Elsevier

International Journal of Cardiology

Volume 225, 15 December 2016, Pages 206-212
International Journal of Cardiology

Utility of overnight pulse oximeter as a screening tool for sleep apnea to assess the 8-year risk of cardiovascular disease: Data from a large-scale bus driver cohort study

https://doi.org/10.1016/j.ijcard.2016.09.110Get rights and content

Highlights

  • No systematically study has examined the effect of sleep-disordered breathing (SDB) on CVD in professional drivers.

  • The TBDCS recruited 1,014 professional drivers was used to assess the SDB and the 8-year CVD risk.

  • Nearly 40% and 70% elevated adjusted HR for CVD and hypertensive disease per 1-unit increase in ODI are found.

  • The overnight pulse oximeter is a useful sleep apnea research tool in large study populations for assessing the risk of CVD.

  • This evidence support health or labor service organizations that early screening and treatment of SDB to reduce CVD risk.

Abstract

Background

Professional drivers' work under conditions predisposes them for development of sleep-disordered breathing (SDB) and cardiovascular disease (CVD). However, the effect of SDB on CVD risk among professional drivers has never been investigated. A cohort study was used to evaluate the effectiveness of overnight pulse oximeter as a sleep apnea screening tool to assess the 8-year risk of CVD events.

Methods

The Taiwan Bus Driver Cohort Study (TBDCS) recruited 1014 professional drivers in Taiwan since 2005. The subjects completed questionnaire interview and overnight pulse oximeter survey. This cohort was linked to the National Health Insurance Research Dataset (NHIRD). Researchers found 192 CVD cases from 2005 to 2012. Cox proportional hazards model was performed to estimate the hazard ratio for CVD. The statistical analysis was performed using SAS software in 2015.

Results

ODI4 and ODI3 levels increased the 8-year CVD risk, even adjusting for CVD risk factors (HR: 1.36, 95% CI: 1.05 to 1.78; p = 0.022, and HR: 1.40, 95% CI: 1.03 to 1.90; p = 0.033). ODI4 and ODI3 thresholds of 6.5 and 10 events/h revealed differences of CVD risks (HR: 1.72, 95% CI: 1.00 to 2.95; p = 0.048, and HR: 1.76, 95% CI: 1.03 to 3.03; p = 0.041). Moreover, the ODI levels had an increased risk for hypertensive disease (not including essential hypertension).

Conclusions

This study concludes that ODI for a sign of SDB is an independent predictor of elevated risk of CVD. Further research should be conducted regarding measures to prevent against SDB in order to reduce CVD risk in professional drivers.

Introduction

Cardiovascular disease (CVD) is not only the number one cause of death worldwide, but it is also one of the compensable work-related diseases [1], [2]. Therefore, except for the common CVD risk factors including smoking, hypertension, diabetes, hyperlipidemia, obesity, physical inactivity or diet [1], [2], the work environment factors in professional drivers, such as irregular work shifts, long hours of driving, sedentary restricted postures, long-term sleep deficiency, noise and chemical exposures [3], [4], [5], [6], [7], [8], also have increased the probability of developing CVD [6], [9], [10], [11], [12].

Recently, sleep-disordered breathing (SDB) is increasingly being recognized as an important factor contributing to the burden of CVD [13], [14], [15], [16], [17], [18], [19]. SDB is a sleep disorder that involves cessation or a significant decrease in airflow in the presence of breathing effort, and causes recurrent oxyhemoglobin desaturations and arousals from sleep. SDB has been shown to be more common among professional drivers, which is likely because physical inactivity or unhealthy diet choices cause obesity, and irregular work schedules or long working hours cause circadian rhythm disruption and chronic sleep deficiency [3], [4], [20]. Previous studies identified that about 28.2% of professional drivers from the USA [21], 15.8% of professional drivers from Australia [20], and 10% of bus drivers from both the UK [22] and Hong Kong [23] suffered from sleep apnea, in contrast to 3%–7% prevalence of OSA within the general male population [24]. It is a significant labor health concern when one considers the relatively high and rising prevalence of SDB in this high-risk occupation.

Importantly, SDB is a treatable disease; therefore, studies on whether or not SDB contributes to or exacerbates CVD, could support a novel target for cardiovascular risk reduction in professional drivers. However, reviewing a previous study that related to the effect of SDB on CVD development in professional drivers has never been systematically investigated. Additionally, several problems were shown in this research field, including an incomplete CVD data collection, small sample sizes, and poor control for confounding factors, which limited the assessment of an independent pathogenic role for SDB, and did not show clear causal association. Thus, we performed a perspective cohort study to evaluate the effectiveness of overnight pulse oximeter as a sleep apnea screening tool to assess the 8-year risk of CVD events. We hypothesized that the oxygen desaturation index would predict CVD and CVD events such as hypertensive disease, ischemic heart disease (IHD), cerebrovascular disease, diseases of arteries, arterioles, and capillaries, and congestive heart failure (CHF), and that the associations would persist after adjusting for CVD risk factors.

Section snippets

Study population

The study procedure is presented in Fig. 1. The Taiwan Bus Driver Cohort Study (TBDCS) included 1650 professional drivers from the largest transportation companies in Taiwan. First, we used this cohort to link the Driving Hours Dataset (total number of records = 1,518,350 person-times) based on the Event Data Recorder from 2005 to 2007. We selected 1037 professional drivers whose total driving period exceeded 100 days during the 3 years after undergoing an assessment questionnaire interview and

Results

The descriptive statistics of the all drivers in terms of work patterns and demographic characteristics are presented in Table 1. Most of the cohort subjects were between 35 and 44 years old (42.7%), one-quarter of the cohort (27.9%) had more than 8 years of driving experience, and almost half of the subjects worked with irregular shifts in the baseline. About 50% of the cohort subjects were obese (BMI  30 kg/m2), 19% of subjects had a drinking habit (22.8%), and more than half of the subjects had

Discussion

This is the first large professional driver cohort study to show that nocturnal oxygen saturation is independently associated with future CVD events. The major finding of this study was that ODI levels are useful in the prediction of 8-year CVD risks, even adjusting for CVD risk factors. Furthermore, the ODI levels had an increase of HR for other CVD events such as cardiovascular disease (not including hypertensive disease), and hypertensive disease (not including essential hypertension).

Conclusion

In a large cohort of professional drivers, nocturnal oxygen saturation for a sign of SDB is an independent risk factor for increased future CVD events. The overnight pulse oximeter is a useful sleep apnea research tool in large study populations for assessing the risk of CVD. Further research should be conducted regarding measures to prevent against SDB in order to reduce future CVD risk among professional drivers.

The following are the supplementary data related to this article.

Funding sources

This study was partly supported by the National Health Research Institutes of Taiwan (98-EO-PP01, 99-EO-PP01, 00-EO-PP01, EO-101-PP-01, EO-102-PP-01 and EO-103-PP-01) and Institute of Occupational Safety and Health (IOSH96-M102 and IOSH97-M102), Taiwan.

Disclosures

None declared.

Conflicts of interest

None of the authors have any potential, perceived or real conflicts of interest.

Acknowledgments

The authors thank the administrators and drivers in the Bus Company for their participation and cooperation. The current analysis was based on data provided by the Health and Welfare Data Science Center, Ministry of Health and Welfare, Executive Yuan, Taiwan. The funder had no role in the study's design, data collection and analysis, decision to publish, or preparation of the manuscript.

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