title: Assessing case definitions in the absence of a diagnostic gold standard.
abstract: Optimal case definition is important in epidemiological research, but can be problematic when no satisfactory gold standard is available. In particular, difficulties arise where the pathology underlying a disorder is unknown or cannot be reliably diagnosed. This problem can be overcome if diagnoses are viewed not necessarily as labels for disease processes, but more generally as a useful method for classifying people for the purpose of preventing or managing illness. With this perspective, the value of a case definition lies in its practical utility in distinguishing groups of people whose illnesses share the same causes or determinants of outcome (including response to treatment). A corollary is that the best-case definition for a disorder may vary according to the purpose for which it is being applied.
authors.affiliation: MRC Environmental Epidemiology Unit, University of Southampton, Southampton General Hospital, Southampton SO16 6YD, UK. dnc@mrc.soton.ac.uk
authors.forename: David
authors.initials: D
authors.lastname: Coggon
authors.forename: Christopher
authors.initials: C
authors.lastname: Martyn
authors.forename: Keith T
authors.initials: KT
authors.lastname: Palmer
authors.forename: Bradley
authors.initials: B
authors.lastname: Evanoff
mesh_terms: D003933:Diagnosis; D004194:Disease / Q000145:classification*; D004812:Epidemiologic Methods; D006801:Humans; D015233:Models, Statistical