ArticleVaccine2016
Evaluating the case-positive, control test-negative study design for influenza vaccine effectiveness for the frailty bias.
Article in Vaccine, 2016. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 13 papers, 2 of them syntheses that pooled it.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
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Who cites it
13 citing papers in PubMed, 2 syntheses or guidelines pooled it, 21 citations in OpenAlex.
- Influenza vaccine effectiveness according to frailty status in adults aged ≥ 50 years: a systematic review and meta-analysis.BMC infectious diseases · 2026Pooled it
- The Use of Test-negative Controls to Monitor Vaccine Effectiveness: A Systematic Review of Methodology.Epidemiology (Cambridge, Mass.) · 2020Pooled it
- Influenza Vaccine-Induced Antibody Responses Are Not Impaired by Frailty in the Community-Dwelling Elderly With Natural Influenza Exposure.Frontiers in immunology · 2018Trial
- Roadmap for Sex-Responsive Influenza and COVID-19 Vaccine Research in Older Adults.Frontiers in aging · 2022Review
- Influenza Vaccine Effectiveness Against All-Cause Mortality Following Laboratory-Confirmed Influenza in Older Adults, 2010-2011 to 2015-2016 Seasons in Ontario, Canada.Clinical infectious diseases : an official publication of the Infectious Diseases Society of America · 2021Article
- Frailty Is Associated With Increased Hemagglutination-Inhibition Titers in a 4-Year Randomized Trial Comparing Standard- and High-Dose Influenza Vaccination.Open forum infectious diseases · 2020Article
- Article
- Evaluation of Frailty as an Unmeasured Confounder in Observational Studies of Antidiabetic Medications.The journals of gerontology. Series A, Biological sciences and medical sciences · 2019Observational
- Comparison of a frailty short interview to a validated frailty index in adults hospitalized for acute respiratory illness.Vaccine · 2019Article
- Uptake and effectiveness of influenza vaccine in those aged 65 years and older in the United Kingdom, influenza seasons 2010/11 to 2016/17.Euro surveillance : bulletin Europeen sur les maladies transmissibles = European communicable disease bulletin · 2018Article
- Healthy elderly Singaporeans show no age-related humoral hyporesponsiveness nor diminished plasmablast generation in response to influenza vaccine.Immunity & ageing : I & A · 2018Article
- A comparison of the test-negative and the traditional case-control study designs for estimation of influenza vaccine effectiveness under nonrandom vaccination.BMC infectious diseases · 2017Article
- Influenza vaccine response in community-dwelling German prefrail and frail individuals.Immunity & ageing : I & A · 2017Article
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Authors and funding
6 authors at 2 institutions in 1 country.
Funding
Abstract
introductionPrevious influenza vaccine effectiveness studies were criticized for their failure to control for frailty. This study was designed to see if the test-negative study design overcomes this bias.
methodsAdults ≥ 50 years of age with respiratory symptoms were enrolled from November 2006 through May 2012 during the influenza season (excluding the 2009-2010 H1N1 pandemic season) to perform yearly test-negative control influenza vaccine effectiveness studies in Nashville, TN. At enrollment, both a nasal and throat swab sample were obtained and tested for influenza by RT-PCR. Frailty was calculated using a modified Rockwood Index that included 60 variables ascertained in a retrospective chart review giving a score of 0 to 1. Subjects were divided into three strata: non frail (≤ 0.08), pre-frail (> 0.08 to < 0.25), and frail (≥ 0.25). Vaccine effectiveness was calculated using the formula [1-adjusted odds ratio (OR)] × 100%. Adjusted ORs for individual years and all years combined were estimated by penalized multivariable logistic regression.
resultsOf 1023 hospitalized adults enrolled, 866 (84.7%) participants had complete immunization status, molecular influenza testing and covariates to calculate frailty. There were 83 influenza-positive cases and 783 test-negative controls overall, who were 74% white, 25% black, and 59% female. The median frailty index was 0.167 (Interquartile: 0.117, 0.267). The frailty index was 0.167 (0.100, 0.233) for the influenza positive cases compared to 0.183 (0.133, 0.267) for influenza negative controls (p = 0.07). Vaccine effectiveness estimates were 55.2% (95%CI: 30.5, 74.2), 60.4% (95%CI: 29.5, 74.4), and 54.3% (95%CI: 28.8, 74.0) without the frailty variable, including frailty as a continuous variable, and including frailty as a categorical variable, respectively.
conclusionsUsing the case positive test negative study design to assess vaccine effectiveness, our measure of frailty was not a significant confounder as inclusion of this measure did not significantly change vaccine effectiveness estimates.
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