Excessive work and risk of haemorrhagic stroke: A nationwide case-control study

Background: Adverse effect of excessive work on health has been suggested previously, but it was not documented in cerebrovascular diseases. Aim: The authors investigated whether excessive working conditions would associate with increased risk of haemorrhagic stroke. Methods: A nationwide matched case-control study database, which contains 940 cases of incident haemorrhagic stroke (498 intracerebral haemorrhages and 442 sub-arachnoid haemorrhages) with 1880 gender- and age- (±5-year) matched controls, was analysed. Work-related information based on the regular job situation, including type of occupation, regular working time, duration of strenuous activity during regular work and shift work, was gathered through face-to-face interviews. Conditional logistic regression analyses were used for the multivariable analyses. Results: Compared with white-collar workers, blue-collar workers had a higher risk for haemorrhagic stroke (odds ratio, 1·33 [95% confidence interval, 1·06-1·66]). Longer regular working time was associated with increased risk of haemorrhagic stroke [odds ratio, 1·38 (95% confidence interval, 1·05-1·81) for 8-12h/day; odds ratio, 1·95 (95% confidence interval, 1·33-2·86) for ≥13h/day; compared with ≤4h/day]. Exposure to ≥8h/week of strenuous activity also associated haemorrhagic stroke risk [odds ratio, 1·61 (95% confidence interval, 1·26-2·05); compared with no strenuous activity]. Shift work was not associated with haemorrhagic stroke (P=0·98). Positive associations between working condition indices and haemorrhagic stroke risk were consistent regardless of haemorrhagic stroke sub-types and current employment status. Conclusions: Blue-collar occupation, longer regular working time and extended duration of strenuous activity during work may relate to an increased risk of haemorrhagic stroke.