title: Circadian, weekly, and seasonal mortality variations in out-of-hospital cardiac arrest in Japan: analysis from AMI-Kyoto Multicenter Risk Study database.
abstract: 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.
  
  
  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.
  
  
  CONCLUSIONS
  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.
authors: Department of Cardiovascular Medicine, Kyoto Prefectural University of Medicine, Kyoto, Japan. naka-nao@koto.kpu-m.ac.jp
authors: Naohiko
authors: N
authors: Nakanishi
authors: Shinya
authors: S
authors: Nishizawa
authors: Yohei
authors: Y
authors: Kitamura
authors: Takeshi
authors: T
authors: Nakamura
authors: Akiyoshi
authors: A
authors: Matsumuro
authors: Takahisa
authors: T
authors: Sawada
authors: Hiroaki
authors: H
authors: Matsubara
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016009:Chi-Square Distribution; D002940:Circadian Rhythm; D016208:Databases, Factual; D005260:Female; D006801:Humans; D015994:Incidence; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D058687:Out-of-Hospital Cardiac Arrest / Q000453:epidemiology / Q000401:mortality*; D011446:Prospective Studies; D012307:Risk Factors; D012621:Seasons; D018709:Statistics, Nonparametric; D017180:Tachycardia, Ventricular / Q000453:epidemiology / Q000401:mortality; D013696:Temperature; D013997:Time Factors; D014693:Ventricular Fibrillation / Q000453:epidemiology / Q000401:mortality