CRP and interstitial lung disease: Patients with CTD-ILD had lower CRP (7.2 vs 16.1 mg/L, P = 0.038), NSE (6.9 vs 8.4 ng/ml, P = 0.043) and C4 levels (204.0 vs 241.9 mg/L, P = 0.03) than CTD patients without ILD (n = 69).