Circadian, weekly, and seasonal mortality variations in out-of-hospital cardiac arrest in Japan: analysis from AMI-Kyoto Multicenter Risk Study database

Am J Emerg Med. 2011 Nov;29(9):1037-43. doi: 10.1016/j.ajem.2010.06.018. Epub 2010 Aug 13.


Background: Several studies have reported circadian, weekly, and seasonal variations in the rates of out-of-hospital cardiac arrest (OHCA). However, variations in the mortality of OHCA are not well known.

Methods and results: We investigated the 1396 consecutive cases of OHCA with cardiac etiology between October 2004 and September 2008. There were 2 peaks in the occurrence of OHCA in early morning and late evening. There was a weekly pattern with an increased incidence on Mondays. We found a significant seasonal variation in the frequency of events, with a maximum during winter. There was a trend of reduced mortality in warmest 3 months, especially among a subgroup of ventricular fibrillation/pulseless ventricular tachycardia with arrest witnessed.

Conclusion: The present analyses demonstrated circadian, weekly and seasonal variations in the occurrence, and a seasonal variation in mortality in OHCA. Changes in temperature might influence the severity of OHCA and change the rate of success of cardiopulmonary resuscitation.

Publication types

  • Multicenter Study

MeSH terms

  • Aged
  • Aged, 80 and over
  • Chi-Square Distribution
  • Circadian Rhythm
  • Databases, Factual
  • Female
  • Humans
  • Incidence
  • Japan / epidemiology
  • Male
  • Middle Aged
  • Out-of-Hospital Cardiac Arrest / epidemiology
  • Out-of-Hospital Cardiac Arrest / mortality*
  • Prospective Studies
  • Risk Factors
  • Seasons
  • Statistics, Nonparametric
  • Tachycardia, Ventricular / epidemiology
  • Tachycardia, Ventricular / mortality
  • Temperature
  • Time Factors
  • Ventricular Fibrillation / epidemiology
  • Ventricular Fibrillation / mortality