Relationships between Nocturnal Intermittent Hypoxia, Arterial Stiffness and Cardiovascular Risk Factors in a Community-based Population: The Toon Health Study

Aim: Nocturnal intermittent hypoxia (NIH), a primary marker of obstructive sleep apnea, has increasingly been linked with cardiovascular morbidity and mortality. The purpose of this study was to investigate the association between NIH and arterial stiffness as measured according to the cardio-ankle vascular index (CAVI) based on cardiovascular risk factors in a Japanese community-dwelling population. Methods: We conducted a cross-sectional study in Toon city among 684 men and 1,241 women 30-79 years of age. The severity of NIH was defined as mild or moderate-to-severe according to five or 15 events/hour on the 3% oxygen desaturation index (ODI), respectively. Increased arterial stiffness was diagnosed according to a CAVI of >= 9. Results: The number of subjects with no, mild and moderate-to-severe NIH was 1,348 (70%), 451 (23%) and 126 (7%), respectively. Increased arterial stiffness was detected in 21.9% of the participants. The multivariable-adjusted odds ratio (95% CI) of severe NIH related to an increased CAVI in comparison with a 3% ODI of < 5 was 1.36 (0.82-2.23). The stratified logistic regression analysis showed that the multivariable-adjusted OR of severe NIH for an increased CAVI was remarkably increased in the individuals with a BMI of >= 25 (OR = 2.53, 1.08-5.96; p = 0.03). An interaction test showed a trend for an overweight status to be a modifier of the association between OSA and increased arterial stiffness (p = 0.05). Conclusions: NIH has a tendency to promote increased arterial stiffness as measured according to the CAVI, especially in overweight subjects.