The diagnostic accuracy and utility of a B-type natriuretic peptide test in a community population of patients with suspected heart failure.
BACKGROUND
National guidelines suggest the use of natriuretic peptides in suspected heart failure but there have been no studies comparing assays in primary care.


OBJECTIVE
To test and compare the diagnostic accuracy and utility of B-type natriuretic peptide (BNP) and N-terminal B-type natriuretic peptide (NT proBNP) in diagnosing heart failure due to left ventricular systolic dysfunction in patients with suspected heart failure referred by GPs to one-stop diagnostic clinics.


METHODS
Community cohort, prospective, diagnostic accuracy study.


METHODS
One-stop diagnostic clinics in Darlington Memorial and Bishop Auckland General Hospitals and general practices in South Durham.


METHODS
Two hundred and ninety-seven consecutive patients with symptoms and signs suggestive of heart failure referred from general practice.


METHODS
The study measured sensitivity, specificity, positive and negative predictive values (PPV, NPV), and area under receiver operating characteristic curve for BNP (near patient assay) and NT proBNP (laboratory assay) in diagnosis of heart failure due to left ventricular systolic dysfunction. The NPV of both assays was determined as a potential method of reducing the number of referrals for echocardiography.


RESULTS
One hundred and fourteen of the 297 patients had left ventricular systolic dysfunction (38%). At the manufacturer's recommended cut-off of 100 pg/ml BNP gave a NPV of 82%. BNP performed better at a cut-off of 40 pg/ml with a NPV of 88%. At a cut-off of 150 pg/ml, NT proBNP gave a NPV of 92%. Using cut-offs of 40 pg/ml and 150 pg/ml for BNP and NT pro-BNP, respectively, could have prevented 24% and 25% of referrals to the clinic, respectively.


CONCLUSIONS
In this setting, NT pro-BNP performed marginally better than BNP, and would be easier to use practically in primary care. A satisfactory cut-off has been identified, which needs validating in general practice. NT pro-BNP could be used to select referrals to a heart failure clinic or for echocardiography. This process needs testing in real-life general practice.
Fuat
Ahmet
A
Department of Medicine, Darlington Memorial Hospital, Centre for Integrated Health Care Research, University of Durham, Darlington Primary Care Trust. ahmet@fuat.freeserve.co.uk
Murphy
Jeremy J
JJ
Hungin
A Pali S
AP
Curry
Jane
J
Mehrzad
Ali A
AA
Hetherington
Andrew
A
Johnston
Jennifer I
JI
Smellie
W Stuart A
WS
Duffy
Victoria
V
Cawley
Patricia
P
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D015331:Cohort Studies; D004452:Echocardiography; D005194:Family Practice; D005260:Female; D006333:Heart Failure / Q000175:diagnosis* / Q000209:etiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D020097:Natriuretic Peptide, Brain / Q000097:blood*; D010446:Peptide Fragments / Q000097:blood*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012017:Referral and Consultation; D012680:Sensitivity and Specificity; D018487:Ventricular Dysfunction, Left / Q000150:complications / Q000175:diagnosis*
D015415:Biomarkers; D010446:Peptide Fragments; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain