Shiftwork and mortality from ischaemic heart disease

Area of Science:

• Occupational Health
• Cardiovascular Epidemiology
• Industrial Hygiene

Background:

• Shift work is common in many industries, raising concerns about potential long-term health effects.
• Ischaemic heart disease (IHD) remains a leading cause of mortality worldwide.
• Understanding the relationship between occupational exposures like shift work and cardiovascular outcomes is crucial for public health.

Purpose of the Study:

• To investigate the association between shift work and mortality from ischaemic heart disease (IHD).
• To determine if prolonged or intermittent shift work influences the risk of dying from IHD.
• To explore potential confounding factors and effect modification in this relationship.

Main Methods:

• A nested case-control study design was employed within a cohort of male manual workers.
• Cases were defined as deaths from IHD (ICD 410-414) among cohort members aged 75 or under.
• Work status (shift vs. day work) was determined from historical personnel records, with adjustments for covariates like BMI, blood pressure, and smoking.

Main Results:

• No overall increased risk of IHD death was found associated with shift work.
• A reduced risk of IHD death was observed during active periods of shift work.
• An increased risk of IHD death was noted in the first five years after transitioning from shift work to day work.

Conclusions:

• Shift work itself does not appear to elevate the risk of death from ischaemic heart disease in this cohort.
• Health-related selection may lead to underrepresentation of individuals with poorer cardiovascular health among long-term shift workers.
• The findings suggest a complex interplay between shift work, cardiovascular health, and occupational transitions.