title: Likelihood of acute coronary syndrome in emergency department chest pain patients varies with time of presentation.
abstract: BACKGROUND
  There is a circadian and circaseptal (weekly) variation in the onset of acute coronary syndrome (ACS). The aim of this study was to elucidate whether the likelihood of ACS among emergency department (ED) chest pain patients varies with the time of presentation.
  
  
  METHODS
  All patients presenting to the Lund ED at Skåne University Hospital with chest pain or discomfort during 2006 and 2007 were retrospectively included. Age, sex, arrival time at the ED and discharge diagnose (ACS or not) were obtained from the electronic medical records.
  
  
  RESULTS
  There was a clear but moderate circadian variation in the likelihood of ACS among presenting chest pain patients, the likelihood between 8 and 10 am being almost twice as high as between 6 and 8 pm. This was mainly explained by a variation in the ACS likelihood in females and patients under 65 years, with no significant variation in males and patients over 65 years. There was no significant circaseptal variation in the ACS likelihood.
  
  
  CONCLUSIONS
  Our results indicate that there is a circadian variation in the likelihood of ACS among ED chest pain patients, and suggest that physicians should consider the time of presentation to the ED when determining the likelihood of ACS.
authors.affiliation: Department of Emergency Medicine, Skåne University Hospital, Lund, SE-221 85, Sweden. ulf.ekelund@med.lu.se
authors.forename: Ulf
authors.initials: U
authors.lastname: Ekelund
authors.forename: Mahin
authors.initials: M
authors.lastname: Akbarzadeh
authors.forename: Ardavan
authors.initials: A
authors.lastname: Khoshnood
authors.forename: Jonas
authors.initials: J
authors.lastname: Björk
authors.forename: Mattias
authors.initials: M
authors.lastname: Ohlsson
mesh_terms: D054058:Acute Coronary Syndrome / Q000150:complications* / Q000175:diagnosis* / Q000503:physiopathology; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002637:Chest Pain / Q000150:complications*; D002940:Circadian Rhythm / Q000502:physiology; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D012189:Retrospective Studies; D012737:Sex Factors; D013997:Time Factors; D055815:Young Adult