title: [Immortal time bias in pharmacoepidemiological studies: definition, solutions and examples].
abstract: Among the observational studies of drug effects in chronic diseases, many of them have found effects that were exaggerated or wrong. Among bias responsible for these errors, the immortal time bias, concerning the definition of exposure and exposure periods, is relevantly important as it usually tends to wrongly attribute a significant benefit to the study drug (or exaggerate a real benefit). In this article, we define the mechanism of immortal time bias, we present possible solutions and illustrate its consequences through examples of pharmacoepidemiological studies of drug effects.
authors.affiliation: Département de pharmacologie médicale et toxicologie, CHRU de Montpellier, Montpellier, France - Service de pharmacologie médicale et clinique, Equipe de recherche de pharmacoépidémiologie, INSERM UMR 1027, CHU de Toulouse, Faculté de médecine Université Paul Sabatier, Toulouse, France.
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Faillie
authors.affiliation: Centre d'épidémiologie clinique, Institut de recherches Lady Davis, Hôpital général juif, Montréal, Québec, Canada - Département d'épidémiologie, de biostatistique et de santé au travail, Université McGill, Montréal, Québec, Canada.
authors.forename: Samy
authors.initials: S
authors.lastname: Suissa
mesh_terms: D015982:Bias; D002908:Chronic Disease; D006801:Humans; D004364:Pharmaceutical Preparations / Q000008:administration & dosage; D017891:Pharmacoepidemiology / Q000379:methods*; D012107:Research Design; D013997:Time Factors
chemical_list: D004364:Pharmaceutical Preparations