Ugeskrift for laegerApr 15, 2000

Shift Work, Social Class, and Risk of Heart Disease in Middle-Aged and Older Men Over 22 Years

Circadian Biology Weekly Brief ↗PubMed ↗

Updated Apr 6, 2026

Abstract

The adjusted relative risk for ischaemic heart disease in shift workers was 0.9.

No significant difference in the risk of ischaemic heart disease was found between shift and day workers.
Adjusted relative risk estimates for ischaemic heart disease were 0.9 (0.7-1.1) overall.
Restriction to social class III resulted in an adjusted relative risk of 0.7 (0.5-1.0).
The findings do not support the idea that shift work is an independent risk factor for ischaemic heart disease.
The relationship between shift work and ischaemic heart disease remains a topic of debate.

Simplified

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.

Shift Work, Social Class, and Risk of Heart Disease in Middle-Aged and Older Men Over 22 Years

Abstract

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