Shift work and cardiovascular disease

Abstract: Shift work is a work schedule being the opposite of normal daytime work, often defined as working time outside normal daytime hours (06:00 to 18:00). In recent years, shift work has been associated with an increased risk of numerous chronic conditions including for example cardiovascular disease, some types of cancer, type II diabetes, and the metabolic syndrome. While some studies on the association between shift work and chronic disease have found results supporting it, others have not. Therefore, more research is needed to clarify potential associations.The aim of this thesis was to further study the proposed association between shift work and cardiovascular disease. This was addressed by performing two studies, one analysing if shift workers had an increased risk of ischemic stroke compared to day workers. The other study analysed whether shift workers had an increased risk of short-term mortality (case fatality) after a myocardial infarction compared to day workers. The studies were performed using logistic regression analysis in two different case-control databasesThe findings from the first study indicated that shift workers did not have an increased risk of ischemic stroke. The findings from the second study showed that male shift workers had an increased risk of death within 28 days after a myocardial infarction; the results did not indicate an increased risk for female shift workers. The results from both studies were adjusted for both behavioural and medical risk factors without affecting the results. The findings from this thesis provide new evidence showing that male shift workers have an increased risk of death 28 days after a myocardial infarction, however more research is needed to clarify and characterise any such potential associations.