title: Estimating the generalized impact fraction from case-control data.
abstract: The generalized impact fraction (also called the generalized attributable fraction) was introduced by Walter (1980, American Journal of Epidemiology 112, 409-416) and Morgenstern and Bursic (1982, Journal of Community Health 7, 292-309) as a measure that generalizes the population attributable fraction (attributable risk). It is defined as the fractional reduction of a disease resulting from changing the current distribution of a risk factor to some modified distribution. We show that the point and variance estimator derived by Greenland and Drescher (1993, Biometrics 49, 865-872) for fixed shift functions can be extended to situations where the shift is a probabilistic function of the actual exposure value. The formulas are applicable for case-control designs where the cases are simply randomly selected and the controls are chosen in one of three ways: simple random sampling, stratified random sampling, and frequency matching.
authors.affiliation: Institute of Statistics, University of Bremen, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Drescher
authors.forename: H
authors.initials: H
authors.lastname: Becher
mesh_terms: D000428:Alcohol Drinking; D001699:Biometry / Q000379:methods; D016022:Case-Control Studies; D004812:Epidemiologic Methods; D006801:Humans; D007822:Laryngeal Neoplasms / Q000453:epidemiology / Q000517:prevention & control; D008297:Male; D015233:Models, Statistical; D011336:Probability; D012016:Reference Values; D012044:Regression Analysis; D015203:Reproducibility of Results; D018570:Risk Assessment; D012307:Risk Factors; D012907:Smoking