title: Determinants of torsades de pointes in older patients with drug-associated long QT syndrome: a case-control study.
abstract: OBJECTIVE
  Many elderly patients are routinely exposed to drugs that may prolong the cardiac QT interval and cause Torsades de pointes (TdP). However, predictors of TdP in patients with drug-associated long QT syndrome (LQTS) are not fully understood, especially in the geriatric population. The objective of this study was to identify risk factors of TdP in elderly patients with drug-associated LQTS.
  
  
  METHODS
  In this retrospective, case-control study, documented reports of drug-associated LQTS plus TdP (n = 125) and LQTS without TdP (n = 81) in patients ≥65 years of age were retrieved from the French Pharmacovigilance Database over a 10-year period. Available clinical, biological, and drug therapy data were compared in the two groups and logistic regression was performed to identify significant predictors of TdP.
  
  
  RESULTS
  The uncorrected QT interval was significantly longer in patients with TdP than in patients without TdP (577 ± 79 vs. 519 ± 68 ms; p = 0.0001). The number of drugs with a known risk of TdP administered to each patient was not a predictor of arrhythmia, nor was female gender. Logistic regression analysis identified the uncorrected QT interval as the only significant predictor of TdP. The receiver operating characteristic curve analysis was characterized by an area under the curve of 0.77 (95 % confidence interval 0.64-0.88) and a QT cutoff of 550 ms.
  
  
  CONCLUSIONS
  The uncorrected QT interval was significantly associated with the probability of TdP in elderly patients with acquired, drug-associated LQTS.
authors.affiliation: Hospices Civils de Lyon, Groupement Hospitalier de Gériatrie, Service Pharmaceutique, Lyon, France, sylvain.goutelle@chu-lyon.fr.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Goutelle
authors.forename: Elodie
authors.initials: E
authors.lastname: Sidolle
authors.forename: Michel
authors.initials: M
authors.lastname: Ducher
authors.forename: Jacques
authors.initials: J
authors.lastname: Caron
authors.forename: Quadiri
authors.initials: Q
authors.lastname: Timour
authors.forename: Patrice
authors.initials: P
authors.lastname: Nony
authors.forename: Aurore
authors.initials: A
authors.lastname: Gouraud
mesh_terms: D000368:Aged; D000889:Anti-Arrhythmia Agents / Q000009:adverse effects; D016022:Case-Control Studies; D062313:Databases, Pharmaceutical; D005260:Female; D005602:France / Q000453:epidemiology; D006299:Health Services for the Aged; D006801:Humans; D016015:Logistic Models; D008133:Long QT Syndrome / Q000139:chemically induced* / Q000150:complications; D008297:Male; D012189:Retrospective Studies; D016171:Torsades de Pointes / Q000150:complications / Q000453:epidemiology*
chemical_list: D000889:Anti-Arrhythmia Agents