This review protocol was limited to studies of patients presenting in a primary care or outpatient setting, on the basis that studies of patients in an acute setting now fall within the remit of the acute heart failure guideline. Studies in patients immediately post myocardial infarction (MI) were also excluded on the basis that they also more appropriately fall within the scope of the acute guideline. This review was also limited to patients presenting with signs or symptoms of heart failure, rather than the use of NT-proBNP to screen for heart failure in asymptomatic or high risk populations without signs or symptoms, as the aim of the review was to identify the most relevant evidence to the population of interest. In addition, this review protocol was limited to studies using a reference standard of echocardiography plus clinical assessment for the diagnosis of heart failure. The committee did not consider that echocardiography alone, or reduced ejection fraction on echocardiography, was an appropriate reference standard and studies using that reference standard were excluded from this review. The committee noted that patients can have reduced ejection fraction on echocardiography without having symptomatic heart failure, so echocardiography alone was not a sufficient reference standard. Further, patients with heart failure with preserved ejection fraction in particular could not be diagnosed with echocardiography alone as this diagnosis requires substantial clinical input and judgment. The committee also discussed the 2010 guideline recommendations that provide a different treatment pathway for patients with any previous MI (these patients were referred directly for echocardiography and specialist assessment, without prior natriuretic peptide testing). 