The NT-proBNP levels used in the present study to assess mild (41 cases), moderate (27 cases) and severe heart failure (12 cases), which were diagnosed according to the modified Ross criteria, were 1,184.31 (95% CI, 716.61–2,935.35), 3,353.57 (95% CI, 3,008.83–3,699.25) and 16,883.22 (95% CI, 5,718.77–5,000.32 ng/l), respectively. Here, NPPB is linked to heart failure.