Abstract
STUDY OBJECTIVES: Clinical studies have investigated whether obstructive sleep apnea (OSA) can modulate bone metabolism but data are conflicting. Bone mineral density (BMD) measured by dual-energy x-ray absorptiometry is the standard technique for quantifying bone strength but has limitations in overweight patients (body mass index [BMI] ≥ 25 kg/m(2)). The aim of this study was to examine the association between OSA and BMD by examining CT images that allow true volumetric measurements of the bone regardless of BMI. METHODS: Lumbar vertebrae BMD was evaluated in 234 persons (180 males and 54 females) by CT scan. The method was calibrated by a phantom containing a known concentration of hydroxyapatite. RESULTS: BMD was lower in male patients with severe OSA (apnea-hypopnea index [AHI] ≥ 30/h) than non OSA (AHI < 5; p < 0.05), while OSA and BMD had no association in females. Linear and multiple regression analyses revealed that age (p < 0.0001, β = -0.52), hypertension (p = 0.0068, β = -0.17), and the alveolar-arterial oxygen pressure difference (A-aDO2) (p = 0.012, β = -0.15) in males were associated with BMD, while only age (p < 0.0001, β = -0.68) was associated with BMD in females. CONCLUSION: Males with severe OSA had a significantly lower BMD than non OSA participants. Age, hypertension, and elevation of A-aDO2 were significant factors for BMD by CT imaging. The usefulness of measuring BMD in OSA patients by CT scanning should be studied in future.