Cumulative Exposure to Long Working Hours and Occurrence of Ischemic Heart Disease: Evidence From the CONSTANCES Cohort at Inception

Background Long‐working hours (LWH ) are a probable risk factor for ischemic heart diseases (IHD ); however, no previous study has considered duration of exposure toLWH when addressing this topic. We aimed to determine the association between cumulative exposure toLWH andIHD while accounting for relevant confounders.Methods and Results In this retrospective study, we included all baseline participants from the French population‐based cohortCONSTANCES . Part‐time employees and those who reported a cardiac event in the 5 years beforeLWH exposure were excluded. From self‐administered questionnaires and clinical examinations, we obtained participants’ age, sex, body mass index, occupational status, smoking habits, high blood pressure, diabetes mellitus, familial history of cardiovascular disease, dyslipidemia, exposure toLWH , and its duration. We definedLWH as working for >10 hours daily for at least 50 days per year. The main outcome was reported history ofIHD , ie, myocardial infarction or angina pectoris, during a clinical examination. Of 137 854 included participants, 69 774 were men. There were 1875 cases (1.36%) ofIHD , and exposure toLWH was reported by 42 462 subjects (30.8%) among whom 14 474 (10.50%) reported exposure for at least 10 years. Overall, exposure toLWH for ≥10 years was associated with an increased risk ofIHD , adjusted odds ratio (aOR) 1.24 (1.08–1.43),P =0.0021. In stratified analyses, this effect was not observed in women, but was significant amongst men, aOR 1.28 (1.11–1.48),P =0.0008.Conclusions This large population‐based study supports an association between cumulative exposure toLWH andIHD in men. Future research should consider relevant strategies for reducingLWH exposure and duration.