title: Estimating marginal causal effects in a secondary analysis of case-control data.
abstract: When an initial case-control study is performed, data can be used in a secondary analysis to evaluate the effect of the case-defining event on later outcomes. In this paper, we study the example in which the role of the event is changed from a response variable to a treatment of interest. If the aim is to estimate marginal effects, such as average effects in the population, the sampling scheme needs to be adjusted for. We study estimators of the average effect of the treatment in a secondary analysis of matched and unmatched case-control data where the probability of being a case is known. For a general class of estimators, we show the components of the bias resulting from ignoring the sampling scheme and demonstrate a design-weighted matching estimator of the average causal effect. In simulations, the finite sample properties of the design-weighted matching estimator are studied. Using a Swedish diabetes incidence register with a matched case-control design, we study the effect of childhood onset diabetes on the use of antidepressant medication as an adult. Copyright © 2017 John Wiley & Sons, Ltd.
authors.affiliation: Department of Statistics, USBE, Umeå University, SE-90187, Umeå, Sweden.
authors.forename: Emma
authors.identifier: 0000-0002-1174-5126
authors.initials: E
authors.lastname: Persson
authors.affiliation: Department of Statistics, USBE, Umeå University, SE-90187, Umeå, Sweden.
authors.forename: Ingeborg
authors.initials: I
authors.lastname: Waernbaum
authors.affiliation: Department of Clinical Sciences, Pediatrics, Umeå University, SE-90187, Umeå, Sweden.
authors.forename: Torbjörn
authors.initials: T
authors.lastname: Lind
mesh_terms: D000928:Antidepressive Agents / Q000627:therapeutic use; D015982:Bias; D056808:Biostatistics; D016022:Case-Control Studies; D002648:Child; D003198:Computer Simulation; D003627:Data Interpretation, Statistical; D003922:Diabetes Mellitus, Type 1 / Q000188:drug therapy / Q000523:psychology; D005260:Female; D006801:Humans; D008297:Male; D015233:Models, Statistical; D012494:Sampling Studies; D013548:Sweden; D016896:Treatment Outcome
chemical_list: D000928:Antidepressive Agents
keywords: design-weighted estimation; matched case-control study; propensity score