Nocturnal Intermittent Hypoxia and the Risk of Cardiovascular Disease among Japanese Populations: The Circulatory Risk in Communities Study (CIRCS)

AIMS

Information is limited about the influence of obstructive sleep apnea (OSA) on developing cardiovascular disease (CVD) among Asian community-dwelling populations. We examined the association between nocturnal intermittent hypoxia as a surrogate marker of OSA and the risk of CVD in a Japanese community-based cohort study.

METHODS

We used baseline surveys from 2000 to 2008 to study the cohort data of 5,313 residents from three Japanese communities who were between the ages of 40 and 74 years and initially free from ischemic heart disease and stroke. We assessed the number of 3% oxygen desaturation index (ODI) as the indicator of nocturnal intermittent hypoxia. We divided individuals into two groups depending on 3% ODI (3% ODI ≥ 5 or 3% ODI ＜5). Cox proportional hazards regression models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for CVD according to 3% ODI. Age, sex, body mass index, alcohol, and smoking were adjusted in the multivariable models.

RESULTS

During 12.8 years of the median follow-up with 66,796 person-years, 185 cases with CVD (115 stroke and 70 coronary heart disease [CHD]) were recorded. The multivariable HRs (95% CIs) were 1.49 (1.09-2.03), 2.13 (1.08-4.22), and 1.93 (1.16-3.19) for the 3% ODI ≥ 5 group versus the 3% ODI ＜5 group of developing CVD, lacunar infarction, and CHD, respectively.

CONCLUSIONS

Nocturnal intermittent hypoxia may increase the risk of developing lacunar infarction and CHD among community-dwelling Japanese populations. However, we could not find a significant risk of developing total stroke or stroke subtypes such as intraparenchymal hemorrhage, subarachnoid hemorrhage, and total ischemic stroke.

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.