Clinical, anthropometric and upper airway anatomic characteristics of obese patients with obstructive sleep apnea syndrome

Background: Obese subjects are at increased risk of developing obstructive sleep apnea syndrome (OSAS). However, the individual role of local (i.e., upper airway-related) and general (clinical and whole-body anthropometric) characteristics in determining OSAS in obese patients is still controversial. Objectives: To contrast the clinical, anthropometric and upper airway anatomical features of obese subjects presenting or not presenting with OSAS. Methods: Thirty-seven obese (BMI >= 30 kg/m(2)) males with OSAS and 14 age- and gender-matched obese controls underwent clinical and anthropometric (BMI, waist-to-hip ratio and neck circumference) evaluation. In a subgroup of subjects (18 and 11 subjects, respectively), magnetic resonance imaging (MRI) during wakefulness was used to study the upper airway anatomy. Results: OSAS patients showed significantly higher BMI, waist-to-hip ratio and neck circumference as compared to controls ( p < 0.05). They also referred to nonrepairing sleep, impaired attention, and previous car accidents more frequently ( p < 0.05). The transversal diameter of the airways (TDAW) at the retroglossal level by MRI was found to be an independent predictor of the presence and severity of OSAS ( p < 0.05). Parapharyngeal fat increase, however, was not related to OSAS. A TDAW > 12 mm was especially useful to rule out severe OSAS ( apnea-hypopnea index > 30, negative predictive value = 88.9%, likelihood ratio for a negative test result = 0.19). Conclusions: MRI of the upper airway can be used in association with clinical and anthropometric data to identify obese males at increased risk of OSAS. Copyright (c) 2006 S. Karger AG, Basel