NPPA and interstitial lung disease: The external respiratory function parameters were as follows: (FVC (p = 0.044), FEV1 (p = 0.007), FVC/FEV1 (p = 0.003), MEF 25 (p = 0.004), MEF 50 (p = 0.007), MEF 75 (p = 0.068), endothelin-1 (p = 0.030), and MR-proANP (p = 0.030) were higher in patients with SS-ILD than in patients with COPD.