Abstract: Objective To investigate the relationship between obstructive sleep apnea (OSA) and components of metabolic syndrome (MetS) in the elderly and the implications for long-term risk for major adverse cardiovascular events (MACE). Methods This multicenter prospective cohort study was conducted among 1157 consecutive patients with OSA [defined as an apnea-hypopnea index (AHI) ≥5 times/h recorded by overnight polysomnography] aged ≥60 years enrolled from January, 2015 to October, 2017. All the patients did not have a history of MACE at baseline and had complete documentations of MetS indicators. The baseline demographic data, clinical characteristics, biochemical markers, and sleep parameters were collected from all the patients, who were divided into 4 groups according to the quartile level of AHI and followed up for a median of 42 months for MACE and its component events (cardiovascular death, myocardial infarction, and hospitalization for unstable angina or heart failure). Multivariate linear regression and Cox proportional risk regression models were used to analyze the correlation of MetS components with major objective predictors of OSA, AHI and LSpO2 and the long- term risk of MACE. Results AHI and LSpO2 quartiles group showed a positive dose-response relationship with MetS components [fasting blood glucose, waist circumference, systolic blood pressure, and triglycerides] and a negative dose-response relationship with high-density lipoprotein level. MACE occurred in 119 (10.3% ) patients with OSA during the follow-up. Multivariate Cox regression analysis showed that a high triglycerides, a high systolic blood pressure, and an increased waist circumference were independent risk factors for MACE and its component events (P<0.05 or 0.01); a high HDL was a protective factor against MACE and myocardial infarction (P<0.05 or 0.01) independent of the AHI. MetS components independent of LSpO2 showed no significant correlations with the risk of MACE or its component events. Conclusion The major diagnostic indexes AHI and LSPO2 in elderly patients with OSA have a dose-response relationship with MetS components, and the interaction between the components of MetS and AHI can increase the risk of MACE and its component events.

Key words: obstructive sleep apnea; elderly; metabolic syndrome; major adverse cardiovascular events; cardiovascular diseases