Phase angle is associated with neck circumference in sleep apnea patients--a cross-sectional study 

Abstract The aim of this study was to characterise the whole-body 50 kHz phase angle in patients with obstructive sleep apnoea (OSA) and to estimate it using other nutrition-related physical examination indices. We enrolled 117 patients with OSA who underwent polysomnography. Patients underwent body composition measurements, physical examinations, and nutrition-related laboratory tests, and were grouped according to neck circumference (NC) quartiles to analyse the correlation between NC and nutritional assessment index values. A significant positive correlation was observed between NC and various nutritional indicators, including height and whole-body 50 kHz phase angle. An increase in NC resulted in a corresponding increase in weight, body mass index, waist circumference, arm muscle circumference, whole-body 50 kHz phase angle, apnoea–hypopnea index, and the longest apnoea time. Further stepwise regression and multiple linear regression analyses revealed: whole-body 50 kHz phase angle =(0.126×waist circumference + 0.345×arm muscle circumference − 1.420- NC)/(-1.496). The whole-body 50 kHz phase angle in patients with OSA can be estimated using NC, arm muscle circumference, and waist circumference, helping assess the combined nutritional, inflammatory, and immune status of patients with OSA.