The International Labour Office reports that approximately 20% of workers worldwide work >48 hours per week. Research suggests an association between long working hours and incident coronary heart disease (CHD) events. No studies have explored if the same association exists between long working hours and subsequent CHD events. Prof. Xavier Trudel and his team conducted a prospective cohort study of 967 men and women between the ages of 35 and 59 years to examine this relationship. Participants were recruited from 30 hospitals located in the province of Quebec, Canada.
After a mean follow-up period of 5.9 years following an index CHD event, 205 (21.2%) participants experienced recurrent CHD events. Participants working long hours (≥55 hours per week) demonstrated an increased risk of experiencing a secondary CHD event. The risk of a secondary CHD event increased linearly beyond working >40 hours per week. This association remained after controlling for sociodemographic, lifestyle, and clinical risk factors, as well as work environment and personality factors (hazard ratio vs. 35 to 40 hours per week: 1.67; 95% confidence interval: 1.10 to 2.53). Researchers noted that the magnitude of this effect is comparable to the risk for CHD associated with smoking.
The onset of an identifiable cardiac event may only occur after prolonged exposure to risk factors. In the present study, the effect was stronger following the first 4 years of follow-up. The effect was also stronger in situations in which job strain was combined with long working hours.
There were men than women in the long hours working group (10.7% of all men vs. 1.9% of all women), and more workers of a younger age. Participants working longer hours tended to have more CHD and lifestyle risk factors (hypertension, diabetes, smoking, alcohol consumption and physical inactivity).
Researchers call for the identification of secondary prevention measures to prevent secondary CHD events and reduce the burden of cardiovascular disease. They suggest that number of working hours should be part of routine follow-up questioning in an attempt to reduce the risk of subsequent CHD events in post-MI patients.
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Author: Kelly Schoonderwoerd
Original article: Trudel et al. J Am Coll Cardiol. 2021 Apr 6;77(13):1616-1625.