title: Long working hours and coronary heart disease: a systematic review and meta-analysis.
abstract: The authors aggregated the results of observational studies examining the association between long working hours and coronary heart disease (CHD). Data sources used were MEDLINE (through January 19, 2011) and Web of Science (through March 14, 2011). Two investigators independently extracted results from eligible studies. Heterogeneity between the studies was assessed using the I(2) statistic, and the possibility of publication bias was assessed using the funnel plot and Egger's test for small-study effects. Twelve studies were identified (7 case-control, 4 prospective, and 1 cross-sectional). For a total of 22,518 participants (2,313 CHD cases), the minimally adjusted relative risk of CHD for long working hours was 1.80 (95% confidence interval (CI): 1.42, 2.29), and in the maximally (multivariate-) adjusted analysis the relative risk was 1.59 (95% CI: 1.23, 2.07). The 4 prospective studies produced a relative risk of 1.39 (95% CI: 1.12, 1.72), while the corresponding relative risk in the 7 case-control studies was 2.43 (95% CI: 1.81, 3.26). Little evidence of publication bias but relatively large heterogeneity was observed. Studies varied in size, design, measurement of exposure and outcome, and adjustments. In conclusion, results from prospective observational studies suggest an approximately 40% excess risk of CHD in employees working long hours.
authors.affiliation: Finnish Institute of Occupational Health, Topeliuksenkatu 41 a A, FI-00250 Helsinki, Finland. marianna.virtanen@ttl.fi
authors.forename: Marianna
authors.initials: M
authors.lastname: Virtanen
authors.forename: Katriina
authors.initials: K
authors.lastname: Heikkilä
authors.forename: Markus
authors.initials: M
authors.lastname: Jokela
authors.forename: Jane E
authors.initials: JE
authors.lastname: Ferrie
authors.forename: G David
authors.initials: GD
authors.lastname: Batty
authors.forename: Jussi
authors.initials: J
authors.lastname: Vahtera
authors.forename: Mika
authors.initials: M
authors.lastname: Kivimäki
mesh_terms: D003327:Coronary Disease / Q000209:etiology*; D006801:Humans; D012306:Risk; D012307:Risk Factors; D014940:Work Schedule Tolerance; D016526:Workload