Xin Xue,1 Zhe Zhao,2 Li-Bo Zhao,2 Ying-Hui Gao,3 Wei-Hao Xu,4 Wei-Meng Cai,5 Shao-Hua Chen,5 Tian-Jiao Li,6 Ting-Yu Nie,6 Dong Rui,5 Yao Ma,5 Xiao-Shun Qian,1 Jun-Ling Lin,7 Lin Liu1 

1Department of Pulmonary and Critical Care Medicine of the Second Medical Center, Chinese PLA General Hospital, Beijing, People’s Republic of China; 2Department of Vasculocardiology, Second Medical Center of Chinese PLA General Hospital, Beijing, People’s Republic of China; 3PKU-Upenn Sleep Center, Peking University International Hospital, Beijing, People’s Republic of China; 4Department of Geriatrics, Guangdong Provincial Geriatrics Institute, Guangdong Provincial People’s Hospital, Guangdong Academy of Medical Sciences, Southern Medical University, Guangzhou, People’s Republic of China; 5Department of Pulmonary and Critical Care Medicine, Second Medical Center of Chinese PLA General Hospital, Beijing, People’s Republic of China; 6Medical College, Yan’ an University, Yan’ an, People’s Republic of China; 7Department of Respiratory and Critical Care Medicine, Beijing Chaoyang Hospital Affiliated to Capital Medical University, Beijing, People’s Republic of China

Correspondence: Lin Liu, Department of Pulmonary and Critical Care Medicine of the Second Medical Center, Chinese PLA General Hospital, Beijing, People’s Republic of China, Email liulin715@qq.com Jun-Ling Lin, Department of Respiratory and Critical Care Medicine, Beijing Chaoyang Hospital Affiliated to Capital Medical University, Beijing, 100020, People’s Republic of China, Email 18611521849@163.com

Background: Previous studies have demonstrated a significant correlation between obstructive sleep apnea (OSA) and frailty. However, the association of mean pulse oxygen saturation (MSpO2) with frailty among OSA patients remains unconfirmed. This study aimed to explore this potential association using data from a multicenter, prospective cohort.
Methods: A total of 1006 elderly patients diagnosed with OSA through polysomnography (PSG) from January 2015 to October 2017 were enrolled. Patients were stratified into four groups according to their MSpO2 levels to assess differences in frailty onset. Multivariate Cox regression analysis, Kaplan-Meier curves, restricted cubic splines, and subgroup analyses were employed to evaluate variations in frailty onset across different MSpO2 levels.
Results: Over a median follow-up period of 52 months, 275 patients developed frailty. Analysis using restricted cubic splines revealed a U-shaped trend between MSpO2 and frailty risk (non-linear p-value = 0.028). Patients in the lowest quartile (MSpO2 <  91.6%) exhibited a higher risk of frailty (hazard ratio [HR] = 1.43, 95% confidence interval [CI] 1.03– 1.97, P = 0.029) compared to those in the third quartile (MSpO2 93– 95%). Subgroup and sensitivity analyses confirmed the robustness of the U-shaped relationship.
Conclusion: There is a U-shaped association between MSpO2 and frailty among patients with OSA. Enhancing MSpO2 levels may mitigate the risk of frailty and improve prognosis in this population.

Keywords: obstructive sleep apnea, frailty, mean pulse oxygen saturation, elderly