Beiyao Gao,1,* Siyuan Wang,1,* Li Zhao,2– 5,* Hongbin Liao,6 Shiwei Qumu,4,5,7 Peijian Wang,1 Ting Yang,4,5,7 Shan Jiang1 

1Department of Rehabilitation Medicine, China-Japan Friendship Hospital, Beijing, People’s Republic of China; 2Department of Lung Transplantation, China-Japan Friendship Hospital, Beijing, People’s Republic of China; 3National Center for Respiratory Medicine, China-Japan Friendship Hospital, Beijing, People’s Republic of China; 4National Clinical Research Center for Respiratory Diseases, Beijing, People’s Republic of China; 5Institute of Respiratory Medicine, Chinese Academy of Medical Sciences, Beijing, China; 6Department of Clinical Medicine, Peking University, Beijing, People’s Republic of China; 7Department of Pulmonary and Critical Care Medicine, China-Japan Friendship Hospital, Beijing, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Shan Jiang, Email landjiang@126.com Ting Yang, Email zryyyangting@163.com

Objective: To identify predictive factors for different exercise-induced desaturation (EID) severities and evaluate health-related quality of life six months later in chronic obstructive pulmonary disease (COPD) patients.
Methods: This retrospective study consecutively analyzed 116 COPD outpatients (male: 82.8% [96/116]; age: 63.48 ± 7.48 years; disease severity distribution: GOLD 1/2/3/4 = 55.8%/34.6%/7.7%/1.9%). Patients were categorized into three groups based on oxygen desaturation (SpO2) during the six-minute walk test (6MWT): non-EID (n = 52), mild-EID (n = 42), and severe-EID (n = 22). EID was classified as follows: Mild EID: SpO2 decrease ≥ 4% with nadir SpO2 ≥ 90%. Severe EID: SpO2 decrease ≥ 4% with nadir SpO2 ≤ 90%. Non EID: SpO2 decrease < 4% with nadir SpO2 ≥ 90%. A six-month follow-up was conducted via telephone to record adverse events and assess quality of life using the Chinese version of the EQ-5D questionnaire, which includes five dimensions: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression, along with the EQ-VAS scale.
Results: Significant differences were observed across the three groups in peripheral blood oxygen saturation (SpO2, %), peak expiratory flow (PEF, L/s), PEF (%), forced expiratory volume in the first second (FEV1, L), FEV1 (%), 6MWT distance (6MWD, m), Borg dyspnea, and Borg fatigue scores. The optimal cutoff values for predicting EID severity was 54.45% for FEV1% (AUC=0.716), 450.5 m for 6MWD (AUC = 0.761), and 94.5% for resting SpO2 (AUC = 0.737). Multivariate logistic regression analysis identified low FEV1%, reduced 6MWD, and low resting SpO2 as risk factors for severe EID (FEV1%: p = 0.002; 6MWD: p = 0.008; SpO2: p = 0.018. Severe EID patients had significantly lower EQ-5D index and EQ-VAS scores (EQ-5D index: p = 0.002; EQ-VAS: P = 0.005), particularly in mobility and usual activities dimensions (mobility: p = 0.001; usual activities: p = 0.038).
Conclusion: Low FEV1%, reduced 6MWD, and low resting SpO2 are key risk factors for severe EID, provide practical thresholds for clinical management of EID in COPD patients.

Keywords: chronic obstructive pulmonary disease, exercise-induced desaturation, health-related quality of life