Correlation between chest radiograph and B-type natriuretic peptide in congestive heart failure

Abstract

Study objectives: B-type natriuretic peptide (BNP) values greater than 400 pg/mL have been shown to have high positive predictive value (90%) for the diagnosis of clinical congestive heart failure (CHF). It may be possible for a patient who presents to the emergency department (ED) with dyspnea to forgo chest radiograph, which may occur if there is a cutoff value of BNP with enough sensitivity and specificity to reliably predict a positive confirmatory chest radiograph. We determine the correlation between elevated BNP levels and a positive confirmatory chest radiograph for CHF. Methods: This was a 1-year retrospective review of all ED patients with chief complaints of dyspnea or leg edema, BNP greater than 400 pg/mL, and final diagnosis of CHF or pulmonary edema. Data included age, sex, medical history, BNP levels, and chest radiograph findings. Descriptive statistics were analyzed and receiver operating characteristic (ROC) curve was calculated for the probability of a positive confirmatory chest radiograph against the BNP value. Results: Fifty-four patients were included, with a mean age of 81.7 years (SD 8.2 years); 64.8% were women. Dyspnea was the chief complaint in 94.4% of patients, and the mean BNP was 1,493 pg/mL (SD 1,106). Only 68.5% of patients had a positive confirmation of CHF on chest radiograph. ROC curve showed no cutoff value of BNP associated with a positive chest radiograph and overall weak correlation (area under the curve=.547; 95% confidence interval .359 to .735). Conclusion: There is weak correlation between the level of BNP and a positive confirmation of CHF or pulmonary edema on chest radiograph. There is no cutoff value of BNP that can reliably predict a positive chest radiograph.