The Impact of Age, Gender and Body Mass Index on the Polysomnography Variables

Abstract

Objective: This study aimed to analyse respiratory parameters in polysomnography, mean nocturnal pulse oxyhaemoglobin saturation (mean nocturnal SpO(2)), minimum SpO(2), total sleep time with <90% oxyhaemoglobin saturation (TST90), Oxygen Desaturation index (ODI), apnoea duration, Sleep Arousal index in obstructive sleep apnoea (OSA) and their relationship with Apnoea-hypopnea index (AHI), Body Mass index (BMI), age and gender. Materials and Methods: A total of 1.000 patients diagnosed with OSA using polysomnography between January 2018 and January 2019 were investigated retrospectively. All subjects underwent one night of laboratory-based polysomnography and were then classified in the polysomnography report as mild, moderate or severe OSA according to the AHI values. Results: A significant relationship between AHI and BMI, the male gender and age (p<0.01) was noted. A strong negative correlation between mean nocturnal SpO(2) and TST90 was also recorded. In all the oxymetric parameters, ODI was found to have a strong relationship with AHI. To distinguish between patients with and without apnoea, the mean nocturnal SpO(2) cut-off point was found to be 93.6%. Conclusion: A unit increase of BMI increases the OSA risk by 1.5 times and being male increases OSA risk by 7.6 times. Ageing is also associated with higher AHI. A mean nocturnal oxygen saturation of <93.6% is important in detecting apnoea in patients.