The association between irregular working hours and cardiovascular diseases in a multi-ethnic population: the HELIUS study

Background: Irregular working hours are a risk factor for cardiovascular diseases (CVD). Aims: We studied ethnic disparities in the association between irregular working hours and CVD, as well as the mediating stress-related pathways. Methods: Logistic regression was used to study the cross-sectional association between (a history of) irregular working hours and prevalent CVD (self-reported myocardial infarction, dotter/bypass operation or stroke) in 18 284 participants (18–71years) in a population of Dutch, South-Asian Surinamese, African Surinamese, Ghanaian, Turkish and Moroccan origin from the HELIUS study. We considered three mediator models adjusting for behavioural, physiological and psychosocial stress. We tested for interaction between irregular working hours and ethnicity and stratified the analysis by ethnicity. Results: The prevalence of CVD was 18% (717 out of 4041) and 14% (1963 out of 14 243) in individuals with versus without irregular working hours. Working irregular hours was associated with prevalent CVD (OR 1.27, 95% CI 1.15–1.40) after adjusting for sociodemographic confounders. There was a significant interaction between ethnicity and irregular working hours on CVD. Strongest associations with prevalent CVD were found for South-Asian Surinamese (OR 1.47, 95% CI 1.18–1.82), African Surinamese (OR 1.29, 95% CI 1.06–1.57) and Moroccans (OR 1.43, 95% CI 1.11–1.84). There were considerable ethnic differences in the mediating stress-related pathways that associate irregular working hours with prevalent CVD. Conclusions: Working irregular hours is associated with an increased prevalence of CVD in a multi-ethnic population. We show ethnic disparities in the associations between irregular working hours and CVD, as well as in the stress-related pathways that mediate these associations.