Electrocardiographic Changes and Work-related Stress – a Cross-sectional Study in a General Working Population

Abstract

Master thesis, Programme in Medicine, TITLE: Electrocardiographic Changes and Work-related Stress – a Cross-sectional Study in a General Working Population. Background: Work-related stress described by the job strain and effort-reward-imbalance models has been associated with increased cardiovascular risk. However, the evidence is not sufficient. Atrial fibrillation, LBBB (left bundle branch block), prolonged QTc and resting heart frequency are electrocardiographic markers of cardiovascular disease. If they could be linked to job strain and effort-reward imbalance it would add plausibility to an association between these models and an elevated cardiovascular risk. Aims: To explore the relationship between job strain and effort-reward imbalance and atrial fibrillation, LBBB, QTc and resting heart frequency demonstrated with resting ECG, with the general aim of giving a further basis for the evidence connecting work-related stress with an increased risk of cardiovascular disease. Methods: This cross-sectional survey investigated randomly selected men and women in Västra Götalandsregionen (n=1,552 and 1,094 in two different samples). Information about effort-reward imbalance, job strain and ECG parameters was collected during the period 2001-2004 as part of the INTERGENE/ADONIX research project. The regression models were adjusted for gender, age and current smoking. Results: No significant association was found between prolonged QTc and work-related stress. There were too few cases of atrial fibrillation and LBBB to allow for statistical analyses. In the adjusted model heart frequencies ≥90th percentile were significantly inversely related to job strain (OR 0.65, 95% CI 0.44-0.96). For heart frequencies ≤10th percentile there was an inverse but non-significant association (OR 0.73, 95% CI 0.49-1.09). Conclusions: No electrocardiographic parameters could be significantly, positively associated with job strain or effort-reward imbalance. The inverse relationships between job strain and high and low heart frequencies possibly indicate a reduced risk of cardiovascular disease. This finding is controversial, however, due to a lack of support from other studies and the limited ability of this study to ascertain causality. Key words: Work-related stress, job strain, effort-reward imbalance, ECG.