Working night shift linked to heart disease

Editor's Note

Female RNs working a rotating night shift for 5 years or more was associated with a statistically significant increased risk of coronary heart disease (CHD) in this study.

The analysis included nearly 190,000 RNs involved in the Nurses’ Health Studies (NHS), who were followed over 24 years in the NHS (1988-2012) and NHS2 (1989-2013).

Compared with women in the NHS, those in NHS2 were younger, nulliparous, had lower alcohol consumption, reported fewer pack-years of smoking, had fewer comorbid conditions, and took fewer medications and multivitamin supplements.

During follow-up, 7,303 incidents of CHD occurred in the NHS and 3,519 incidents occurred in the younger NHS2.

In the NHS, the association between duration of shift work and CHD was stronger in the first half of follow-up than in the second half, suggesting a lowering of risk after stopping shift work.

Longer time after stopping shift work was associated with decreased CHD risk in the NHS2.

In both cohorts, biennial questionnaires were used to collect information on medical history, anthropometric data, diet, and lifestyle. Most variables were updated biennially from baseline onward; physical activity and dietary data were obtained approximately every 4 years.