NPPB and pulmonary arterial hypertension: Both ICOS (AUC: 0.843, CI 95% 0.754–0.909; p < 0.0001) and ICOS-L (AUC: 0.815, CI 95% 0.724–0.887; p < 0.001) demonstrated a good diagnostic performance in detecting PAH among CTD patients, similar to those of well-consolidated biomarkers of PH, such as BNP and uric acid (AUC: 0.881, CI 95% 0.796–0.939 and AUC: 0.711, CI 95% 0.606–0.801; p = n.s. for all comparisons).