Shift-work and cardiovascular disease: a population-based 22-year follow-up study

Area of Science:

• Occupational Health
• Cardiovascular Epidemiology
• Public Health

Background:

• Conflicting evidence exists regarding the association between shift work and cardiovascular disease (CVD).
• Previous studies have yielded inconsistent results on the impact of shift work on coronary heart disease (CHD) mortality, CVD-related disability retirement, and incident hypertension.

Purpose of the Study:

• To prospectively assess the association between shift work and three key cardiovascular endpoints.
• Investigate the relationship between shift work and CHD mortality, disability retirement due to CVD, and incident hypertension.

Main Methods:

• Prospective population-based study of 20,142 adults from the Finnish Twin Cohort (1982-2003).
• Shift work status assessed via questionnaires in 1975 and 1981.
• Cardiovascular endpoints ascertained from nationwide registers (mortality, disability, hypertension medication).
• Cox proportional hazard models used, with adjustments for 14 covariates and within twin pairs.

Main Results:

• No statistically significant hazard ratios (HRs) were observed for shift workers concerning CHD mortality, CVD disability retirement, or incident hypertension.
• HRs for shift work were not significant for men or women across all endpoints, even after comprehensive covariate adjustments.
• Analysis within twin pairs also revealed no association between shift work and the studied cardiovascular outcomes.

Conclusions:

• The study's findings do not support a significant association between shift work and increased cardiovascular morbidity or mortality.
• Shift work does not appear to be a significant risk factor for CHD mortality, CVD disability retirement, or hypertension in this cohort.
• Further research may be warranted, but current evidence from this large cohort does not link shift work to adverse cardiovascular outcomes.