scholarly journals Exposure misclassification bias in the estimation of vaccine effectiveness

PLoS ONE ◽  
2021 ◽  
Vol 16 (5) ◽  
pp. e0251622
Author(s):  
Ulrike Baum ◽  
Sangita Kulathinal ◽  
Kari Auranen
Keyword(s):  
Sensitivity And Specificity ◽  
Vaccination Coverage ◽  
Risk Ratio ◽  
Vaccine Effectiveness ◽  
Relative Reduction ◽  
Common Source ◽  
Exposure Misclassification ◽  
Misclassification Bias ◽  
Risk Of Disease ◽  
Differential Exposure

In epidemiology, a typical measure of interest is the risk of disease conditional upon exposure. A common source of bias in the estimation of risks and risk ratios is misclassification. Exposure misclassification affects the measurement of exposure, i.e. the variable one conditions on. This article explains how to assess biases under non-differential exposure misclassification when estimating vaccine effectiveness, i.e. the vaccine-induced relative reduction in the risk of disease. The problem can be described in terms of three binary variables: the unobserved true exposure status, the observed but potentially misclassified exposure status, and the observed true disease status. The bias due to exposure misclassification is quantified by the difference between the naïve estimand defined as one minus the risk ratio comparing individuals observed as vaccinated with individuals observed as unvaccinated, and the vaccine effectiveness defined as one minus the risk ratio comparing truly vaccinated with truly unvaccinated. The magnitude of the bias depends on five factors: the risks of disease in the truly vaccinated and the truly unvaccinated, the sensitivity and specificity of exposure measurement, and vaccination coverage. Non-differential exposure misclassification bias is always negative. In practice, if the sensitivity and specificity are known or estimable from external sources, the true risks and the vaccination coverage can be estimated from the observed data and, thus, the estimation of vaccine effectiveness based on the observed risks can be corrected for exposure misclassification. When analysing risks under misclassification, careful consideration of conditional probabilities is crucial.

scholarly journals Impact of hepatitis B vaccine in Tunisia 20 years after its introduction

2019 ◽  
Vol 29 (Supplement_4) ◽  
Author(s):  
A Lahchaichi ◽  
M Ben Hadj ◽  
H Bouguerra ◽  
K Talmoudi ◽  
A Bahrini ◽  
...  
Keyword(s):  
Hepatitis B ◽  
Vaccination Coverage ◽  
Vaccine Effectiveness ◽  
Coverage Rate ◽  
Hbv Infection ◽  
Hepatitis B Vaccination ◽  
Reference Laboratory ◽  
Test Results ◽  
Vaccination Coverage Rate ◽  
The Impact

Abstract Introduction Vaccination against hepatitis B represents the most effective preventive measure to reduce the global impact of this infection. In Tunisia hepatitis B vaccination was introduced for health professionals in 1992 and for the general population in 1995. The objectives of this study were to evaluate the impact of vaccination twenty years after its introduction. Methods It was a descriptive study of data provided by the national survey of prevalence of Hepatitis B in Tunisia, which was a household-based study conducted in 2015. Blood samples sent to the reference laboratory to test markers of hepatitis B virus infection. The Vaccine effectiveness rate was calculated using the following formula: VE = 1 - Odds-ratio (OR), where OR = ratio of odds of being vaccinated among subjects with positive HBsAg test results to the odds of being vaccinated among subjects with negative HBsAg test results. Results Approximately a quarter of our population reported having been vaccinated against HBV, a coverage rate of 26.9%. Among subjects above 20 years of age, this rate was 85.3%. Besides, 83.7% of vaccinated subjects had received the three required doses of the HBV vaccine. Analysis of vaccination status by great regions of the country showed that the vaccination coverage rate was higher in the southern region. Regarding HBsAg prevalence, the rate was significantly higher among unvaccinated subjects 0.3% vs 2.2% in those vaccinated (OR = 0.11 [0.07-0.18]). We found that among vaccinated subjects, the serologic response rate at vaccination was only 63.2% which represented 16.2% of the total population. The vaccine effectiveness indicated that vaccination reduced by 88.6% the risk of HBV infection. Conclusions These results demonstrate that vaccination against hepatitis B introduced in the national immunization schedule since 1995 has reduced the infection although the vaccination coverage rate remains below 90%. Key messages Importance of vaccination that reduced by 88.6% the risk of HBV infection. More effort required to raise awareness about vaccination against HBV.

Correction of odds ratios in case-control studies for exposure misclassification with partial knowledge of the degree of agreement among experts who assessed exposures

2017 ◽  
Vol 75 (2) ◽  
pp. 155-159 ◽  
Author(s):  
Igor Burstyn ◽  
Paul Gustafson ◽  
Javier Pintos ◽  
Jérôme Lavoué ◽  
Jack Siemiatycki
Keyword(s):  
Exposure Assessment ◽  
Sensitivity And Specificity ◽  
Interrater Reliability ◽  
Credible Interval ◽  
Case Control ◽  
Point Estimate ◽  
Exposure Misclassification ◽  
Odds Ratios ◽  
Case Control Studies ◽  
Distribution Centre

ObjectivesEstimates of association between exposures and diseases are often distorted by error in exposure classification. When the validity of exposure assessment is known, this can be used to adjust these estimates. When exposure is assessed by experts, even if validity is not known, we sometimes have information about interrater reliability. We present a Bayesian method for translating the knowledge of interrater reliability, which is often available, into knowledge about validity, which is often needed but not directly available, and applying this to correct odds ratios (OR).MethodsThe method allows for inclusion of observed potential confounders in the analysis, as is common in regression-based control for confounding. Our method uses a novel type of prior on sensitivity and specificity. The approach is illustrated with data from a case-control study of lung cancer risk and occupational exposure to diesel engine emissions, in which exposure assessment was made by detailed job history interviews with study subjects followed by expert judgement.ResultsUsing interrater agreement measured by kappas (κ), we estimate sensitivity and specificity of exposure assessment and derive misclassification-corrected confounder-adjusted OR. Misclassification-corrected and confounder-adjusted OR obtained with the most defensible prior had a posterior distribution centre of 1.6 with 95% credible interval (Crl) 1.1 to 2.6. This was on average greater in magnitude than frequentist point estimate of 1.3 (95% Crl 1.0 to 1.7).ConclusionsThe method yields insights into the degree of exposure misclassification and appears to reduce attenuation bias due to misclassification of exposure while the estimated uncertainty increased.

scholarly journals Bias due to differential and non-differential disease- and exposure misclassification in studies of vaccine effectiveness

PLoS ONE ◽  
2018 ◽  
Vol 13 (6) ◽  
pp. e0199180 ◽  
Author(s):  
Tom De Smedt ◽  
Elizabeth Merrall ◽  
Denis Macina ◽  
Silvia Perez-Vilar ◽  
Nick Andrews ◽  
...  
Keyword(s):  
Vaccine Effectiveness ◽  
Exposure Misclassification

scholarly journals Familial Intracranial Aneurysms: Recurrence Risk and Accidental Aggregation Study

1997 ◽  
Vol 24 (04) ◽  
pp. 326-331 ◽  
Author(s):  
Jean Mathieu ◽  
Gilles Hébert ◽  
Louis Pérusse ◽  
Claude Prévost ◽  
Léo Cantin ◽  
...  
Keyword(s):  
Risk Ratio ◽  
Genetic Predisposition ◽  
Intracranial Aneurysms ◽  
Familial Aggregation ◽  
Recurrence Risk ◽  
Population Based ◽  
Degree Relative ◽  
Ruptured Intracranial Aneurysm ◽  
Recurrence Risk Ratio ◽  
Risk Of Disease

ABSTRACT:Background:The Saguenay-Lac-Saint-Jean (SLSJ) region is a geographically isolated area (population 285,955) located in the Northeastern part of the Province of Quebec, Canada. Using a population-based register, the genealogical reconstruction of 502 individuals with ruptured intracranial aneurysm (RIA) showed a familial aggregation (the presence of aneurysm in two or more first- to third-degree relatives) for 144 (28.7%) of them; this proportion is much higher than reported elsewhere.Objective:In order to assess the genetic predisposition to RIA in the SLSJ population, the objective of the present study is to compare familial and non-familial cases and to provide an estimate of the recurrence risk ratio for siblings.Results:The age at the time of rupture, the number of intracranial aneurysms for each patient and the location of RIAs were not statistically different in the familial versus the non-familial group. Of the 3449 siblings, 20 (0.58%) had suffered a RIA. The recurrence risk ratio calculated for siblings (defined as the risk of disease among siblings divided by the estimated population prevalence) is 1.6 (CI 95% 1.0 - 2.4). In other respects, we observed very large kinships in the SLSJ population, with an average number of siblings of 7.2 (SD ± 3.4), ranging from 0 to 17 individuals. With such large families and on the basis of chance alone, we expected 31.3% of the patients to have at least one first- to third-degree relative with RIA.Conclusion:These data show that siblings of patients with RIA in the SLSJ population have a greater risk of RIA than the general population. Nevertheless, the largest part of the familial occurrence observed in the SLSJ region can be explained by accidental aggregation, due to large kinships. We propose that, in this population, an underlying genetic predisposition must be suspected only when three or more cases of RIA are identified among first- to third-degree relatives.

scholarly journals Measles Outbreak Amplified in a Pediatric Ward: Lyantonde District, Uganda, August 2017

2020 ◽  
Author(s):  
Claire Biribawa ◽  
Joselyn Annet Atuhairwe ◽  
Lilian Bulage ◽  
Denis Othuba Okethwangu ◽  
Benon Kwesiga ◽  
...  
Keyword(s):  
Vaccination Coverage ◽  
Case Control Study ◽  
Conditional Logistic Regression ◽  
Case Control ◽  
Vaccine Effectiveness ◽  
Pediatric Ward ◽  
Probable Case ◽  
Measles Outbreak ◽  
Isolation Ward ◽  
Control Study

Abstract Background: Measles is a highly infectious viral disease. In August 2017, Lyantonde District, Uganda reported a measles outbreak to Uganda Ministry of Health. We investigated the outbreak to assess the scope, factors facilitating transmission, and recommend control measures. Methods: We defined a probable case as sudden onset of fever and generalized rash in a resident of Lyantonde, Lwengo, or Rakai Districts from 1 June-30 September 2017, plus ≥1 of the following: coryza, conjunctivitis, or cough. A confirmed case was a probable case with serum positivity of measles-specific IgM. We conducted a neighborhood- and age-matched case-control study to identified exposure factors, and used conditional logistic regression to analyze the data. We estimated vaccine effectiveness and vaccination coverage. Findings: We identified 81 cases (75 probable, 6 confirmed); 4 patients (4.9%) died. In the case-control study, 47% of case-patients and 2.3% of controls were hospitalized at Lyantonde Hospital pediatric department for non-measles conditions 7-21 days before case-patient’s onset (OR adj =34, 95%CI: 5.1-225). Estimated vaccine effectiveness was 95% (95%CI: 75-99%) and vaccination coverage was 76% (95%CI: 68-82%). During the outbreak, an “isolation” ward was established inside the general pediatric ward where there was mixing of both measles and non-measles patients. Conclusions This outbreak was amplified by nosocomial transmission and facilitated by low vaccination coverage. We recommended moving the isolation ward outside of the building, supplemental vaccination, and vaccinating pediatric patients during measles outbreaks.

scholarly journals Occupational epidemiologist's quest to tame measurement error in exposure

2019 ◽  
Author(s):  
Igor Burstyn
Keyword(s):  
Measurement Error ◽  
False Positive ◽  
False Negative ◽  
Epidemiologic Study ◽  
Occupational Epidemiology ◽  
Exposure Misclassification ◽  
Exposure Limits ◽  
Workplace Exposure ◽  
Negative Results ◽  
Differential Exposure

I aimed to assess current practices and opportunities for addressing the problem of errors in exposure in occupational epidemiology. Occupational epidemiologists appreciate that errors in exposure are a concern, but almost none correct for these errors, although there are currently no theoretical and practical barriers for this inertia. The most serious barrier to change is a faulty belief that a well-conducted epidemiologic study suffers only non-differential exposure misclassification and that its sole impact is to attenuate risk gradients, causing a false negative. On the contrary, differential exposure misclassification is the most defensible model in occupational epidemiology, and errors in exposure increase chance of both false positive and negative results. Resistance to mathematical adjustment (correction) for errors in exposure is equivalent to denying the value of more valid exposure estimates and undermines the discipline’s relevance to protection of workers by informing workplace exposure limits.

scholarly journals Ongoing mumps outbreak in a student population with high vaccination coverage, Netherlands, 2010

2010 ◽  
Vol 15 (17) ◽  
Author(s):  
J Whelan ◽  
R van Binnendijk ◽  
K Greenland ◽  
E Fanoy ◽  
M Khargi ◽  
...  
Keyword(s):  
Risk Factors ◽  
The Netherlands ◽  
Vaccination Coverage ◽  
Vaccine Effectiveness ◽  
Student Population ◽  
Laboratory Confirmation ◽  
Dose Dependent

Since December 2009, mumps incidence has increased in the Netherlands. As of 20 April 2010, 172 cases have been notified on the basis of laboratory confirmation or linkage to a laboratory-confirmed case. Of these, 112 were students, the majority of whom had been vaccinated (81%). Although outbreaks in vaccinated populations have been described before, risk factors for exposure and susceptibility, and dose-dependent vaccine effectiveness in a student population of this nature are relatively unknown.

Sign in / Sign up

Export Citation Format

Share Document