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Influenza vaccine effectiveness in patients on hemodialysis: an analysis of a natural experiment.
Arch Intern Med. 2012 Apr 09; 172(7):548-54.AI

Abstract

BACKGROUND

Although the influenza vaccine is recommended for patients with end-stage renal disease, little is known about its effectiveness. Observational studies of vaccine effectiveness (VE) are challenging because vaccinated subjects may be healthier than unvaccinated subjects.

METHODS

Using US Renal Data System data, we estimated VE for influenza-like illness, influenza/pneumonia hospitalization, and mortality in adult patients undergoing hemodialysis by using a natural experiment created by the year-to-year variation in the match of the influenza vaccine to the circulating virus. We compared vaccinated patients in matched years (1998, 1999, and 2001) with a mismatched year (1997) using Cox proportional hazards models. Ratios of hazard ratios compared vaccinated patients between 2 years and unvaccinated patients between 2 years. We calculated VE as 1 - effect measure.

RESULTS

Vaccination rates were less than 50% each year. Conventional analysis comparing vaccinated with unvaccinated patients produced average VE estimates of 13%, 16%, and 30% for influenza-like illness, influenza/pneumonia hospitalization, and mortality, respectively. When restricted to the preinfluenza period, results were even stronger, indicating bias. The pooled ratio of hazard ratios comparing matched seasons with a placebo season resulted in a VE of 0% (95% CI, -3% to 2%) for influenza-like illness, 2% (-2% to 5%) for hospitalization, and 0% (-3% to 3%) for death.

CONCLUSIONS

Relative to a mismatched year, we found little evidence of increased VE in subsequent well-matched years, suggesting that the current influenza vaccine strategy may have a smaller effect on morbidity and mortality in the end-stage renal disease population than previously thought. Alternate strategies (eg, high-dose vaccine, adjuvanted vaccine, and multiple doses) should be investigated.

Authors+Show Affiliations

Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC 27599-7435, USA.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

22493462

Citation

McGrath, Leah J., et al. "Influenza Vaccine Effectiveness in Patients On Hemodialysis: an Analysis of a Natural Experiment." Archives of Internal Medicine, vol. 172, no. 7, 2012, pp. 548-54.
McGrath LJ, Kshirsagar AV, Cole SR, et al. Influenza vaccine effectiveness in patients on hemodialysis: an analysis of a natural experiment. Arch Intern Med. 2012;172(7):548-54.
McGrath, L. J., Kshirsagar, A. V., Cole, S. R., Wang, L., Weber, D. J., Stürmer, T., & Brookhart, M. A. (2012). Influenza vaccine effectiveness in patients on hemodialysis: an analysis of a natural experiment. Archives of Internal Medicine, 172(7), 548-54. https://doi.org/10.1001/archinternmed.2011.2238
McGrath LJ, et al. Influenza Vaccine Effectiveness in Patients On Hemodialysis: an Analysis of a Natural Experiment. Arch Intern Med. 2012 Apr 9;172(7):548-54. PubMed PMID: 22493462.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Influenza vaccine effectiveness in patients on hemodialysis: an analysis of a natural experiment. AU - McGrath,Leah J, AU - Kshirsagar,Abhijit V, AU - Cole,Stephen R, AU - Wang,Lily, AU - Weber,David J, AU - Stürmer,Til, AU - Brookhart,M Alan, PY - 2012/4/12/entrez PY - 2012/4/12/pubmed PY - 2012/5/30/medline SP - 548 EP - 54 JF - Archives of internal medicine JO - Arch. Intern. Med. VL - 172 IS - 7 N2 - BACKGROUND: Although the influenza vaccine is recommended for patients with end-stage renal disease, little is known about its effectiveness. Observational studies of vaccine effectiveness (VE) are challenging because vaccinated subjects may be healthier than unvaccinated subjects. METHODS: Using US Renal Data System data, we estimated VE for influenza-like illness, influenza/pneumonia hospitalization, and mortality in adult patients undergoing hemodialysis by using a natural experiment created by the year-to-year variation in the match of the influenza vaccine to the circulating virus. We compared vaccinated patients in matched years (1998, 1999, and 2001) with a mismatched year (1997) using Cox proportional hazards models. Ratios of hazard ratios compared vaccinated patients between 2 years and unvaccinated patients between 2 years. We calculated VE as 1 - effect measure. RESULTS: Vaccination rates were less than 50% each year. Conventional analysis comparing vaccinated with unvaccinated patients produced average VE estimates of 13%, 16%, and 30% for influenza-like illness, influenza/pneumonia hospitalization, and mortality, respectively. When restricted to the preinfluenza period, results were even stronger, indicating bias. The pooled ratio of hazard ratios comparing matched seasons with a placebo season resulted in a VE of 0% (95% CI, -3% to 2%) for influenza-like illness, 2% (-2% to 5%) for hospitalization, and 0% (-3% to 3%) for death. CONCLUSIONS: Relative to a mismatched year, we found little evidence of increased VE in subsequent well-matched years, suggesting that the current influenza vaccine strategy may have a smaller effect on morbidity and mortality in the end-stage renal disease population than previously thought. Alternate strategies (eg, high-dose vaccine, adjuvanted vaccine, and multiple doses) should be investigated. SN - 1538-3679 UR - https://www.unboundmedicine.com/medline/citation/22493462/Influenza_vaccine_effectiveness_in_patients_on_hemodialysis:_an_analysis_of_a_natural_experiment_ L2 - https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/10.1001/archinternmed.2011.2238 DB - PRIME DP - Unbound Medicine ER -