Effect of body mass index on diagnostic and prognostic usefulness of amino-terminal pro-brain natriuretic peptide in patients with acute dyspnea.
BACKGROUND
Amino (N)-terminal pro-brain natriuretic peptide (NT-proBNP) testing is useful for diagnostic and prognostic evaluation in patients with dyspnea. An inverse relationship between body mass index (BMI); (calculated as weight in kilograms divided by height in meters squared) and NT-proBNP concentrations has been described.


METHODS
One thousand one hundred three patients presenting to the emergency department with acute dyspnea underwent analysis. Patients were classified into the following 3 BMI categories: lean (<25.0), overweight (25.0-29.9), and obese (>/=30.0).


RESULTS
The NT-proBNP concentrations in the overweight and obese groups were significantly lower than in the lean patients, regardless of the presence of acute heart failure (P<.001). The positive likelihood ratio for an NT-proBNP-based diagnosis of acute heart failure was 5.3 for a BMI lower than 25.0, 13.3 for a BMI of 25.0 to 29.9, and 7.5 for a BMI of 30.0 or higher. A cut point of 300 ng/L had very low negative likelihood ratios in all 3 BMI categories (0.02, 0.03, and 0.08, respectively). Among decedents, the NT-proBNP concentrations were lower in the overweight and obese patients compared with the lean subjects (P<.001). Nonetheless, a single cut point of 986 ng/L strongly predicted 1-year mortality across the 3 BMI strata, regardless of the presence of acute heart failure (hazard ratios, 2.22, 3.06, and 3.69 for BMIs of <25.0, 25.0-29.9, and >/=30.0, respectively; all P<.004); the risk associated with a high NT-proBNP concentration was detected early and was sustained to a year after baseline in all 3 BMI strata (all P<.001).


CONCLUSIONS
In patients with and without acute heart failure, the NT-proBNP concentrations are relatively lower in overweight and obese patients with acute dyspnea. Despite this, the NT-proBNP concentration retains its diagnostic and prognostic capacity across all BMI categories.
Bayes-Genis
Antoni
A
Department of Cardiology, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma, Barcelona, Spain.
Lloyd-Jones
Donald M
DM
van Kimmenade
Roland R J
RR
Lainchbury
John G
JG
Richards
A Mark
AM
Ordoñez-Llanos
Jordi
J
Santaló
Miquel
M
Pinto
Yigal M
YM
Januzzi
James L
JL
D000208:Acute Disease; D000368:Aged; D015415:Biomarkers / Q000097:blood; D015992:Body Mass Index; D003937:Diagnosis, Differential; D004417:Dyspnea / Q000097:blood* / Q000175:diagnosis* / Q000209:etiology; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000097:blood / Q000150:complications; D006801:Humans; D008297:Male; D008875:Middle Aged; D020097:Natriuretic Peptide, Brain / Q000097:blood*; D009765:Obesity / Q000097:blood / Q000150:complications; D010446:Peptide Fragments / Q000097:blood*; D011379:Prognosis; D011498:Protein Precursors; D012307:Risk Factors
D015415:Biomarkers; D010446:Peptide Fragments; D011498:Protein Precursors; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain