Supplementary Material for: The Value of Dyspnea and Spirometry in Detecting Relapse of Benign Tracheal Stenosis

Background: Benign tracheal stenosis may relapse after management. Objectives: This study aimed to assess the value of dyspnea and spirometry in detecting relapse of benign tracheal stenosis. Methods: Patients with benign tracheal stenosis were evaluated post-management, at regular follow-up and emergency visits, with the Medical Research Council (MRC) dyspnea scale, spirometry, and flexible bronchoscopy. Patient visits were categorized and compared, in terms of change in clinical and functional parameters, in 2 groups: visits with relapse (case group) and visits with no relapse (control group). The ability of the MRC dyspnea scale and spirometry to predict relapse was evaluated. Results: Thirty-five patients with benign tracheal stenosis were included. Mean follow-up duration was 3.2 years (standard deviation = 3.3). Spirometry data were analyzed from 43 relapse visits (23 patients) versus 90 nonrelapse visits. The MRC dyspnea score and most spirometric indices were associated with relapse. In the receiver operating characteristic analysis, forced expiratory volume in 1 s, forced expiratory flow when 25% of forced vital capacity has been expired, peak expiratory flow (PEF), and total peak flow were superior to the MRC dyspnea score in predicting relapse. Among spirometric indices, >10.8% of PEF reduction has been very sensitive and specific. Conclusions: This study supports the role of dyspnea and spirometry in monitoring benign tracheal stenosis, with spirometry predicting relapse even in clinically stable patients. PEF being a very sensitive index has the additional advantage of being assessed by peak flow meter and could potentially be used for remote monitoring.背景：良性气管狭窄经治疗后仍可复发。 研究目的：本研究旨在评估呼吸困难与肺量测定法（spirometry）在检测良性气管狭窄复发中的应用价值。 研究方法：对良性气管狭窄患者在治疗后、定期随访及急诊就诊时，采用医学研究委员会（Medical Research Council, MRC）呼吸困难量表、肺量测定法及可弯曲支气管镜（flexible bronchoscopy）进行评估。根据临床与功能参数的变化，将患者就诊分为复发组（病例组）与无复发组（对照组）并开展对比分析，同时评估MRC呼吸困难量表与肺量测定法预测复发的能力。 研究结果：本研究共纳入35例良性气管狭窄患者，平均随访时长为3.2年（标准差=3.3）。共分析43次复发就诊（23例患者）与90次无复发就诊的肺量测定数据。MRC呼吸困难评分与多数肺量测定指标均与复发存在显著关联。在受试者工作特征（Receiver Operating Characteristic, ROC）曲线分析中，第一秒用力呼气容积（forced expiratory volume in 1 s）、用力肺活量呼出25%时的用力呼气流量、峰流速（peak expiratory flow, PEF）及总峰流速在预测复发方面均优于MRC呼吸困难量表。在肺量测定指标中，峰流速降幅超过10.8%具有极高的敏感性与特异性。 研究结论：本研究证实呼吸困难与肺量测定法在良性气管狭窄监测中具有重要作用，且肺量测定法可在临床状态稳定的患者中预测复发。峰流速作为敏感性极高的指标，还具备通过峰流速仪进行检测的额外优势，有望用于远程监测。