NPPB and pulmonary arterial hypertension: The PAH group had significantly greater mean NT-proBNP levels compared with the at-risk group (1,817.6 ± 2,367.0 versus 277.6 ± 242.7 ng/ml; P < 0.0001), ILD group (133.0 ± 86.6 ng/ml; P < 0.0001 versus Group 1), and the control group (72.1 ± 37.8 ng/ml; P < 0.0001 versus Group 1).