Can long working hours damage your heart?

Grant Data
Project Title
Can long working hours damage your heart?
Principal Investigator
Dr Wong, Janet Yuen Ha   (Principal investigator)
Dr Chan Kelvin   (Co-Investigator)
Dr Fong Daniel Yee Tak   (Co-Investigator)
Start Date
Completion Date
Conference Title
Presentation Title
Long working hours, cardiovascular risks, heart rate variability, Chinese, socioeconomic status
Others - Medicine, Dentistry and Health
Block Grant Earmarked for Research (104)
HKU Project Code
Grant Type
Seed Fund for Basic Research
Funding Year
Cardiovascular disease (CVD) accounts for the bulk of annual non-communicable disease deaths worldwide, followed by cancers, respiratory diseases, and diabetes. There is also an increasing trend towards sudden death from CVD at a young age in developed countries. Key issues and problems: 1. Inadequate evidence on the risks of long working hours on cardiovascular diseases with adjustment for the socioeconomic status Although a meta-analysis reported the association between long working hours and cardiovascular risks (odds ratio, 1.37; 95% confidence interval, 1.11 to 1.70) among 11 studies [1], none of the studies accounted for socioeconomic status (SES). Obviously, SES (including considerations of education level, occupation, and household income) may affect cardiovascular risks via poverty, under nutrition, limited access to health care services and health inequalities [2, 3]. We hypothesized that the effect of long working hours on cardiovascular risks would remain after adjusting the SES as a confounding factor. 2. No consideration of biological measurement to assess cardiovascular risks in general population Although there have been validated risk prediction models for estimating the cardiovascular risks by using diabetes, cholesterolemia and traditional risk factors, for examples, Framingham Heart Study in US [4], QRISK2 in UK [5] and Wu et al’s predictive model for Chinese populations [6], there has been no consideration of direct biological measurement for predicting cardiovascular risks. In fact, there has been studies that showed heart rate variability (HRV) was a predictor for myocardial infraction [7]. Therefore, we proposed to include measurement of HRV to assess for its predictive power of cardiovascular risks by using the validated risk prediction scores for cardiovascular diseases. Apart from myocardial infraction, emerging studies also found reduced HRV in patients with stress [8], anxiety and depression [9]. As long working hours were found to affect mental health [10], we hypothesized that HRV would add to the prediction of cardiovascular diseases and act as a mediator on the path linking long working hours with cardiovascular risks. As HRV is a non-invasive measurement, the study results will have high significance and value to prevent or inform early treatment for cardiovascular diseases. Purpose of the proposed project: The aim of the study is to quantify the magnitude of the relationships between long working hours, socioeconomic status and cardiovascular risks by a general population-based household survey in 180 middle-aged Chinses adults. Its specific objectives are to: (1) determine the risk of long working hours on cardiovascular diseases with the adjustment of SES; (2) determine the prediction power of HRV on the cardiovascular risks; and (3) identify the mediating role of HRV on the pathway between long working hours and cardiovascular risks. The study will use the validated 10-year cardiovascular risk score from a point score model that has been calibrated in Chinese populations [6] (Attachment 2). Data collection will be conducted by self-administered questionnaires and health assessments comprising blood pressure, body weight and height, heart rate variability capillary blood glucose and total cholesterol level measurements by nurses.