The Optimal Cut-off Value of Plasma BNP to Differentiate Heart Failure in the Emergency Department in Japanese Patients with Dyspnea

Objective In the emergency department, it is sometimes difficult to differentiate heart failure (HF) from other diseases (e.g., respiratory diseases) in patients who develop dyspnea. The plasma B-type natriuretic peptide (BNP) levels increase in patients with HF, and various levels are associated with specific New York Heart Association classes. Although the diagnosis of HF should not be made based only on the plasma BNP levels, the identification of a cut-off value for BNP to diagnose HF would be helpful. Methods Patients admitted to the emergency department of our hospital with dyspnea between January 2010 and December 2011 were retrospectively reviewed. The patients whose estimated glomerular filtration rate was less than 30 mL/min/1.73 m(2) were excluded. Patients were divided into two groups: those with HF (n=131) and those without HF (n=138). The cut-off value for BNP was determined by the receiver-operating characteristic curve. Results The area under the curve of this curve was 0.934. The optimal cut-off point for detection of HF was 234 pg/mL. The sensitivity and specificity were 87.0% and 85.5%, respectively. The fifth and 95th percentiles of the HF group were 132.2 and 2,420.8 pg/mL, respectively. Those of the non-HF group were 9.7 and 430.2 pg/mL, respectively. Conclusion Our study suggests that a plasma BNP level cut-off value of 234 pg/mL can be used to detect HF in the emergency department.