How obesity affects the cut-points for B-type natriuretic peptide in the diagnosis of acute heart failure. Results from the Breathing Not Properly Multinational Study.
BACKGROUND
B-type natriuretic peptide (BNP) is valuable in diagnosing heart failure (HF), but its utility in obese patients is unknown. Studies have suggested a cut-point of BNP > or = 100 pg/mL for the diagnosis of HF; however, there is an inverse relation between BNP levels and body mass index. We evaluated differential cut-points for BNP in diagnosing acute HF across body mass index levels to determine whether alternative cut-points can improve diagnosis.


METHODS
The Breathing Not Properly Multinational Study was a 7-center, prospective study of 1586 patients who presented to the Emergency Department with acute dyspnea. B-type natriuretic peptide was measured on arrival. Height and weight data were available for 1368 participants. The clinical diagnosis of HF was adjudicated by 2 independent cardiologists who were blinded to BNP results.


RESULTS
Heart failure was the final diagnosis in 46.1%. Mean BNP levels (pg/mL) in lean, overweight/obese, and severely/morbidly obese patients were 643, 462, and 247 for patients with acute HF, and 52, 35, and 25 in those without HF, respectively (P < .05 for all comparisons except 35 vs 25). B-type natriuretic peptide cut-points to maintain 90% sensitivity for a HF diagnosis were 170 pg/mL for lean subjects, 110 pg/mL for overweight/obese subjects, and 54 pg/mL in severely/morbidly obese patients.


CONCLUSIONS
Body mass index influences the selection of cut-points for BNP in diagnosing acute HF. A lower cut-point (BNP > or = 54 pg/mL) should be used in severely obese patients to preserve sensitivity. A higher cut-point in lean patients (BNP > or = 170 pg/mL) could be used to increase specificity.
Daniels
Lori B
LB
University of California, San Diego, CA, USA.
Clopton
Paul
P
Bhalla
Vikas
V
Krishnaswamy
Padma
P
Nowak
Richard M
RM
McCord
James
J
Hollander
Judd E
JE
Duc
Philippe
P
Omland
Torbjørn
T
Storrow
Alan B
AB
Abraham
William T
WT
Wu
Alan H B
AH
Steg
Philippe G
PG
Westheim
Arne
A
Knudsen
Cathrine Wold
CW
Perez
Alberto
A
Kazanegra
Radmila
R
Herrmann
Howard C
HC
McCullough
Peter A
PA
Maisel
Alan S
AS
D000208:Acute Disease; D000368:Aged; D015992:Body Mass Index; D015331:Cohort Studies; D004417:Dyspnea / Q000150:complications; D005260:Female; D006333:Heart Failure / Q000097:blood* / Q000150:complications / Q000175:diagnosis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015337:Multicenter Studies as Topic; D020097:Natriuretic Peptide, Brain / Q000097:blood*; D009765:Obesity / Q000097:blood* / Q000150:complications / Q000473:pathology / Q000503:physiopathology; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D016037:Single-Blind Method
D020097:Natriuretic Peptide, Brain