title: Nighttime is associated with decreased survival and resuscitation efforts for out-of-hospital cardiac arrests: a prospective observational study.
abstract: BACKGROUND
  Whether temporal differences alter the clinical outcomes of patients with out-of-hospital cardiac arrest (OHCA) remains inconclusive. Furthermore, the relationship between time of day and resuscitation efforts is unknown.
  
  
  METHODS
  We studied adult OHCA patients in the Survey of Survivors after Out-of-Hospital Cardiac Arrest in the Kanto Region (SOS-KANTO) 2012 study from January 2012 to March 2013 in Japan. The primary variable was 1-month survival. The secondary outcome variables were prehospital and in-hospital resuscitation efforts by bystanders, emergency medical services personnel, and in-hospital healthcare providers. Daytime was defined as 0701 to 1500 h, evening was defined as 1501 to 2300 h, and night was defined as 2301 to 0700 h.
  
  
  RESULTS
  During the study period, 13,780 patients were included in the analysis. The patients with night OHCA had significantly lower 1-month survival compared to the patients with daytime OHCA (night vs. daytime, adjusted odds ratio (OR) 1.66; 95 % confidence interval (CI), 1.34-2.07; P < 0.0001). The nighttime OHCA patients had significantly shorter call-response intervals, bystander CPR, in-hospital intubation, and in-hospital blood gas analyses compared to the daytime and evening OHCA patients (call-response interval: OR 0.95 and 95 % CI 0.93-0.96; bystander CPR: OR 0.85 and 95 % CI 0.78-0.93; in-hospital intubation: OR 0.85 and 95 % CI 0.74-0.97; and in-hospital blood gas analysis: OR 0.86 and 95 % CI 0.75-0.98).
  
  
  CONCLUSIONS
  There was a significant temporal difference in 1-month survival after OHCA. The nighttime OHCA patients had significantly decreased resuscitation efforts by bystanders and in-hospital healthcare providers compared to those with evening and daytime OHCA.
authors.affiliation: Department of Emergency and Critical Care Medicine, Chiba University Graduate School of Medicine, 1-8-1 Inohana, Chuo-ku, Chiba City, Chiba, 260-8677, Japan.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Matsumura
authors.affiliation: Department of Emergency and Critical Care Medicine, Chiba University Graduate School of Medicine, 1-8-1 Inohana, Chuo-ku, Chiba City, Chiba, 260-8677, Japan. taka.nakada@nifty.com.
authors.forename: Taka-Aki
authors.initials: TA
authors.lastname: Nakada
authors.affiliation: Department of Emergency and Critical Care Medicine, Chiba University Graduate School of Medicine, 1-8-1 Inohana, Chuo-ku, Chiba City, Chiba, 260-8677, Japan.
authors.forename: Koichiro
authors.initials: K
authors.lastname: Shinozaki
authors.affiliation: Department of Emergency and Critical Care Medicine, Nippon Medical School Hospital, 1-1-5 Sendagi Bunkyo-ku, Tokyo, 113-0022, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Tagami
authors.affiliation: Department of Emergency and Critical Care Medicine, Juntendo University Nerima Hospital, 3-1-10 Takanodai, Nerima-ku, Tokyo, 177-0033, Japan.
authors.forename: Tomohisa
authors.initials: T
authors.lastname: Nomura
authors.affiliation: National Cerebral and Cardiovascular Center Hospital, 5-7-1 Fujishiro-dai, Suita, Osaka, 565-8565, Japan.
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Tahara
authors.affiliation: Division of Emergency and Critical Care Medicine, Department of Acute Medicine, Nihon University School of Medicine, 30-1 Oyaguchikamicho, Itabashi-ku, Tokyo, 173-0032, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Sakurai
authors.affiliation: Department of Biostatistics, Kyoto University School of Public Health, Kyoto, 606-8501, Japan.
authors.forename: Naohiro
authors.initials: N
authors.lastname: Yonemoto
authors.affiliation: Nihon University Surugadai Hospital, 1-6 Kanda-Surugadai, Chiyoda-ku, Tokyo, 101-8309, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Nagao
authors.affiliation: Department of Critical Care and Emergency Medicine, Tokyo Women's Medical University, 8-1 Kawadacho, Shinjuku-ku, Tokyo, 162-8666, Japan.
authors.forename: Arino
authors.initials: A
authors.lastname: Yaguchi
authors.affiliation: Department of Emergency Medicine, Yokohama City University Medical Center, 4 -57 Urafunecho, Minami-ku, Yokohama City, Kanagawa, 232-0024, Japan.
authors.forename: Naoto
authors.initials: N
authors.lastname: Morimura
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016887:Cardiopulmonary Resuscitation / Q000401:mortality* / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D058687:Out-of-Hospital Cardiac Arrest / Q000401:mortality*; D011446:Prospective Studies; D011795:Surveys and Questionnaires; D016019:Survival Analysis; D013997:Time Factors
keywords: Cardiopulmonary resuscitation; Circadian rhythm; Heart arrest; Out-of-hospital cardiac arrest; Resuscitation