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Pharmacoepidemiol Drug Saf. 2014 Jan;23(1):9-17. doi: 10.1002/pds.3455. Epub 2013 May 21.

Use of QT-prolonging medications in US emergency departments, 1995-2009.

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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.



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.


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.


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).


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.


QT-prolonging drug prescribing patterns; Torsade de Pointes; drug-induced QT prolongation; emergency department; pharmacoepidemiology

[Indexed for MEDLINE]

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