PY - 2013/10/23/entrez PY - 2013/10/23/pubmed PY - 2014/8/15/medline SP - e76318 EP - e76318 JF - PloS one JO - PLoS ONE VL - 8 IS - 10 N2 - BACKGROUND: Estimates of the effectiveness of influenza vaccines in older adults may be biased because of difficulties identifying and adjusting for confounders of the vaccine-outcome association. We estimated vaccine effectiveness for prevention of serious influenza complications among older persons by using methods to account for underlying differences in risk for these complications. METHODS: We conducted a retrospective cohort study among Ontario residents aged ≥ 65 years from September 1993 through September 2008. We linked weekly vaccination, hospitalization, and death records for 1.4 million community-dwelling persons aged ≥ 65 years. Vaccine effectiveness was estimated by comparing ratios of outcome rates during weeks of high versus low influenza activity (defined by viral surveillance data) among vaccinated and unvaccinated subjects by using log-linear regression models that accounted for temperature and time trends with natural spline functions. Effectiveness was estimated for three influenza-associated outcomes: all-cause deaths, deaths occurring within 30 days of pneumonia/influenza hospitalizations, and pneumonia/influenza hospitalizations. RESULTS: During weeks when 5% of respiratory specimens tested positive for influenza A, vaccine effectiveness among persons aged ≥ 65 years was 22% (95% confidence interval [CI], -6%-42%) for all influenza-associated deaths, 25% (95% CI, 13%-37%) for deaths occurring within 30 days after an influenza-associated pneumonia/influenza hospitalization, and 19% (95% CI, 4%-31%) for influenza-associated pneumonia/influenza hospitalizations. Because small proportions of deaths, deaths after pneumonia/influenza hospitalizations, and pneumonia/influenza hospitalizations were associated with influenza virus circulation, we estimated that vaccination prevented 1.6%, 4.8%, and 4.1% of these outcomes, respectively. CONCLUSIONS: By using confounding-reducing techniques with 15 years of provincial-level data including vaccination and health outcomes, we estimated that influenza vaccination prevented ~4% of influenza-associated hospitalizations and deaths occurring after hospitalizations among older adults in Ontario. SN - 1932-6203 UR - https://www.unboundmedicine.com/medline/citation/24146855/Effectiveness_of_inactivated_influenza_vaccines_in_preventing_influenza_associated_deaths_and_hospitalizations_among_Ontario_residents_aged_≥_65_years:_estimates_with_generalized_linear_models_accounting_for_healthy_vaccinee_effects_ L2 - http://dx.plos.org/10.1371/journal.pone.0076318 DB - PRIME DP - Unbound Medicine ER -