Why We Use BNP Plus Clinical Judgment

On the Shoulders of Giants

Breathing Not Properly
Catchy name!  They found that clinical judgment for CHF in the ED was not that great.  We could tell who really had the disease, but markedly overcalled it.  Sensitivity was only 49% but specificity was 96%.  BNP had better overall diagnostic performance, with sensitivity 90%, specificity 74%.  Adding BNP to clinical judgment improved overall diagnostic accuracy (100*true positive + true negative) from 74% to 81.5%, with a combined sensitivity of 94%, specificity 70%.  So what's the moral of this story?  It may be difficult to tell which patients have heart failure on clinical grounds alone.

Spoon Feed
Acutely dyspneic patients in the ED can be more accurately diagnosed by adding BNP to clinical judgment.  BMJ did a nice EBM summary.  EM Nerd brings us up to today with a current look at recent meta-analysis of several BNP papers.


Abstract

Circulation. 2002 Jul 23;106(4):416-22.

B-type natriuretic peptide and clinical judgment in emergency diagnosis of heart failure: analysis from Breathing Not Properly (BNP) Multinational Study.

McCullough PA1, Nowak RM, McCord J, Hollander JE, Herrmann HC, Steg PG, Duc P, Westheim A, Omland T, Knudsen CW, Storrow AB, Abraham WT, Lamba S, Wu AH, Perez A, Clopton P, Krishnaswamy P, Kazanegra R, Maisel AS.

Author information:

1University of California, Veteran's Affairs Medical Center, San Diego, USA. mcculloughp@umkc.edu

Abstract

BACKGROUND:

We sought to determine the degree to which B-type natriuretic peptide (BNP) adds to clinical judgment in the diagnosis of congestive heart failure (CHF).

METHODS AND RESULTS:

The Breathing Not Properly Multinational Study was a prospective diagnostic test evaluation study conducted in 7 centers. Of 1586 participants who presented with acute dyspnea, 1538 (97%) had clinical certainty of CHF determined by the attending physician in the emergency department. Participants underwent routine care and had BNP measured in a blinded fashion. The reference standard for CHF was adjudicated by 2 independent cardiologists, also blinded to BNP results. The final diagnosis was CHF in 722 (47%) participants. At an 80% cutoff level of certainty of CHF, clinical judgment had a sensitivity of 49% and specificity of 96%. At 100 pg/mL, BNP had a sensitivity of 90% and specificity of 73%. In determining the correct diagnosis (CHF versus no CHF), adding BNP to clinical judgment would have enhanced diagnostic accuracy from 74% to 81%. In those participants with an intermediate (21% to 79%) probability of CHF, BNP at a cutoff of 100 pg/mL correctly classified 74% of the cases. The areas under the receiver operating characteristic curve were 0.86 (95% CI 0.84 to 0.88), 0.90 (95% CI 0.88 to 0.91), and 0.93 (95% CI 0.92 to 0.94) for clinical judgment, for BNP at a cutoff of 100 pg/mL, and for the 2 in combination, respectively (P<0.0001 for all pairwise comparisons).

CONCLUSIONS:

The evaluation of acute dyspnea would be improved with the addition of BNP testing to clinical judgment in the emergency department.

PMID: 12135939 [PubMed - indexed for MEDLINE]