The relationships among B-type natriuretic peptide (BNP) levels, body mass index (BMI), and congestive heart failure (CHF) as an emergency diagnosis are unknown.
Of 1586 participants in the Breathing Not Properly Multinational Study who had acute dyspnea, 1369 (86.3%) had BNP values and self-reported height and weight. Two independent cardiologists masked to the BNP results adjudicated the final diagnosis.
Congestive heart failure was found in 46% of participants. Individuals with higher BMIs were younger and had more frequent edema on examination but were equally as likely to have CHF vs noncardiac sources of dyspnea. A nearly 3-fold difference was seen in mean ± SD BNP values at the low and high extremes of the BMI groupings (516.7 ± 505.9 vs 176.3 ± 270.5 pg/mL, respectively; P< .001). The correlations between BMI and log BNP among those with and without CHF were r = −0.34 and r = −0.21, respectively (P< .001 for both). Multivariate analysis for the outcome of log BNP among a small subset with CHF (n = 62) found that Framingham score (P = .002), estimated glomerular filtration rate (P = .007), female sex (P = .03), New York Heart Association functional class (P = .09), and third heart sound (P = .08) were independent predictors. However, BMI was not found to be independently related to log BNP (P = .59).
In patients with and without CHF, BNP levels are inversely related to BMI. When considering demographics, severity of disease, and renal function, BMI is not independently related to BNP levels in a small subgroup when detailed information about CHF severity is known.