The most important factor is that the clinical review demonstrates that NT-proBNP has a greater sensitivity over a range of thresholds compared to BNP. The committee emphasised the clinical importance of sensitivity over specificity as the test is used as a rule out for heart failure. Secondly, on a practical level and since the test will be requested mainly by primary care and be sent to the laboratories with inherent delay in transport, NT-proBNP has a longer stability in blood samples than BNP (days versus 4-6 hours), therefore NT-proBNP is more appropriate for testing in primary care. Thirdly, although it is unlikely at this stage for a patient not diagnosed with heart failure to be on Sacubitril Valsartan which interferes with BNP physiology (TA388), natriuretic peptides can also be used for monitoring heart failure patients, therefore it would be more useful to have NT-proBNP as the baseline peptide in case monitoring was needed in a patient with heart failure who is subsequently treated with this new drug. The following NT-proBNP thresholds were chosen as comparators: 400pg/ml 2010 NICE recommended threshold and previous 2012 ESC threshold 125pg/ml 2016 ESC threshold 280pg/ml the optimal threshold found in one study included in clinical review359 , and also lies close to the middle of the other 2 thresholds. As a reference, a diagnostic strategy was also included where no NT-proBNP test is undertaken and all patients with suspected heart failure are referred for echocardiography plus specialist clinical assessment. The model is structured in 2 parts: A decision tree is used to calculate the proportion of the population that fall into one of a number of cohorts according to their underlying condition and test result. 