Hong Kong Academy of Medicine. CC BY-NC-ND 4.0
Cardiovascular risk in bus drivers
Chloe KY Cheung1, Sunny SL Tsang1, Oliver Ho1, Nathan Lam1, Edmund CL Lam1, Carolyn Ng1, Frances Sun1, Brian Yu1, Natalie Kwan1, Gilberto KK Leung1,2, MB, BS, PhD
1 Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong
2 Department of Surgery, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong
Corresponding author: Prof Gilberto KK Leung (gilberto@hku.hk)
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Driver health is an important issue worldwide. Cardiovascular risk is well known to be higher in bus drivers than in the general population.1 2 3 4 5 Although much media attention has been drawn towards the recent increase in bus accidents in Hong Kong,6 7 8 few studies or measures have been carried out. The aim of this study was to examine available findings on cardiovascular risks among bus drivers and related policies on risk modification internationally and in Hong Kong.
Cardiovascular risk in bus drivers
Previous studies have documented cardiovascular risk in professional drivers. In Korea, a cross-sectional study on 443 male bus drivers compared their incidence of hypertension (53.3%) with two control groups (17.6% and 19.7%, respectively). The results showed that the odds ratio of developing a cardiovascular event in bus drivers was 2.18 to 2.58.9 Another study was conducted through questionnaires on a randomly selected cohort of 440 professional drivers in Sweden. It found a 1.13-times higher relative risk of developing cardiovascular outcomes like stroke, and the odds ratio of developing a cardiovascular event was 2.34.3 Before the implementation of the Labour Standards Act, studies conducted on 2297 Taiwanese bus drivers and skilled workers also showed higher incidence of hypertension in bus drivers (72.4%, 986/1361) than skilled workers (30.6%, 164/536).2 The overall findings indicate that bus drivers of different nationalities exhibit a higher cardiovascular risk.
Risk factors in bus drivers
There are three main mechanisms predisposing bus drivers to higher cardiovascular risk.9 An acute episode due to a busy road with excessive traffic and aggressive drivers, is the first major cause. This is exacerbated by poor working conditions—a combination of long working hours and insufficient breaks in between shifts. These occupational factors lead to obesity,10 high blood pressure,11 and poorly controlled cholesterol levels.12 Finally, job stress from being chronically overworked is also a contributing cause.13
Regulatory measures
Regulations aimed at reducing bus drivers’ cardiovascular risk are well established in Singapore, Taiwan, and South Korea. In Singapore, all transport operators must comply with the Employment Act, which limits drivers’ working hours to 12 hours per day (including overtime).14 The maximum penalty for violation of regulations is SGD 5000 and a custodial sentence of 12 months.15 Under Singapore’s ‘Healthier Workers, Happier Workers’ programme, free health talks and regular health screening are provided at bus terminals during shift changes.16 The Taiwanese Labour Standards Act sets the maximum working hours of bus drivers to 12 hours a day and uses digital tachograph for monitoring.17 In South Korea, non-compliant bus companies will be subjected to a fine or temporary suspension of service.9 18 The installation of digital tachographs to record information about driving time and rest periods of drivers also effectively monitors overwork.18
Workers’ compensation
Cardiovascular risk in bus drivers is one of the most compensable conditions internationally,18 but it is not recognised in Hong Kong. In Japan, workers can be compensated for overwork-related health problems, known colloquially as ‘karoshi’ (death by overwork). Similarly, in Korea, the Ministry of Employment and Labor outlined criteria for work-related diseases liable for compensation to include cerebral infarction, hypertensive encephalopathy, coronary heart disease, and haemorrhagic stroke associated with existing hypertension.18 In contrast, Hong Kong bus drivers are rarely compensated, if at all, in this regard. According to the Employees’ Compensation Ordinance, the Labour Department would consider whether there is a direct causal relationship between the disease and certain type of work, taking into account the availability of supportive scientific evidence.19 Cardiovascular events do not fall under the definition of occupational diseases as they can be due to other factors that have no direct relationship with work such as eating habits.
Situation in Hong Kong
Recently, we conducted a questionnaire survey on 255 bus drivers and 252 non–bus drivers in Hong Kong (Table 1). We included Chinese men aged 25 to 84 years; recruitment of bus drivers was done at bus terminals and non–bus drivers were approached at random outside the exits to train stations. The QRISK3 (cardiovascular risk algorithm version 3 calculator) was used to assess cardiovascular risk by quantifying the 10-year risk for myocardial infarction and stroke in adults. Established cardiovascular risk factors including hypertension, hyperlipidaemia, diabetes, and smoking, and newly identified cardiovascular risk factors were taken into account.20 Systolic blood pressure values were obtained either by the drivers’ self-reporting, or by an automatic sphygmomanometer on the spot. Other parameters were based on subjects’ own recall.

Table 1. Demographic of bus drivers and non–bus drivers
Our results (Table 2) showed that the relative risk of developing cardiovascular diseases in bus drivers (2.41) is higher than in non–bus drivers (1.84) after age adjustment. This was attributable to low exercise levels, poor job satisfaction, and long durations of working hours (Table 3). The odds of developing hypertension (>140/90 mm Hg) in bus drivers was 1.62-times higher than in non–bus drivers (Table 4). Physical inactivity and smoking were factors predisposing to hypertension. Only 7.9% of bus drivers did physical exercise for >1 hour per day, and 47.4% were smokers, compared with 20.2% of non–bus drivers (Table 1). The sedentary lifestyle of bus drivers in Hong Kong is consistent with previous studies that indicated bus drivers spend 83% of their time at work sitting.21

Table 2. Cardiovascular risk parameters for bus drivers and non–bus drivers stratified by age

Table 3. Pearson correlations (r2) between relative risk and other variables for bus drivers and non–bus drivers

Table 4. Odds ratio of cardiovascular event risk to bus driving
Recommendations for Hong Kong bus drivers
Bus driver health is crucial for ensuring the safety of drivers, passengers, and other road-users. According to the World Health Organization recommendations, 30 minutes of aerobic exercise 3 times per week is ideal; short of that, there are still added benefits in moving from the category of “no activity” to “some levels” of activity.22 Smoking cessation can be introduced in a stepwise fashion, from counselling sessions, nicotine replacement therapy, and varenicline use, to community interventions introduced by the government.23 Educational programmes may be implemented within communities of professional drivers in order to improve the general health of bus drivers.
Currently, Hong Kong bus operators need to adhere to the Transport Department’s Guidelines regarding maximum duty hours (12 hours), maximum driving hours (10 hours), and minimum rest time (40 minutes after 6 hours of driving).19 However, bus operators are only issued warning letters for non-compliance. Indeed, previous surveys have shown that 51% of Hong Kong franchised bus drivers worked ≥2 hours of overtime per day.24 Therefore, there is a need for the relevant authorities to take action to safeguard bus drivers against overwork and associated health hazards. To enhance road safety, the feasibility of implementing regulatory measures or installation of digital tachographs to monitor work hours and regular health screening programmes should be explored in Hong Kong.
There is a higher relative risk of developing cardiovascular diseases in bus drivers in Hong Kong although most exhibit few cardiovascular symptoms and belong to a younger age-group. The odds of having hypertension were significantly higher in bus drivers than in non–bus drivers. Stronger advocacy for better lifestyle habits among bus drivers is needed. Future studies should elucidate the causative relationship between bus driving and cardiovascular risk to complement existing policies on employee compensation.
Author contributions
All authors contributed to the concept of the study, acquisition and analysis of the data, drafting of the manuscript, and critical revision of the manuscript for important intellectual content. All authors had full access to the data, contributed to the study, approved the final version for publication, and take responsibility for its accuracy and integrity.
Conflicts of interest
All authors have disclosed no conflicts of interest.
We thank all the survey participants, without whose support this commentary would not have been possible.
This commentary received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
Ethics approval
This study was approved by the Institutional Review Board of the University of Hong Kong/Hospital Authority Hong Kong West Cluster (Ref UW 18-340). Informed consent from subjects was obtained verbally.
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