title: Channeling bias in the interpretation of drug effects.
abstract: Channeling is a form of allocation bias, where drugs with similar therapeutic indications are prescribed to groups of patients with prognostic differences. Claimed advantages of a new drug may channel it to patients with special pre-existing morbidity, with the consequence that disease states can be incorrectly attributed to use of the drug. For the study of adverse drug reactions, large databases supply information on co-medication and morbidity of patients. For diseases with a stepped-care approach, the drug history of patients, as available from some databases, can show channeling of drugs to patients with markers of relatively severe disease.
authors.affiliation: Department of Epidemiology, University of Limburg, Maastricht, The Netherlands.
authors.forename: H
authors.initials: H
authors.lastname: Petri
authors.forename: J
authors.initials: J
authors.lastname: Urquhart
mesh_terms: D001249:Asthma / Q000188:drug therapy; D015982:Bias; D016303:Clinical Pharmacy Information Systems; D003710:Demography; D004358:Drug Therapy; D004363:Drug Utilization; D064420:Drug-Related Side Effects and Adverse Reactions; D006801:Humans; D012107:Research Design