What criteria were used to determine the scope of the review protocol?
The review protocol was limited to studies of patients presenting in a primary care or outpatient setting, excluding studies of patients in an acute setting or immediately post myocardial infarction (MI). The 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. Furthermore, the review was only to include studies using a reference standard of echocardiography plus clinical assessment for the diagnosis of heart failure, excluding studies using echocardiography alone or reduced ejection fraction on echocardiography as a reference standard.