title: Use of QT-prolonging medications in US emergency departments, 1995-2009.
abstract: OBJECTIVE
  Emergency department (ED) patients receive medications that place them at risk for adverse events, including drug-induced prolongation of the QT interval, which can lead to Torsade de Pointes and sudden cardiac death. We report the frequency of prescription and co-prescription of QT-prolonging medications in US EDs and factors associated with high-risk prescribing practices.
  
  
  METHODS
  We analyzed the ED component of the National Hospital Ambulatory Medical Care Survey for 1995 through 2009. Yearly rates of visits involving the prescription of QT-prolonging medications were determined. Multivariate regression analyses identified factors associated with the prescription of two or more QT-prolonging medications.
  
  
  RESULTS
  Approximately 16.5 million visits annually (15.0%) involved prescription of a QT-prolonging drug, with 1.7 million (1.6%) involving multiple prescriptions. Visits associated with QT-prolonging drugs more than doubled over the study period (10.4% to 22.2%). Diphenhydramine, azithromycin, and ondansetron were most frequently implicated (46.1% of cases). The most commonly prescribed combination was diphenhydramine and famotidine, both QT-prolonging medications available over-the-counter. Female gender and older age were associated with co-prescription of QT-prolonging medications. The rate of EKG screening among visits associated with QT-prolonging drug combinations was low (20.9%), but more common than among visits without a QT-prolonging drug (OR 1.3; 95% CI 1.2-1.5).
  
  
  CONCLUSIONS
  Use of QT-prolonging medications is increasing in EDs nationally. A small number of agents account for a large proportion of these visits and may represent an area for targeted screening or monitoring interventions in the ED.
authors.affiliation: Division of Emergency Medicine, Children's Hospital of Philadelphia, Philadelphia, PA, USA; Department of Pediatrics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: Khoon-Yen
authors.initials: KY
authors.lastname: Tay
authors.forename: Michele Burns
authors.initials: MB
authors.lastname: Ewald
authors.forename: Florence T
authors.initials: FT
authors.lastname: Bourgeois
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000553:Ambulatory Care / Q000639:trends*; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use*; D003625:Data Collection / Q000379:methods; D004363:Drug Utilization / Q000639:trends*; D004562:Electrocardiography / Q000639:trends; D004636:Emergency Service, Hospital / Q000639:trends*; D005260:Female; D006801:Humans; D008133:Long QT Syndrome / Q000175:diagnosis / Q000188:drug therapy* / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D014481:United States / Q000453:epidemiology; D055815:Young Adult
chemical_list: D000889:Anti-Arrhythmia Agents
keywords: QT-prolonging drug prescribing patterns; Torsade de Pointes; drug-induced QT prolongation; emergency department; pharmacoepidemiology