The cut-off value for diagnosing heart failure by age Diagnosing heart failure Age Optimal cut-off value (pg / ml) Confirmed diagnosis < 50 450 50 - 75 900 > 75 1800 Excluding at any ages < 300 The cut-off value was determined as the value that the NT-proBNP level had the maximal sensitivity and specificity, calculated by maximal J index (Youden Index).