Relation of Central Fat Mass to Obstructive Sleep Apnea in the Elderly

Study Objectives: Obesity is a recognized risk factor for obstructive sleep apnea syndrome (OSAS). We evaluated whether total trunk and central fat mass (CFM) is associated with OSAS in elderly subjects. Design: Cross-sectional. Setting: Body composition assessment by dual-energy X-ray absorbsiometry (DEXA). Participants: 749 volunteers aged 67.2 +/- 0.8 years (59.4% women). Intervention: All participants underwent evaluation of their body composition by DEXA in parallel with clinical and polygraphic assessments. The presence of OSAS was defined by an apnea plus hypopnea index (AHI) >= 15. Measurements and Results: A total of 44.8% of the population had an AHI < 15, and 55.2% presented OSAS. OSAS subjects were more frequently overweight and had a higher total trunk fat mass and central fat mass (CFM). Correlation analyses revealed that body mass index (r = 0.27, P < 0.001), neck circumference (r = 0.35, P < 0.001), and CFM (r = 0.23, P < 0.001) were significantly related to AHI. Logistic regression analysis indicated that in mild OSAS cases (> 15AHI < 30), BMI (OR: 1.10; 95% CI: 1.03-1.18; P = 0.008), and male gender (OR: 1.49; 95% CI: 1.05-2.12, P = 0.03) were key factors explaining an AHI between 15 and 30. In severe cases (AHI > 30), male gender (OR: 3.65; 95% CI: 2.40-5.55; P < 0.001) and CFM (OR: 1.10; 95% CI: 1.03-1.19; P = 0.009) were significant independent predictors of OSAS. Clinical Trial Registration: NCT 00759304 and NCT 00766584. Conclusions: Although central fat mass plays a role in the occurrence of severe OSAS in men older than 65 years of age, its low discriminative sensitivity in mild OSAS cases does not warrant systematic use of DEXA for the diagnosis of OSAS.