Following a first myocardial infarction (MI) event, people who return to working longer hours — 55 hours or more per week — are at an increased risk for experiencing recurrent coronary heart disease (CHD) events, according to research published in the Journal of the American College of Cardiology.1
Results of a recent systematic review suggest that longer working hours may be associated with incidence of CHD and stroke, an effect that may be higher in patients with preexisting cardiovascular conditions.2 Researchers then sought to examine the role that long working hours play in the risk for recurrent CHD in this population.1
Included participants (N=1191) were recruited from 30 hospitals in Quebec, Canada, between 1995 and 1997, had a history of an initial acute MI, were younger than 60 years of age, had a paid job in the 12 months prior to MI, and planned to return to work for at least 10 hours per week within 18 months of the MI.
Over the course of the study period, 205 participants experienced a recurrent CHD event, with an overall incidence rate of 3.60 cases per 100 person-years. Demographic data showed that men were overrepresented within the highest category of working hours (working ≥55 hours per week; 10.7% of men vs 1.9% of women). Younger workers who perceived themselves as having a financially comfortable economic situation were also proportionally overrepresented.
Patients in this category also had higher rates of CHD risk factors such as hypertension and diabetes; lifestyle habits, including smoking status, alcohol intake, and physical inactivity; and a more stressful work environment, including job strain and low support.
A descriptive Kaplan-Meier curve indicated that workers who were exposed to long hours had a higher risk for a recurrent CHD event. Results of an unadjusted analysis showed that long working hours — 55 hours or more per week vs 35 to 40 hours per week — were associated with a 2-fold increase in recurrent CHD risk (hazard ratio [HR], 2.00; 95% CI, 1.36-2.95). This association held in the fully adjusted model that controlled for sociodemographic, lifestyle-related, and clinical risk factors; work environment characteristics; and personality factors (HR, 1.67; 95% CI, 1.10-2.53).
Those who worked 55 hours or more per week who were also exposed to job strain had the highest risk, compared with those who worked 35 to 40 hours per week and who were not exposed to job-specific strain (HR, 2.55; 95% CI, 1.30-4.98), although the investigators note that this estimate was “imprecise.”
“To our knowledge, no previous study has examined the relationship between long working hours and the recurrence of CHD events,” the authors wrote. “This prospective cohort study showed that post-MI patients who worked long hours after their first event may have an increased risk of recurrent CHD events. Secondary prevention interventions…may lower the risk of CHD recurrence.”1
Limitations of this study include the small number of women participants and the measurement of long working hours at baseline only.
In an accompanying editorial, authors addressed the important implications of these study results for clinical practice, related in particular to the “provision of more comprehensive measures of secondary prevention” for people with CHD.3
The application of a short standardized assessment of patient working time and conditions could, the authors noted, “enrich physicians’ awareness of patients’ needs and inform medical decision making.” The European Society of Cardiology Cardiac Rehabilitation Section has proposed a set of potential screening questions that may be used to identify risk factors, especially those related to work stress, among at-risk patients.3
Another use for these research results might be the application of measures within cardiac rehabilitation programs to provide training skills related to coping with stressful demands and strengthening resilience. The inclusion of occupational health services to develop return-to-work plans may also be a positive step, although current evidence for the benefit of this type of intervention is weak.
Finally, the study authors suggested that these results could be used to push for “tailored measures in occupational settings” for patients with CHD who return to work.
“Occupational health services are urgently needed to be incorporated into cardiac rehabilitation programs and secondary prevention of CHD,” they concluded.3
1. Trudel X, Brisson C, Talbot D, Gilbert-Ouimet M, Milot A. Long working hours and risk of recurrent coronary events. J Am Coll Cardiol. 2021;77(13):1616-1625.doi:10.1016/j.jacc.2021.02.012
2. Kivimäki M, Jokela M, Nyberg ST, et al; IPD-Work Consortium. Long working hours and risk of coronary heart disease and stroke: a systematic review and meta-analysis of published and unpublished data for 603,838 individuals. Lancet. 2015;386(10005):1739-1746. doi:10.1016/S0140-6736(15)60295-1
3. Li J, Siegrist J. Occupational risks of recurrent coronary heart disease. J Am Coll Cardiol. 2021;77(13):1626-1628.doi:10.1016/j.jacc.2021.02.020