Cutpoints for using N-terminal pro–B-type natriuretic peptide (NT-proBNP) to diagnose heart failure (HF) in the ED were validated in a recent study.
The study used data from 1,461 dyspneic patients who presented to 19 EDs in North America and had blood drawn for subsequent NT-proBNP measurement. Overall, 19% were determined to have acute HF, and the area under the receiver-operating characteristic curve for diagnosis was 0.91 (95% CI, 0.90 to 0.93; P<0.001). Results were published by the Journal of the American College of Cardiology on March 12.
Researchers evaluated age-stratified cutoffs for diagnosing HF: 450 pg/mL for patients under 50 years, 900 pg/mL for 50 to 75 years, and 1,800 pg/mL for over 75 years. The sensitivity, specificity, and positive predictive values for these age-stratified cutoffs were 85.7%, 93.9%, and 53.6%; 79.3%, 84.0%, and 58.4%; and 75.9%, 75.0%, and 62.0%, respectively. The overall positive likelihood ratio across age-dependent cutoffs was 5.99 (95% CI, 5.05 to 6.93), and individual ratios for the age-dependent cutoffs were 14.08, 4.95, and 3.03, respectively. Using 300 pg/mL as a cutpoint to rule out heart failure had a sensitivity of 93.9% and a negative predictive value of 98.0%. The negative likelihood ratio was 0.09 (95% CI, 0.05 to 0.13).
The study authors noted that although these NT-proBNP cutpoints are widely used in clinical practice, they had not previously been prospectively validated in U.S. patients and that differences in guidelines and FDA approvals causes confusion about them. “Results of the study indicate excellent performance of NT-proBNP to identify or exclude acute HF, and support the utility of the widely-used age-stratified diagnostic approach for its use, while also verifying high [negative predictive value] of 300 pg/ml to exclude acute HF,” they said. The authors did caution that cutpoints are specific to the setting of care.
An accompanying editorial comment agreed that the results showed the utility of NT-proBNP but added that “they do not overcome the wide ‘gray zones' between rule-in and -out values, in which the test is limited and must be interpreted in the context of age and renal function” and the study “demonstrated that no single cutpoint can be applied in clinical practice.”