title: 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.
abstract: 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.
authors.affiliation: University of California, San Diego, CA, USA.
authors.forename: Lori B
authors.initials: LB
authors.lastname: Daniels
authors.forename: Paul
authors.initials: P
authors.lastname: Clopton
authors.forename: Vikas
authors.initials: V
authors.lastname: Bhalla
authors.forename: Padma
authors.initials: P
authors.lastname: Krishnaswamy
authors.forename: Richard M
authors.initials: RM
authors.lastname: Nowak
authors.forename: James
authors.initials: J
authors.lastname: McCord
authors.forename: Judd E
authors.initials: JE
authors.lastname: Hollander
authors.forename: Philippe
authors.initials: P
authors.lastname: Duc
authors.forename: Torbjørn
authors.initials: T
authors.lastname: Omland
authors.forename: Alan B
authors.initials: AB
authors.lastname: Storrow
authors.forename: William T
authors.initials: WT
authors.lastname: Abraham
authors.forename: Alan H B
authors.initials: AH
authors.lastname: Wu
authors.forename: Philippe G
authors.initials: PG
authors.lastname: Steg
authors.forename: Arne
authors.initials: A
authors.lastname: Westheim
authors.forename: Cathrine Wold
authors.initials: CW
authors.lastname: Knudsen
authors.forename: Alberto
authors.initials: A
authors.lastname: Perez
authors.forename: Radmila
authors.initials: R
authors.lastname: Kazanegra
authors.forename: Howard C
authors.initials: HC
authors.lastname: Herrmann
authors.forename: Peter A
authors.initials: PA
authors.lastname: McCullough
authors.forename: Alan S
authors.initials: AS
authors.lastname: Maisel
mesh_terms: 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
chemical_list: D020097:Natriuretic Peptide, Brain