title: Shift work and vascular events: systematic review and meta-analysis.
abstract: OBJECTIVE
  To synthesise the association of shift work with major vascular events as reported in the literature.
  
  
  METHODS
  Systematic searches of major bibliographic databases, contact with experts in the field, and review of reference lists of primary articles, review papers, and guidelines.
  
  
  METHODS
  Observational studies that reported risk ratios for vascular morbidity, vascular mortality, or all cause mortality in relation to shift work were included; control groups could be non-shift ("day") workers or the general population.
  
  
  METHODS
  Study quality was assessed with the Downs and Black scale for observational studies. The three primary outcomes were myocardial infarction, ischaemic stroke, and any coronary event. Heterogeneity was measured with the I(2) statistic and computed random effects models.
  
  
  RESULTS
  34 studies in 2,011,935 people were identified. Shift work was associated with myocardial infarction (risk ratio 1.23, 95% confidence interval 1.15 to 1.31; I(2)=0) and ischaemic stroke (1.05, 1.01 to 1.09; I(2)=0). Coronary events were also increased (risk ratio 1.24, 1.10 to 1.39), albeit with significant heterogeneity across studies (I(2)=85%). Pooled risk ratios were significant for both unadjusted analyses and analyses adjusted for risk factors. All shift work schedules with the exception of evening shifts were associated with a statistically higher risk of coronary events. Shift work was not associated with increased rates of mortality (whether vascular cause specific or overall). Presence or absence of adjustment for smoking and socioeconomic status was not a source of heterogeneity in the primary studies. 6598 myocardial infarctions, 17,359 coronary events, and 1854 ischaemic strokes occurred. On the basis of the Canadian prevalence of shift work of 32.8%, the population attributable risks related to shift work were 7.0% for myocardial infarction, 7.3% for all coronary events, and 1.6% for ischaemic stroke.
  
  
  CONCLUSIONS
  Shift work is associated with vascular events, which may have implications for public policy and occupational medicine.
authors: Department of Epidemiology and Biostatistics, Western University, London, ON, Canada.
authors: Manav V
authors: MV
authors: Vyas
authors: Amit X
authors: AX
authors: Garg
authors: Arthur V
authors: AV
authors: Iansavichus
authors: John
authors: J
authors: Costella
authors: Allan
authors: A
authors: Donner
authors: Lars E
authors: LE
authors: Laugsand
authors: Imre
authors: I
authors: Janszky
authors: Marko
authors: M
authors: Mrkobrada
authors: Grace
authors: G
authors: Parraga
authors: Daniel G
authors: DG
authors: Hackam
mesh_terms: D002545:Brain Ischemia / Q000150:complications; D003327:Coronary Disease / Q000453:epidemiology* / Q000209:etiology / Q000517:prevention & control; D006801:Humans; D009203:Myocardial Infarction / Q000453:epidemiology* / Q000209:etiology / Q000517:prevention & control; D016017:Odds Ratio; D010561:Personnel Staffing and Scheduling; D018570:Risk Assessment; D012307:Risk Factors; D020521:Stroke / Q000453:epidemiology* / Q000209:etiology / Q000517:prevention & control; D014940:Work Schedule Tolerance