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Emergency medicine
Research
Association between QTc prolongation and mortality in patients with suspected poisoning in the emergency department: a transnational propensity score matched cohort study
  1. Camilla Schade Hansen1,
  2. Anton Pottegård2,
  3. Ulf Ekelund3,
  4. Helene Kildegaard Jensen1,
  5. Jakob Lundager Forberg4,
  6. Mikkel Brabrand1,5,
  7. Annmarie Touborg Lassen1
  1. 1 Department of Emergency Medicine, Odense University Hospital, Odense, Denmark
  2. 2 Clinical Pharmacology and Pharmacy, Department of Public Health, University of Southern Denmark, Odense, Denmark
  3. 3 Department of Emergency Medicine, Skåne University Hospital, Lund, Sweden
  4. 4 Department of Emergency Medicine, Helsingborg Hospital, Helsingborg, Sweden
  5. 5 Department of Emergency Medicine, Hospital of South West Jutland, Esbjerg, Denmark
  1. Correspondence to Camilla Schade Hansen; camilla.schade.hansen{at}rsyd.dk

Abstract

Objectives Poisoning is a frequent cause of admission to the emergency department (ED) and may involve drugs known to prolong the QT interval. This study aims to describe the prevalence of QTc prolongation among ED patients with suspected poisoning and to calculate the absolute and relative risk of mortality or cardiac arrest associated with a prolonged QTc interval.

Methods We performed a register-based cohort study, including all adult first-time contacts with suspected poisoning to the ED of two Swedish hospitals (January 2010–December 2014) and two Danish hospitals (March 2013–April 2014). We used propensity score matching to calculate HRs for all-cause mortality or cardiac arrest (combined endpoint) within 30 days after contact comparing patients with a prolonged QTc interval (≥450 ms men, ≥460 ms women) with patients with a QTc interval of <440 ms.

Results Among all first-time contacts with suspected poisoning that had an ECG recorded within 4 hours after arrival (n=3869), QTc prolongation occurred in 6.5%. The overall mortality after a 30-day follow-up period was 0.8% (95% CI 0.6 to 1.2), with an absolute risk of mortality or cardiac arrest in patients with QTc prolongation of 3.2% (95% CI 1.4 to 6.1). A prolonged QTc interval on arrival was associated with a HR of 3.6 (95% CI 1.0 to 12.2).

Conclusion In the ED, a prolonged QTc interval in patients arriving with suspected poisoning seems to be associated with a threefold increased risk of 30-day all-cause mortality or cardiac arrest.

  • epidemiology
  • cardiology
  • toxicology

This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/

https://doi.org/10.1136/bmjopen-2017-020036

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    Footnotes

    • Contributors CSH designed the study, interpreted the results and drafted the paper. AP analysed the data. All authors conceived the study. ATL, AP and HKJ provided statistical advice and advice on the study design. AP, ATL, HKJ, UE, MB, and JLF critically reviewed the paper, assisted with interpretation of the results and have approved the final edition. CSH takes responsibility for the final paper.

    • Funding This study was funded by an independent grant from The Research Foundation of Odense University Hospital.

    • Disclaimer The funding sources had no role in the design of the study, data analysis or interpretation of the results.

    • Competing interests ATL was supported by an unrestricted grant to the University of Southern Denmark from TrygFoundation.

    • Patient consent Not required.

    • Ethics approval In consistency with Swedish law the study was approved by the Regional Ethics Committee in Lund and by Region Skåne.

    • Provenance and peer review Not commissioned; externally peer reviewed.

    • Data sharing statement Due to Danish law regarding personal data, we are not allowed to share data in public dataset. However, we welcome every researcher who wants to repeat the analysis or do new analysis in the dataset. Please contact professor Annmarie Lassen (Annmarie.Lassen@rsyd.dk), and she will help the researcher to get access to the data.