Long working hours associated with increased stroke risk
Long working hours are associated with an increased risk of stroke, particularly among those exposed to long working hours for 10 years or more and in young people, according to the results of a large general population study.
In the final sample of 143,592 participants, 42,542 (29.6 percent) reported long work hours (defined as working time of over 10 hours daily for at least 50 days per year), 14 481 (10.1 percent) reported exposure to long working hours for 10 years or more, and a total of 1,224 strokes were recorded. Long working hours were associated with a 29 percent increase in the risk of stroke (adjusted odds ratio [OR], 1.29; 95 percent confidence interval [CI], 1.11 to 1.49). [Stroke 2019;50:1879-1882]
“The adjusted OR for persons exposed to 10 or more years of long working hours was 1.45 [95 percent CI, 1.21 to 1.74],” the investigators reported.
“Younger people had a higher risk of stroke when exposed to long working hours for more than 10 years,” they noted. In participants under 50 years of age who had been exposed to 10 or more years of long working hours, the adjusted OR for stroke was 2.28 (95 percent CI, 1.46 to 3.58).
In the population-based study, investigators retrieved information on age, sex, smoking, occupation, and working hours at baseline, using CONSTANCES (Cohorte des Consultants des Centres d'Examens de Santé), a French population-based cohort of randomly selected adults aged 18–69 years. CONSTANCES was started in 2012 and compiles data from self-administered questionnaires and health examination at affiliated health-screening centres.
Stroke was defined by a doctor who examined each study participant, following protocol guidelines to improve diagnosis accuracy. “Positive predictive values for self-reported stroke were around 60 percent in a UK study,” the investigators noted. [PLoS One. 2015; 10:e0137538. doi: 10.1371/journal.pone.0137538] “Though the clinician cannot check medical/imaging records, misclassification probably had a low impact on the association found. In this same cohort, diabetes mellitus recorded from the same examination protocol had high agreement with health claims data,” they explained.
Individuals with less than 6 months’ work experience, those with a history of predominately part-time jobs, as well as those who reported a stroke before the onset of exposure to long working hours were excluded from the study.
While no differences in the association of long working hours with stroke were found between men and women, stratification by occupation revealed a lesser effect of long working hours on the incidence of stroke for owners, managers, chief executive officers, professionals, and farmers. The investigators proposed that individuals in these occupations generally have greater decision latitude than other workers, thus accounting for a weaker association between long working hours and stroke.
According to the investigators, the study reveals a significant association between exposure to long working hours for a period of 10 years or more and history of stroke. “Our results support the temporal sequence and a dose-response relationship [between stroke and long working hours] exposure duration,” they stated.