NPPB and chronic obstructive pulmonary disease: We found that among patients with COPD, (1) criteria for severe PH mostly were based on mPAP of ≥ 35 mm Hg and rarely on mPAP of 25 to 34 mm Hg in combination with cardiac index of < 2.0 L/min/m2; (2) a simple, noninvasive clinical assessment using sPAP by echocardiography, NT-proBNP level, and the PA to Ao diameter ratio by chest CT scan predicts severe PH with high sensitivity and specificity; and (3) prognosis is limited independently by both the severity of airflow limitation and the severity of PH and that these factors are approximately equipotent.