In 2017, Hoeper et al. (20) reported the COMPERA (Comparative, Prospective Registry of Newly Initiated Therapies for Pulmonary Hypertension) model which uses six variables: WHO-FC, 6MWD, NT-proBNP (or BNP), mRAP, CI, and mixed venous oxygen saturation (SvO2). Here, NPPB is linked to pulmonary arterial hypertension.