title: Association of daylight saving time transitions with incidence and in-hospital mortality of myocardial infarction in Finland.
abstract: BACKGROUND
  Circadian rhythm disturbance increases cardiovascular risk but the effects of daylight saving time (DST) transitions on the risk of myocardial infarction (MI) are unclear.
  
  
  METHODS
  We studied association of DST transitions in 2001-2009 with incidence and in-hospital mortality of MI admissions nationwide in Finland. Incidence rations (IR) of observed incidences on seven days following DST transition were compared to expected incidences.
  
  
  RESULTS
  Incidence of MI increased on Wednesday (IR 1.16; CI 1.01-1.34) after spring transition (6298 patients' cohort). After autumn transition (8161 patients' cohort), MI incidence decreased on Monday (IR 0.85; CI 0.74-0.97) but increased on Thursday (IR 1.15; CI 1.02-1.30). The overall incidence of MI during the week after each DST transition did not differ from control weeks. Patient age or gender, type of MI or in-hospital mortality were not associated with transitions. Renal insufficiency was more common among MI patients after spring transition (OR 1.81; CI 1.06-3.09; p < 0.05). Diabetes was less common after spring transition (OR 0.71; CI 0.55-0.91; p = 0.007), but more common after autumn transition (OR 1.21; 1.00-1.46; p < 0.05).
  
  
  CONCLUSIONS
  DST transitions are followed by changes in the temporal pattern but not the overall rate of MI incidence. Comorbidities may modulate the effects DST transitions.
authors.affiliation: a Department of Neurology , North Karelia Central Hospital , Joensuu , Finland ;|b Department of Neurology , University of Turku , Turku , Finland ;|c Division of Clinical Neurosciences , Turku University Hospital , Turku , Finland ;
authors.forename: Jussi O T
authors.initials: JO
authors.lastname: Sipilä
authors.affiliation: d Clinical Research Center, Turku University Hospital , Turku , Finland ;|e Department of Public Health , University of Turku , Turku , Finland ;
authors.forename: Päivi
authors.initials: P
authors.lastname: Rautava
authors.affiliation: f Research Centre of Applied and Preventive Cardiovascular Medicine, University of Turku , Turku , Finland ;|g Heart Center, Turku University Hospital , Turku , Finland.
authors.forename: Ville
authors.initials: V
authors.lastname: Kytö
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002940:Circadian Rhythm; D005260:Female; D005387:Finland / Q000453:epidemiology; D017052:Hospital Mortality; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000453:epidemiology / Q000401:mortality*; D012189:Retrospective Studies; D012307:Risk Factors; D012621:Seasons
keywords: Acute coronary syndrome; chronobiology; circadian rhythm; circadian rhythm misalignment; daylight saving time; myocardial infarction; risk