title: [Population attributable fraction: estimation and interpretation].
abstract: The goal of this paper is to revise the concept, estimation methods, and interpretations of the population attributable fraction. From the usual formula of the population attributable fraction: (Ip ­ I₀) / Ip, where Ip is the cumulative incidence in the overall population, and I₀ is the cumulative incidence in the non-exposed group, other formulae are presented for use in exposures with more than two levels, and in the presence of confounding factors. Differences in estimation methods between cohort and case-control studies are discussed, and equations to estimate confidence intervals are displayed. Finally, some interpretations -­including the concepts of «etiologic case» and «case in excess», suggested by Greenland and Robbins-­, and some habitual errors are discussed.
authors.affiliation: Cátedra de Medicina Preventiva y Salud Pública. Facultad de Medicina. Universidad de Cantabria.
authors.forename: J
authors.initials: J
authors.lastname: Llorca
authors.forename: C
authors.initials: C
authors.lastname: Fariñas-Álvareza
authors.forename: M
authors.initials: M
authors.lastname: Delgado-Rodrígueza
mesh_terms: D016022:Case-Control Studies; D015331:Cohort Studies; D004812:Epidemiologic Methods; D006801:Humans; D018570:Risk Assessment; D013223:Statistics as Topic