University of Oulu

Ryti NRI, Mäkikyrö EMS, Antikainen H, et al Risk of sudden cardiac death in relation to season-specific cold spells: a case–crossover study in Finland BMJ Open 2017;7:e017398. doi: 10.1136/bmjopen-2017-017398

Risk of sudden cardiac death in relation to season-specific cold spells : a case–crossover study in Finland

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Author: Ryti, Niilo R I1; Mäkikyrö, Elina M S1; Antikainen, Harri2;
Organizations: 1Center for Environmental and Respiratory Health Research (CERH), Faculty of Medicine, University of Oulu, Oulu, Finland
2Department of Geography, University of Oulu, Oulu, Finland
3Department of Research Unit of Internal Medicine, Medical Research Center Oulu, Oulu University Hospital, Oulu, Finland
4Department of Forensic Medicine, University of Oulu, Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 0.4 MB)
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Language: English
Published: BMJ, 2017
Publish Date: 2019-05-20


Objective: To test a priori hypothesis of an association between season-specific cold spells and sudden cardiac death (SCD).

Methods: We conducted a case–crossover study of 3614 autopsy-verified cases of SCD in the Province of Oulu, Finland (1998–2011). Cold spell was statistically defined by applying an individual frequency distribution of daily temperatures at the home address during the hazard period (7 days preceding death) and 50 reference periods (same calendar days of other years) for each case using the home coordinates. Conditional logistic regression was applied to estimate ORs for the association between the occurrence of cold spells and the risk of SCD after controlling for temporal trends.

Results: The risk of SCD was associated with a preceding cold spell (OR 1.33; 95% CI 1.00, 1.78). A greater number of cold days preceding death increased the risk of SCD approximately 19% per day (OR 1.19; 95% CI 1.07 to 1.32). The association was strongest during autumn (OR 2.51; 95% CI 1.27 to 4.96) and winter (OR 1.70; 95% CI 1.13 to 2.55) and lowest during summer (OR 0.42; 95% CI 0.15 to 1.18) and spring (OR 0.89; 95% CI 0.45 to 1.79). The association was stronger for ischaemic (OR 1.55; 95% CI 1.12 to 2.13) than for non-ischaemic SCD (OR 0.68; 95% CI 0.32 to 1.45) verified by medicolegal autopsy.

Conclusions: Our results indicate that there is an association between cold spells and SCD, that this association is strongest during autumn, when the weather event is prolonged, and with cases suffering ischaemic SCD. These findings are subsumed with potential prevention via weather forecasting, medical advice and protective behaviour.

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Series: BMJ open
ISSN: 2044-6055
ISSN-E: 2044-6055
ISSN-L: 2044-6055
Volume: 7
Article number: e017398
DOI: 10.1136/bmjopen-2017-017398
Type of Publication: A1 Journal article – refereed
Field of Science: 3121 General medicine, internal medicine and other clinical medicine
3142 Public health care science, environmental and occupational health
Copyright information: © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted. 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: