11.04.diagnosis.bnp.chf by keralaguest


									                                                                                    CAT 11.09.04
                                                          Chris Wong, Genji Terasaki & EBM class
Clinically Appraised Topic
Evidence-Based Medicine (November 9, 2004)
Theme: Diagnosis

Clinical Bottom Line:
   1) Measurement of B-type natriuretic peptide in the setting of acute dyspnea is most
       useful for ruling out underlying CHF as a cause for dyspnea.
   2) The test is readily available at point of service. It costs less than
   3) Increasing values of B-type natriuretic peptide more strongly suggest underlying
       CHF as cause of dyspnea.

Question: In patients presenting with dyspnea of unknown etiology, what is the
sensitivity, specificity, and likelihood ratio of the BNP test in identifying heart failure as
a cause?

Search strategies:

Cochrane         “BNP”, “Natriuretic peptide”        No relevant articles.
Clinical         “BNP”                               No results.
Evidence         “Natriuretic”                       Several articles on the use of nesiritide
                                                     to prevent contrast-induced
                                                     nephropathy, none on heart failure.
TRIP             “BNP”                               4 evidence based articles, 1 non-
                                                     systematic review (Bandolier).
                                                     94 Diagnosis articles, of which 3 were
                                                     most relevant.
                                                     Note this search missed the NEJM
                                                     article from 2002 (but is found quickly
                                                     via related articles to McCullough et al
                                                     Circ 2002)
                 “BNP CHF”                           34 Diagnosis articles, a subset of the
                                                     search above.
PubMed           Clinical queries                    Same 94 as TRIP.
                 “ BNP” using diagnosis filter
                 "Natriuretic Peptide,               31 articles (too limited)
                 Brain/diagnostic use"[MeSH]
                 "Natriuretic Peptide,               2079 articles (too loose)
                 Brain"[MeSH]                        295 articles, 92 when limited to core
                 "Natriuretic Peptide,               clinical journals, of which several
                 Brain"[MeSH] AND "Heart             additional articles were found.
                 Failure,                            (Mueller et al NEJM 2004, 2002)
                                                                                 CAT 11.09.04
                                                       Chris Wong, Genji Terasaki & EBM class

1. Maisel AS, Krishnaswamy P, Nowak RM, McCord J, Hollander JE, Duc P, Omland T,
Storrow AB, Abraham WT, Wu AH, Clopton P, Steg PG, Westheim A, Knudsen CW,
Perez A, Kazanegra R, Herrmann HC, McCullough PA; Breathing Not Properly
Multinational Study Investigators. Rapid measurement of B-type natriuretic peptide in
the emergency diagnosis of heart failure. N Engl J Med. 2002 Jul 18;347(3):161-7.
2. Morrison LK, Harrison A, Krishnaswamy P, Kazanegra R, Clopton P, Maisel A.
Utility of a rapid B-natriuretic peptide assay in differentiating congestive heart failure
from lung disease in patients presenting with dyspnea. J Am Coll Cardiol. 2002 Jan
                                                                                                     CAT 11.09.04
                                                                           Chris Wong, Genji Terasaki & EBM class

The studies
1. Maisel et al. NEJM 2002.

                      Was there an independent, blind comparison               Yes, determined by two
                      with a reference standard?                               cardiologists based on
                                                                               clinical criteria/scoring
                                                                               systems and blinded to BNP
                                                                               and ED MD’s dx.
                      Was the diagnostic test evaluated in an                  Multicenter (including one

                      appropriate spectrum of patients (like those in          VA), international, 18 older
                      whom we would use it in practice?)                       with presenting symptoms
                                                                               of dyspnea. 56% male.
                      Was the reference standard applied regardless            Yes.
                      of the diagnostic test result?

                      Was the test validated in a second, independent          See Morrison subset done at
                      group of patients?                                       VA. Specificity consistently

                      What is the sensitivity?                          Cutoff 100 = 90% (88-92)
Clinical Importance

                      What is the specificity?                          Cutoff 100 = 76% (73-79)

                      Can you calculate a likelihood ratio, or          Cutoff 100 = LR+ - 3.75
                      is there one already calculated?                  Cutoff 100 = LR – 0.13
                                                                        See Table

                      In our practice, is the test               Test is available. Cost is $104.50 at
                      available? Affordable?                     UWMC Lab (does not factor in any
                      Accurate? Precise?                         negotiated discounts).

                      Can we generate a reasonable               Yes. Yes. Other supporting studies are
                      pre-test probability in our                available. Although the bulk of data
                      clinical scenario?                         comes from this study group.
                      Are the study patients similar to
                      our own?
                      Has anything changed since the
                      study was published?
                                                                             CAT 11.09.04
                                                   Chris Wong, Genji Terasaki & EBM class
    Will the resultant post-test          Yes.
    probabilities change our

                                                          Positive LR     Negative LR

                                                          2.55            0.05
                                                          3.58            0.09
                                                          3.75            0.13
                                                          4.14            0.16
                                                          5.00            0.18

A follow-up analysis:
   1. McCullough PA, 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. B-type natriuretic peptide and clinical judgment in emergency diagnosis of
       heart failure: analysis from Breathing Not Properly (BNP) Multinational Study.
       Circulation. 2002 Jul 23;106(4):416-22
This analysis showed that BNP performed better than Emergency Department physicians.
                                                                                 CAT 11.09.04
                                                       Chris Wong, Genji Terasaki & EBM class

An interesting randomized trial of the utility of adding BNP to diagnostic strategy based
on clinical outcomes – thus really a therapy article in essence.
2. Mueller C, Scholer A, Laule-Kilian K, Martina B, Schindler C, Buser P, Pfisterer M,
Perruchoud AP. Use of B-type natriuretic peptide in the evaluation and management of
dyspnea. N Engl J Med. 2004 Feb 12;350(7):647-54

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