Study designs of evaluations included in the review
Diagnostic accuracy studies were eligible for inclusion.
Specific interventions included in the review
Diagnostic studies of any type of B-type natriuretic peptide (BNP) assay were eligible for inclusion. The tests used in the included studies were ELISA, RIA and the ELISA N-terminal pro-BNP test.
Reference standard test against which the new test was compared
The studies had to compare a BNP test with echocardiography or radionuclide scans to determine ejection fraction, with or without additional clinical criteria, to be included in the review. The included studies used echocardiography alone (with a cut-off ranging from 30 to 50%) or in combination with clinical symptoms, or radionuclide scans alone (with a cut-off ranging from 35 to 40%), as the reference standard.
Participants included in the review
Studies of asymptomatic patients or patients with suspected acute CHF were eligible for inclusion. The prevalence of heart failure in the included studies varied: from 39 to 72% in patients with acute dyspnoea in tertiary care settings, with a similarly high prevalence in patients examined after a myocardial infarction and in patients with an existing diagnosis of CHF (with the exception of one study with low prevalence); from 10 to 30% among out-patients referred by general practitioners; and was less than 10% in screening studies of patients with risk factors for CHF and coronary heart disease.
Outcomes assessed in the review
Studies that presented sufficient data to allow the construction of a 2x2 contingency table were eligible for inclusion. The main outcome of interest was the negative likelihood ratio (LR) as the BNP test is mainly used to rule out CHF.
How were decisions on the relevance of primary studies made?
Two reviewers independently assessed studies for relevance. Any discrepancies were resolved by consensus.