Objectives Long working hours may be associated with cardiovascular disease (CVD). The objective was to investigate cross-sectional associations of work hours with carotid intima–media thickness (CIMT) and ankle–brachial index (ABI).
Methods Participants were 1694 women and 1868 men from the Multi-Ethnic Study of Atherosclerosis. CIMT and ABI were measured using standard protocols. Information on work hours was obtained from questionnaires. Mean values of CIMT and ABI were examined across five categories of hours worked per week (≤20, 21–39, 40, 41–50 and >50) using analysis of variance/analysis of covariance. p Values for trend were obtained from linear regression models.
Results Mean age of participants was 56.9±8.4 years; 52.4% were men. Distinct patterns of association between work hours and the subclinical CVD biomarkers were found for women and men, although this heterogeneity by gender was not statistically significant. Among women only, work hours were positively associated with common (but not internal) CIMT (p=0.073) after full risk factor adjustment. Compared with women working 40 h, those working >50 h were more likely to have an ABI <1 (vs 1–1.4) (OR=1.85, 95% CI 1.01 to 3.38). In men, work hours and ABI were inversely associated (p=0.046). There was some evidence that the association between work hours and ABI was modified by occupational category (interaction p=0.061). Among persons classified as management/professionals, longer work hours was associated with lower ABI (p=0.015). No significant associations were observed among other occupational groups.
Conclusions Working longer hours may be associated with subclinical CVD. These associations should be investigated using longitudinal studies.
- carotid artery stenosis
- ankle–brachial index
- general expertise
- public health
- organ system
- disease type
- back disorders
- race and ethnicity issues
- organisation of work
- exposure assessment
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The Multi-Ethnic Study of Atherosclerosis (MESA) is conducted and supported by the National Heart, Lung, and Blood Institute in collaboration with MESA investigators. This manuscript has been reviewed by the MESA investigators for scientific content and consistency of data interpretation with previous MESA publications, and significant comments have been incorporated prior to submission for publication.
Funding MESA is supported by contracts N01-HC-95159 through N01-HC-95169 from the National Heart, Lung, and Blood Institute. Occupational coding was supported by the National Institute for Occupational Safety and Health (NORA FY08 CRN SLB8).
Disclaimer The findings and conclusions in this article are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health.
Competing interests None.
Patient consent Obtained.
Ethics approval Ethics approval was provided by the Institutional Review Boards of the National Heart, Lung, and Blood Institute, the six MESA field Centers and the National Institute for Occupational Safety and Health.
Provenance and peer review Not commissioned; externally peer reviewed.