Supplementary Material for: Value of Cardiopulmonary Exercise Testing in the Prognosis Assessment of Chronic Obstructive Pulmonary Disease Patients: A Retrospective, Multicentre Cohort Study

<b><i>Introduction:</i></b> Chronic obstructive pulmonary disease (COPD) is one of the most common chronic diseases associated with high mortality. Previous studies suggested a prognostic role for peak oxygen uptake (VO₂peak) assessed during cardiopulmonary exercise testing (CPET) in patients with COPD. However, most of these studies had small sample sizes or short follow-up periods, and despite their relevance, CPET parameters are not included in the Global Initiative for Chronic Obstructive Lung Disease (GOLD) tool for assessment of severity. <b><i>Objectives:</i></b> We therefore aimed to assess the prognostic value of CPET parameters in a large cohort of outpatients with COPD. <b><i>Methods:</i></b> In this retrospective, multicentre cohort study, medical records of patients with COPD who underwent CPET during 2004–2017 were reviewed and demographics, smoking habits, GOLD grade and category, exacerbation frequency, dyspnoea score, lung function measurements, and CPET parameters were documented. Relationships with survival were evaluated using Kaplan-Meier analysis, Cox regression, and receiver operating characteristic (ROC) curves. <b><i>Results:</i></b> Of a total of 347 patients, 312 patients were included. Five-year and 10-year survival probability was 75% and 57%, respectively. VO₂peak significantly predicted survival (hazard ratio: 0.886 [95% confidence interval: 0.830; 0.946]). The optimal VO₂peak threshold for discrimination of 5-year survival was 14.6 mL/kg/min (area under ROC curve: 0.713). Five-year survival in patients with VO₂peak &lt;14.6 mL/kg/min versus ≥ 14.6 mL/kg/min was 60% versus 86% in GOLD categories A/B and 64% versus 90% in GOLD categories C/D. <b><i>Conclusions:</i></b> We confirm that VO₂peak is a highly significant predictor of survival in COPD patients and recommend the incorporation of VO₂peak into the assessment of COPD severity.

**引言**：慢性阻塞性肺疾病（Chronic obstructive pulmonary disease, COPD）是最常见的高致死性慢性疾病之一。既往研究显示，对慢性阻塞性肺疾病患者行心肺运动试验（cardiopulmonary exercise testing, CPET）时测得的峰值摄氧量（peak oxygen uptake, VO₂peak）具有预后价值。然而，此类研究大多样本量偏小或随访周期较短；尽管心肺运动试验参数具备临床相关性，但全球慢性阻塞性肺疾病防治创议（Global Initiative for Chronic Obstructive Lung Disease, GOLD）的病情严重程度评估工具尚未纳入此类参数。

**研究目的**：本研究旨在评估心肺运动试验参数在大型慢性阻塞性肺疾病门诊患者队列中的预后价值。

**研究方法**：本研究为回顾性多中心队列研究，对2004年至2017年间接受心肺运动试验的慢性阻塞性肺疾病患者的病历进行回顾性分析，记录患者的人口学特征、吸烟习惯、GOLD分级与分组、急性加重频率、呼吸困难评分、肺功能检测结果及心肺运动试验参数。采用Kaplan-Meier分析、Cox回归模型及受试者工作特征（receiver operating characteristic, ROC）曲线评估上述指标与患者生存率的相关性。

**研究结果**：本研究共纳入347例患者中的312例。患者的5年及10年生存率分别为75%与57%。峰值摄氧量可显著预测患者生存率（风险比：0.886，95%置信区间：0.830~0.946）。区分5年生存率的最佳峰值摄氧量阈值为14.6 mL/kg/min，受试者工作特征曲线下面积为0.713。在GOLD A/B组患者中，峰值摄氧量＜14.6 mL/kg/min者与≥14.6 mL/kg/min者的5年生存率分别为60%与86%；在GOLD C/D组患者中，两者的5年生存率分别为64%与90%。

**研究结论**：本研究证实，峰值摄氧量是慢性阻塞性肺疾病患者生存率的显著预测因子，建议将峰值摄氧量纳入慢性阻塞性肺疾病的病情严重程度评估体系。