Long working hours Increase Risk of Recurrent Coronary Events, Finds Study
Cardiovascular disease (CVD) is the leading cause of death worldwide. The identification of new preventive measures is a priority to reduce the burden of these diseases. In a recent study, researchers have found that long working hours increase the risk of the second attack in patients with a history of previous Myocardial Infarction (MI). The research has been published in the Journal of the American College of Cardiology on March 28, 2021.
Long working hours are frequent. According to the International Labour Office, approximately 1 in 5 workers worldwide work over 48 h/week, representing more than 614 million people. Evidence from prospective studies has suggested that long working hours are associated with incident coronary heart disease (CHD) events. However, no previous study has examined whether long working hours are associated with an increased risk of recurrent CHD events. Therefore, researchers of the Université Laval, Québec, Canada conducted a study to examine the effect of long working hours on the risk of recurrent CHD among patients returning to work after a first myocardial infarction (MI).
It was a prospective cohort study of 967 men and women age 35 to 59 years who returned to work after a first MI. Researchers recruited 30 hospitals across the province of Quebec, Canada and followed them for 5.9 years. They assessed the long working hours on average of 6 weeks after their return to work. They determined incident CHD events (fatal or nonfatal MI and unstable angina) during follow-up using patients' medical files.
They categorized patients based on their total weekly working hours:
♦ Part-time (21-34 hours per week; event rate: 2.77 per 100 person-years),
♦ Full time (35-40 hours per week; event rate: 3.48 per 100 person-years),
♦ Low overtime (41-54 hours per week; event rate: 3.27 per 100 person-years) and
♦ Medium/high overtime (55 hours per week; event rate: 7.05 per 100-person years).
Key findings of the study were:
- The researchers noted overall, 205 patients had recurrent CHD events.
- They found that patients working long hours (≥55 h/week) had a higher risk of recurrent CHD events after controlling for sociodemographics, lifestyle-related risk factors, clinical risk factors, work environment factors, and personality factors (hazard ratio vs 35 to 40 h/week: 1.67).
- The authors wrote, "These results showed a linear risk increase after 40 h/week and a stronger effect after the first 4 years of follow-up and when long working hours are combined with job strain."
They concluded, "Among patients returning to work after a first MI, longer working hours per week is associated with an increased risk of recurrent CHD events. Secondary prevention interventions aiming to reduce the number of working hours among these patients may lower the risk of CHD recurrence."
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