Professional Driver's Job Stress and 8-year Risk of Cardiovascular Disease: The Taiwan Bus Driver Cohort Study.

BACKGROUND: Two main job stress models-the Demand-Control-Support (DC) model and the Effort-Reward Imbalance (ERI) model have been used to assess the impact of psychosocial work-related factors for cardiovascular disease (CVD). Limited evidence elaborates the independent and combined effects on CVD events, especially for professional drivers. This study assesses the independent and combined effects of DC and ERI models on an 8-year risk of CVD among professional drivers. METHODS: The Taiwan Bus Driver Cohort Study recruited 1650 professional drivers from a large bus company in 2005. The subjects were interviewed in person and completed the two job stress questionnaires. Researchers found 94 new cases of CVD (International Classification of Diseases, Ninth Revision, Clinical Modification [ICD-9-CM]: 390-459) from 2006 to 2012. A Cox proportional hazards model was performed to estimate the hazard ratio (HR) for CVD events. RESULTS: Occupational drivers with high overcommitment scores (thresholds of 15) had an elevated risk for CVD (HR = 1.71; 95% CI = 1.04, 2.82). Regarding target disease, overcommitment had an increased risk for CVD (not including hypertensive disease) (HR = 1.27; 95% CI = 1.05, 1.54) and ischemic heart disease (HR = 1.32; 95% CI = 1.05-1.65). CONCLUSION: Overcommitment, which is associated with job stress, appears to be associated with CVD risk in professional drivers.

Usefulness of overnight pulse oximeter as the sleep assessment tool to assess the 6-year risk of road traffic collision: evidence from the Taiwan Bus Driver Cohort Study.

Background: In order to support health service organizations in arranging a system for prevention of road traffic collisions (RTC), it is important to study the usefulness of sleep assessment tools. A cohort study was used to evaluate the effectiveness of subjective and objective sleep assessment tools to assess for the 6-year risk of both first RTC event only and recurrent RTC events. Methods: The Taiwan Bus Driver Cohort Study (TBDCS) recruited 1650 professional drivers from a large bus company in Taiwan in 2005. The subjects were interviewed in person, completed the sleep assessment questionnaires and had an overnight pulse oximeter survey. Moreover, this cohort of drivers was linked to the National Traffic Accident Database (NTAD) and researchers found 139 new RTC events from 2005 to 2010. Primary outcomes were traffic collisions from NTAD, nocturnal oxygen desaturation index (ODI) from pulse oximeter, Pittsburg sleeping quality score, Epworth daytime sleepiness score, Snore Outcomes Survey score and working patterns from questionnaires. A Cox proportional hazards model and an extended Cox regression model for repeated events were performed to estimate the hazard ratio for RTC. Results: The RTC drivers had increased ODI4 levels (5.77 ± 4.72 vs 4.99 ± 6.68 events/h; P = 0.008) and ODI3 levels (8.68 ± 6.79 vs 7.42 ± 7.94 events/h; P = 0.007) in comparison with non-RTC drivers. These results were consistent regardless of whether ODI was evaluated as a continuous or a categorical variable. ODI4 and ODI3 levels increased the 6-year RTC risks among professional drivers even after adjusting for age, education, history of cardiovascular disease, caffeine intake, sleeping pills used, bus driving experience and shift modes. Moreover, there was an increased trend for ODI between the stratification of the number of RTCs in comparison with the non-RTC group. In the extended Cox regression models for repeated RTC events with the Anderson and Gill intensity model and Prentice-Williams-Petersen model, measurement of ODI increased hazards of the subsequent RTC events. Conclusion: This study showed that an increase in the 6-year risk of RTC was associated with objective measurement of ODI for a sign of sleep-disordered breathing (SDB), but was not associated with self-reported sleeping quality or daytime sleepiness. Therefore, the overnight pulse oximeter is an effective sleep assessment tool for assessing the risk of RTC. Further research should be conducted regarding measures to prevent against SDB among professional drivers.

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.

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 10events/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.

The Association between Obstructive Sleep Apnea and Metabolic Markers and Lipid Profiles.

PURPOSE: The purpose of this study was to investigate the association between apnea-hypopnea index (AHI) and metabolic markers and whether the elevated risk of Metabolic Syndrome (MetS) is related to Obstructive Sleep Apnea (OSA). METHODS: This cross-sectional study recruited 246 male bus drivers from one transportation company in Taiwan. Each participant was evaluated by a polysomnography (PSG) test and by blood lipids examination. Severity of OSA was categorized according to the apnea-hypopnea index (AHI). RESULTS: The results showed that a 73.3% prevalence of MetS in OSA (AHI > 15) and a 80.0% prevalence of MetS in severe OSA (AHI > 30) were found. After adjusting for confounding variables, an increased level of Body-Mass Index (BMI) and two non-MetS cardiovascular risk factors, total cholesterol/HDL-C ratio and TG/HDL-C ratio was significantly associated with AHI in subjects with severe OSA. MetS was about three times to be present in subjects with severe OSA, even adjusted for BMI. CONCLUSIONS: The findings showed a high prevalence of MetS in OSA among professional drivers, especially in the severe group category. BMI was the major contributing factor to OSA. However, the present study did not find a sensitive clinical marker of a detrimental metabolic profile in OSA patients.

The impact of obstructive sleep apnea on high-sensitivity C-reactive protein in subjects with or without metabolic syndrome.

BACKGROUND: It is unclear whether obstructive sleep apnea (OSA) is independently associated with increased levels of the acute-phase reactant C-reactive protein (CRP). The purpose of this study was to evaluate the relationship between OSA and high-sensitivity CRP (hs-CRP) levels according to the presence or absence of metabolic syndrome (MetS). METHODS: This study recruited 245 male bus drivers from one transportation company in Taiwan. Each participant was evaluated by a polysomnography (PSG) test, blood lipids examination, and hs-CRP. Severity of OSA was categorized according to the apnea-hypopnea index (AHI). RESULTS: Subjects were categorized into severe OSA group (n = 44; 17.9 %), moderate and mild OSA group (n = 117; 47.8 %), and non-OSA group (n = 84; 34.3 %). AHI had a significant association with hs-CRP (ß = 0.125, p = 0.009) adjusting for age, smoking, drinking, and MetS status. Hs-CRP was elevated with severe OSA (ß = 0.533, p = 0.005) even adjusting for BMI and MetS. Moreover, there was an independent effect for adjusted odds ratios (AORs) between the stratification of the severity for OSA and MetS. CONCLUSION: Elevated hs-CRP level is associated with severe OSA, independent of known confounders. The effect of OSA in CRP is independent of MetS was identified.

High job strain is associated with inflammatory markers of disease in young long-haul bus drivers.

Atherosclerosis is an inflammatory disease. The study was aimed to investigate the association between job strain and inflammation markers and to examine factors contributing to high strain. The long-haul bus drivers (n = 825) were recruited from a Taiwanese transportation company. The psychosocial work environment was measured by a validated job content questionnaire (JCQ). Plasma high sensitivity C-reactive protein (hs-CRP) and homocysteine (Hcy) were analyzed as inflammation markers. Job strain effects and its interaction with age were analyzed by logistic regression. Explained variance (Nagelkerke R square) was applied to select important stressors. The crude and adjusted odds ratio (OR) for the effect of high strain on high hs-CRP and Hcy were not significant. However, there was significant interaction between job strain and age (p = .014). The significantly increased risk of high strain on high hs-CRP was found among drivers younger than 35 years old (OR = 2.71), but not in driver groups age 35 to 49 and older than 50. The contributing factors to high strain were varied among the 3 age groups. The 3 stressors found for young drivers were having rest time less than 8 hours between 2 shifts, being physically inactive during leisure time, and frequent driving more than 12 hours a day. Job strain interacted with age influenced hs-CRP levels. The risk of inflammatory disease markers only increased in high strained group of young drivers. Appropriate work shift systems should be implemented to increase off-duty time, reduce sleep restrictions, and increase physical activity during leisure time.