Obstructive Sleep Apnea and Carotid-Artery Intima-Media Thickness

STUDY OBJECTIVES: We investigated whether the carotid-artery intimamedia thickness (IMT) measured by ultrasonography, which is regarded as an indicator of atherosclerosis, was associated with the severity of obstructive sleep apnea (OSA). DESIGN: Cross-sectional study. SETTING: A sleep laboratory in a general hospital in Japan. PATIENTS: A total of 167 patients referred to the sleep laboratory of our hospital for screening or treatment of OSA were investigated. They had no history of chronic obstructive pulmonary disease, cerebrovascular disease, or cardiovascular disease. INTERVENTIONS: NA. MEASUREMENTS AND RESULTS: Obstructive sleep apnea was diagnosed by polysomnography. Carotid-artery IMT was measured by ultrasonography, and known risk factors for atherosclerosis (age, obesity, hyperlipidemia, hypertension, diabetes mellitus, and insulin resistance) were also investigated. Multiple regression analysis was performed to assess the association between IMT and the severity of OSA, after adjusting for confounding factors. This analysis revealed that the apnea-hypopnea index, the duration of an oxygen saturation below 90%, and the mean nadir oxygen saturation were significantly associated with the IMT after adjustment for confounding factors that could promote atherosclerosis. Moreover, OSA-related hypoxemia was associated with the IMT independently of the apnea-hypopnea index. CONCLUSIONS: Our results demonstrated that the severity of OSA is independently related to atherosclerosis and that the severity of OSA-related hypoxemia is more important than the frequency of obstructive events.