title: Impact of seasonal temperature environment on the neurologic prognosis of out-of-hospital cardiac arrest: a nationwide, population-based cohort study.
abstract: OBJECTIVE
  The relationship between environmental factors, such as winter or cold environments, and the onset of out-of-hospital cardiac arrest (OHCA) is well known. However, the association between environmental factors and the neurologic outcome of OHCA is poorly understood. This study aimed to assess the impact of the ambient temperature on the neurologic outcome of adult OHCA.
  
  
  METHODS
  In a nationwide, population-based, observational study, we enrolled 121,081 adults 18 years or older who experienced an OHCA from January 1, 2010, to December 31, 2010. We used the All-Japan Utstein Registry database coupled with climate statistics data from the Japan Meteorological Agency. The primary end point was favorable neurologic outcome 1 month after OHCA.
  
  
  RESULTS
  Of the eligible 120,721 adult patients with OHCA, 7747 cases of OHCA (6.4%) occurred during the cold season, 80,739 (66.9%) occurred during the midseason, and 32,235 (26.7%) occurred during the warm season. The adults who experienced an OHCA during the cold season exhibited a significantly lower rate of a favorable neurologic outcome than did those who experienced an OHCA during the warm season (2.4% vs 3.3%; odds ratio, 0.73; 95% confidence interval, 0.62-0.85; P < .0001). The adjusted odds ratio for favorable neurologic outcome per 1°C increase in the monthly ambient temperature was 1.006 (95% confidence interval, 1.002-1.010; P = .0080).
  
  
  CONCLUSIONS
  The seasonal ambient temperature is likely to affect favorable neurologic outcome. A lower seasonal ambient temperature may exacerbate the neurologic outcome of OHCA.
authors.affiliation: Department of Emergency and Critical Care Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 1138655, Japan. Electronic address: tatsumafukuda-jpn@umin.ac.jp.
authors.forename: Tatsuma
authors.initials: T
authors.lastname: Fukuda
authors.affiliation: Department of Emergency and Critical Care Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 1138655, Japan.
authors.forename: Naoko
authors.initials: N
authors.lastname: Ohashi
authors.affiliation: Department of Emergency and Critical Care Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 1138655, Japan.
authors.forename: Kent
authors.initials: K
authors.lastname: Doi
authors.affiliation: Department of Emergency and Critical Care Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 1138655, Japan.
authors.forename: Takehiro
authors.initials: T
authors.lastname: Matsubara
authors.affiliation: Department of Emergency and Critical Care Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 1138655, Japan.
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Kitsuta
authors.affiliation: Department of Emergency and Critical Care Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 1138655, Japan.
authors.forename: Susumu
authors.initials: S
authors.lastname: Nakajima
authors.affiliation: Department of Emergency and Critical Care Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 1138655, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Yahagi
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001831:Body Temperature / Q000502:physiology; D002561:Cerebrovascular Disorders / Q000453:epidemiology* / Q000209:etiology; D015331:Cohort Studies; D003080:Cold Temperature / Q000009:adverse effects*; D004632:Emergency Medical Services; D004837:Epinephrine / Q000008:administration & dosage; D005260:Female; D006358:Hot Temperature / Q000009:adverse effects*; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D058687:Out-of-Hospital Cardiac Arrest / Q000453:epidemiology* / Q000209:etiology / Q000401:mortality; D011379:Prognosis; D012621:Seasons
chemical_list: D004837:Epinephrine
keywords: Cold temperature; Environment and public health; Out-of-hospital cardiac arrest