The use of dual-energy X-ray absorptiometry in the evaluation of obesity in women with obstructive sleep apnea-hypopnea syndrome.

The inflammatory state caused by obesity increases the level of adipokines, such as leptin, with a direct impact on the central respiratory regulation. The present study addresses this problem by evaluation of the association of sleep apnea diagnosis in relation to body fat measured by dual-energy X-ray absorptiometry (DXA), anthropometric parameters and biochemical variables. All patients carried out overnight polysomnography, anthropometric evaluations [Body Mass Index (BMI), neck and waist circumference], body composition analyzed by DXA and blood sample collection (lipid profile, fasting glycemia, insulin, glycated hemoglobin, C-reactive protein and serum leptin levels). Obstructive sleep apnea-hypopnea syndrome (OSAHS) was defined by the apnea-hypopnea index (AHI) from the overnight polysomnography. According to the AHI, the women were divided into two groups: with and without apnea. Twenty-seven of them had OSAHS (AHI = 22.04 ± 17.55). The main results are the following: (a) BMI was not capable of predicting OSAHS in this study (p = 0.204); (b) for each 1 % increase in TBF %, the probability of having sleep apnea increased by 12.8 %; (c) comparing all variables (anthropometrics, DXA and blood sample), serum leptin was the only variable with a significant difference between the groups (p = 0.0257). The results reinforce the role of total body fat and leptin in the etiology of OSAHS and the need to include the evaluation of corporal composition measures by DXA in studies of sleep apnea.