Internal validation and clustering stability analyses were performed.<h4>Results</h4>ILD + /PAH + patients showed a higher systemic inflammatory burden, including higher ESR (38 [21-61.5] vs. 23 [10-45] mm/h, <i>p</i> = 0.008), hs-CRP (10.15 [3.34-28.18] vs. 5.9 [1.5-16.1] mg/L, <i>p</i> = 0.017), CRP/albumin ratio (0.33 [0.11-0.95] vs. 0.17 [0.04-0.49], <i>p</i> = 0.019), and SII (1124.76 [700.8-2034.14] vs. 820.34 [461.33-1197.08], <i>p</i> = 0.013) compared with ILD-/PAH-. The gene discussed is CRP; the disease is pulmonary arterial hypertension.