Objectives Men with high physical work demands have elevated cardiovascular strain, which may lead to enhanced atherosclerosis. Theoretically, the impact of risk factors for ischaemic heart disease (IHD) may thus depend on physical work demands. The authors investigated this hypothesis.
Design Prospective 30-year follow-up.
Setting The Copenhagen Male Study.
Participants 5249 gainfully employed men aged 40–59 years; 311 men with cardiovascular disease/diabetes were excluded.
Primary and secondary outcome measures IHD and all-cause mortality.
Results 579 men (11.8%) died due to IHD and 2628 (53.7%) from all-cause mortality. Similarities and differences in risk predictors were found between men with low (n=1219), medium (n=2636) and high (n=846) physical work demands. After control for potential confounders, high physical fitness conferred a reduced risk of IHD mortality only among men with high physical work demands (HR: 0.48, 95% CI 0.24 to 0.96), a moderate/high level of leisure-time physical activity was associated with reduced risk of IHD mortality only among men with moderate and high physical work demands. High systolic blood pressure and smoking were risk factors in all groups. Similar, but less pronounced differences in risk factors for all-cause mortality between groups were found.
Conclusions The risk factors for IHD and all-cause mortality, low physical fitness and low leisure-time physical activity are not identical for men with different physical work demands. Preventive initiatives for IHD should be tailored to the physical work demands.
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Original study protocol It does not exist.
To cite: Holtermann A, Mortensen OS, Søgaard K, et al. Risk factors for ischaemic heart disease mortality among men with different occupational physical demands. A 30-year prospective cohort study. BMJ Open 2012;2:e000279. doi:10.1136/bmjopen-2011-000279
Funding The study is a part of the physical work demands and fitness project, financed by the Danish Working Environment Research Foundation.
Competing interests None.
Ethics approval When the Copenhagen Male Study (CMS) was initiated as a closed cohort study in 1970–1971, no ethics committee for medical research had been established in Denmark. However, in 1985–1986, when survivors from the first baseline were re-examined, the study was approved by the ethics committee for medical research in the county of Copenhagen, and all participants in the study gave informed consent to participate, as stated in many previous publications from the CMS based on analyses using the 1985–1986 baseline.
Contributors All authors contributed to the conception, design, interpretation of data and writing or critically revising the manuscript. PS made the statistical analyses. AH and PS are guarantors.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement Technical appendix and statistical code available from the corresponding author at . Consent was not obtained, but the presented data are anonymised, and risk of identification is very low. No additional data available.
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