Comparison of PFT among different groups (table 3):
Spirometry represents a useful investigation for both the severity and follow up of ILD. Generally, in ILD, pulmonary function abnormalities showed a restrictive pattern with decreased lung compliance as well as lung volumes. CTD only group showed a forced expiratory volume in 1 s (FEV1) (% predicted) 101 ± 7, forced vital capacity (FVC) (% predicted) 95 ± 7, the mildILD group showed a FEV1% 77 ± 10, FVC% 72 ± 7, and the severeILD group showed a FEV1% 55 ± 5, FVC% 49 ± 8.