Obstructive sleep apnea and the metabolic syndrome in an elderly healthy population: the SYNAPSE cohort.

BACKGROUND: Obstructive sleep apnea syndrome (OSA) has been recently considered as a cause and a component of the metabolic syndrome (MetS), previous studies showing the presence of OSA in about half of middle-aged patients having MetS. To date, no study has considered the association of OSA and MetS in the elderly. In this study we examine the prevalence of MetS and its strength association among healthy elderly OSA subjects. METHODS: A cohort of 806 subjects aged 68.5 years, participants of a 7-year follow-up study, was examined. All subjects underwent clinical evaluation, blood sample measurements, and an at-home polygraphy. OSA was assessed as an apnea/hypopnea index (AHI) >15, and MetS was diagnosed according to the Adult Treatment Panel III. RESULTS: In the total group, 9.8% of cases met criteria for MetS with a prevalence similar in men and women. Of the entire group with Mets, 51.3% were women and 48.7% men. OSA was diagnosed in 55.9% of the sample, and among the OSA group, 12.5% had MetS. Oxyhemoglobin desaturation index (ODI, p < 0.0001) and AHI (p = 0.003) were found significantly higher in subjects with MetS than in those without it. Most of MetS components were significantly associated with AHI and ODI, the relationship stronger with ODI. After adjustment for covariables such as obesity, gender, and presence of diabetes, ODI was independently associated with three MetS components, glycemia (p < 0.0001), hypertension (p = 0.002), and triglyceride levels (p = 0.02). Sleepiness, autonomic arousal index, and sleep duration had no effect on the metabolic parameters. CONCLUSIONS: In elderly subjects, the association between OSA and MetS was stronger for hyperglycemia and hypertension. Among factors explaining this association, hypoxemia appears to be the most important factor without any effect of indices of sleep fragmentation, sleep duration, and sleepiness.

Increased waist circumference is the component of metabolic syndrome the most strongly associated with elevated C-reactive protein in elderly.

BACKGROUND: Metabolic syndrome is associated with higher C-reactive protein (CRP) serum levels, a common biological marker of inflammation. However, the respective contribution of each component of metabolic syndrome to the inflammation has not been established. The aim of the present study was to assess the strength of the association between metabolic syndrome components and CRP in elderly subjects. METHODS: This was an observational, cross-sectional study on 921 volunteers (65.6 ± 0.8 years old) from the PROOF (PROgnostic indicator OF cardiovascular and cerebrovascular events) Study. Anthropometric, biological, and clinical parameters were evaluated. Subjects with a CRP value less than 10 mg/L were considered. The relationships between the metabolic syndrome components and CRP tertiles were evaluated using logistic regression analysis. RESULTS: After adjustment for gender and for body mass index, metabolic syndrome and high-CRP tertile were significantly associated [odds ratio (OR)=2.37, 95% confidence interval (CI) 1.46-3.87, P<0.001]. Waist circumference demonstrated the strongest association with the high-CRP tertile (OR=1.75, 95% CI 1.05-2.91, P<0.05). In addition, CRP levels significantly increased with the number of metabolic syndrome components. CONCLUSIONS: Among metabolic syndrome components, waist circumference showed the strongest association with the high-CRP tertile in elderly subjects. These findings help to explain the strong association between waist circumference and cardiovascular morbidity.