title: Case ascertainment and estimated incidence of drug-induced long-QT syndrome: study in Southwest France.
abstract: OBJECTIVE
  The aim of this study was to investigate the incidence and reporting rate of drug-induced long-QT syndrome (LQTS) in France [defined by evidence of torsades de pointes (TdP), QT prolongation and exposure to a relevant drug] and to assess feasibility of case collection for drug-induced LQTS.
  
  
  METHODS
  A retrospective population-based study was carried out in Southwest France in five institutions: three main hospitals, one private clinic and one cardiac emergency unit, searched from 1 January 1999 to 1 January 2005 (population coverage of 614 000). The study population consisted of 861 cases with International Classification of Diseases-10 diagnostic codes for ventricular tachycardia (I147.2), ventricular fibrillation (I149.0) and sudden cardiac death (I146.1) from hospital discharge summaries, supplemented by cases reported to national or regional pharmacovigilance systems, and voluntary reporting by physicians, validated according to internationally defined criteria for drug-induced LQTS.
  
  
  RESULTS
  Of 861 patients coded with arrhythmias or sudden cardiac death, there were 40 confirmed surviving acquired cases of drug-induced LQTS. We estimated that the incidence of those who survive to reach hospital drug-induced LQTS is approximately 10.9 per million annually in France (95% confidence interval 7.8, 14.8).
  
  
  CONCLUSIONS
  Many cases of drug-induced LQTS may not survive before they reach hospital, as the reporting rate for drug-induced LQTS identified through the cardiology records and also reported to pharmacovigilance systems for the Midi-Pyrenees area is 3/40 (7.5%). Using the methods outlined it is possible to assemble cases to study genetic susceptibility to drug-induced LQTS and adapt these methods more widely.
authors.affiliation: Non-Communicable Disease Epidemiology UnitLondon School of Hygiene & Tropical MedicineKeppel Street, WC1E 7HT London, UK. mariam.molokhia@lshtm.ac.uk
authors.forename: Mariam
authors.initials: M
authors.lastname: Molokhia
authors.forename: Atul
authors.initials: A
authors.lastname: Pathak
authors.forename: Maryse
authors.initials: M
authors.lastname: Lapeyre-Mestre
authors.forename: Laetitia
authors.initials: L
authors.lastname: Caturla
authors.forename: Jean Louis
authors.initials: JL
authors.lastname: Montastruc
authors.forename: Paul
authors.initials: P
authors.lastname: McKeigue
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000889:Anti-Arrhythmia Agents / Q000008:administration & dosage / Q000009:adverse effects*; D001281:Atrial Fibrillation / Q000139:chemically induced*; D016757:Death, Sudden, Cardiac / Q000453:epidemiology; D004562:Electrocardiography; D005240:Feasibility Studies; D005260:Female; D005602:France; D020022:Genetic Predisposition to Disease; D006801:Humans; D015994:Incidence; D008133:Long QT Syndrome / Q000139:chemically induced* / Q000453:epidemiology / Q000235:genetics; D008297:Male; D008875:Middle Aged; D015221:Potassium Channels; D012189:Retrospective Studies; D012307:Risk Factors; D016171:Torsades de Pointes / Q000139:chemically induced* / Q000453:epidemiology / Q000235:genetics
chemical_list: D000889:Anti-Arrhythmia Agents; D015221:Potassium Channels