Long Work Hours Are Associated with Excess Risk for Coronary Heart Disease and Stroke

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Bruce Soloway, MD reviewing Kivimäki M et al. Lancet 2015 Aug 19.

Encouraging or requiring people to work longer hours could have substantial public health implications.

Two meta-analyses of published cohort studies have suggested that long working hours lead to excess risk for coronary heart disease (CHD). To explore this hypothesis further, researchers combined data from 25 prospective cohort studies from Europe, the U.S., and Australia that included data on working hours and incident CHD or stroke. The resulting data sets included more than 600,000 people who were followed for a mean 8.5 years for CHD and more than 500,000 people who were followed for a mean 7.2 years for stroke.

Compared with standard working hours (35–40 hours weekly), and after adjustment for age, sex, and socioeconomic status, long working hours (>55 hours weekly) were associated significantly with higher risk for incident CHD (relative risk, 1.13) and stroke (RR, 1.33). Risk for incident stroke increased linearly as working hours increased; no such dose-response relation was seen for CHD. Excess risk for CHD with longer working hours was more pronounced in patients with low than with high socioeconomic status; no other significant subgroup differences were found.