title: Case-base methods for studying vaccination safety.
abstract: Pooling of controls under nested-case control settings can produce substantial efficiency gains compared to standard time-matched analysis using the Mantel-Haenszel method or conditional logistic regression. In the context of possible adverse effects of early childhood vaccinations, we propose pooling of the information from the controls to estimate the population exposure prevalence as a parametric or nonparametric function of time, and possibly other factors. This function in turn may be used as a plug-in estimate to control for confounding in the subsequent estimation of rate ratios. We derive standard errors for the resulting two-step estimators, demonstrate through simulations the efficiency gains compared to standard matched analysis, and propose a novel graphical presentation of the vaccination and adverse event time data. We formulate the methods in the general framework of case-base sampling, which subsumes the different case-control and case-only methods.
authors.affiliation: Dalla Lana School of Public Health, University of Toronto, 155 College Street, 6th floor, Toronto, Ontario, Canada M5T 3M7.
authors.forename: Olli
authors.initials: O
authors.lastname: Saarela
authors.affiliation: Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Purvis Hall, 1020 Pine Avenue West, Montreal, Quebec, Canada H3A 1A2.
authors.forename: James A
authors.initials: JA
authors.lastname: Hanley
mesh_terms: D016022:Case-Control Studies; D003198:Computer Simulation; D003627:Data Interpretation, Statistical; D064420:Drug-Related Side Effects and Adverse Reactions / Q000453:epidemiology*; D004812:Epidemiologic Methods; D006801:Humans; D015994:Incidence; D015233:Models, Statistical; D018570:Risk Assessment / Q000379:methods; D014611:Vaccination / Q000706:statistics & numerical data*; D014777:Virus Diseases / Q000453:epidemiology* / Q000517:prevention & control*
keywords: Case-base study; Efficiency; Etiologic study; Nested case-control study; Self-matching; Vaccination study; Variance estimation