Detection, Severity, and follow up of chILD
Pulmonary function test (PFT): Patients underwent the PFT using spirometry. The following parameters were recorded: forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), FEV1/FVC ratio. These parameters were all expressed as a percentage of measured value/predicted value. Interpretation of PFT according to Jiang, Tao, Zuo, Li, Wang, Fang, Xu, Li 20, pulmonary function value FVC, FEV1>80% of predicted values was considered as normal, Patients were considered as having mild ILD if they had (60%<FVC, FEV1<80% of predicted values) in PFT, and Patients were considered as having severe ILD if they had (FVC, FEV1<60% of predicted values) in PFT.