title: Within-summer variation in out-of-hospital cardiac arrest due to extremely long sunshine duration.
abstract: BACKGROUND
  Although several studies have reported the impacts of extremely high temperatures on cardiovascular diseases, no studies have examined whether variation in out-of-hospital cardiac arrest (OHCA) due to extremely long sunshine duration changes during the summer.
  
  
  METHODS
  We obtained daily data on all cases of OHCA and weather variations for all 47 prefectures of Japan during the summer (June to September) between 2005 and 2014. A distributed lag non-linear model combined with a quasi-Poisson regression model was used to estimate within-summer variation in OHCA due to extremely long sunshine duration for each prefecture. Then, multivariate random-effects meta-analysis was performed to derive overall effect estimates of sunshine duration at the national level.
  
  
  RESULTS
  A total of 166,496 OHCAs of presumed cardiac origin met the inclusion criteria. The minimum morbidity percentile (MMP) was the 0th percentile of sunshine duration at the national level. The overall cumulative relative risk (RR) at the 99th percentile vs. the MMP was 1.15 (95% CI: 1.05-1.27) during the summer. The effect of extremely long sunshine duration on OHCA in early summer was acute and did not persist, whereas an identical effect was observed in late summer, but it was delayed and lasted for several days.
  
  
  CONCLUSIONS
  During summer periods, excessive sunshine duration could increase the risk of OHCA. Timely preventive measures to reduce the OHCA risk due to extremely long sunshine duration are important in early summer, whereas these measures could include a wider time window of several days to reduce the risk in late summer.
authors.affiliation: Department of Health Communication, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan. Electronic address: onozukad@hcam.med.kyushu-u.ac.jp.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Onozuka
authors.affiliation: Department of Health Communication, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan. Electronic address: hagihara@hsmp.med.kyushu-u.ac.jp.
authors.forename: Akihito
authors.initials: A
authors.lastname: Hagihara
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005500:Follow-Up Studies; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008875:Middle Aged; D009017:Morbidity / Q000639:trends; D058687:Out-of-Hospital Cardiac Arrest / Q000453:epidemiology / Q000209:etiology*; D012189:Retrospective Studies; D018570:Risk Assessment / Q000379:methods*; D012621:Seasons; D013472:Sunlight / Q000009:adverse effects*; D013997:Time Factors; D055815:Young Adult
keywords: Cardiac arrest; Environmental medicine; Epidemiology; Statistical analysis; Sudden death; Sunshine