[Shift work, social class and ischemic heart disease in middle-aged and elderly men. A 22-year follow-up in the "Copenhagen Male Study"].
Shift work has been reported as a risk factor for ischaemic heart disease. Most studies have only partly controlled for social class differences, a recognized risk factor for ischaemic heart disease (IHD), and the relative risk of 1.4 could be a result of confounding. The Copenhagen Male Study was established in 1971 as a prospective cohort study of 5,249 men, and included questions on working time, social class and other potential confounders. The cohort was followed through registers for 22 years. Risk of IHD and all cause mortality did not differ between shift and day workers, the adjusted relative risk for IHD being 0.9 (0.7-1.1). Restriction to social class III led to lower risk estimates, with an adjusted relative risk of 0.7 (0.5-1.0). The study gave no support to the hypothesis that shift work is an independent risk factor for IHD. The role of shift work as an independent risk factor for IHD is still controversial.
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Aalborg Sygehus, Center for Arbejdstidsforskning, arbejdsmedicinsk klinik. hb@aas.nja.dk
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D000368:Aged; D002423:Cause of Death; D015331:Cohort Studies; D003327:Coronary Disease / Q000209:etiology* / Q000401:mortality / Q000523:psychology; D003718:Denmark / Q000453:epidemiology; D005500:Follow-Up Studies; D006801:Humans; D008019:Life Style; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000209:etiology* / Q000401:mortality / Q000523:psychology; D011446:Prospective Studies; D012307:Risk Factors; D020178:Sleep Disorders, Circadian Rhythm / Q000150:complications; D012923:Social Class; D014940:Work Schedule Tolerance / Q000502:physiology / Q000523:psychology