As shown in Figure 2, the receiver operating characteristic (ROC) analysis indicated an estimated area under the curve for NT-proBNP levels predicting severe/very severe stages of COPD of 0.88 (95% CI: 0.78–0.98, p = 0.001 < 0.05) and an optimal cut-off value based on the Youden index of 325 pg/mL, with a sensitivity (Se) of 52% and a specificity (Sp) of 88%. The gene discussed is NPPB; the disease is chronic obstructive pulmonary disease.