B-type natriuretic peptide in predicting the severity of community-acquired pneumonia.

BACKGROUND Although pneumonia severity index (PSI) is widely used to evaluate the severity of community-acquired pneumonia (CAP), the calculation of PSI is very complicated. The present study aimed to evaluate the role of B-type natriuretic peptide (BNP) in predicting the severity of CAP. METHODS For 202 patients with CAP admitted to the emergency department, BNP levels, cardiac load indexes, inflammatory indexes including C-reactive protein (CRP), white blood cell count (WBC), and PSI were detected. The correlation between the indexes and PSI was investigated. BNP levels for survivor and non-survivor groups were compared, and a receiver operating characteristic (ROC) curve analysis was performed on the BNP levels versus PSI. RESULTS The BNP levels increased with CAP severity (r=0.782, P<0.001). The BNP levels of the high-risk group (PSI classes IV and V) were significantly higher than those of the low-risk group (PSI classes I-III) (P<0.001). The BNP levels were significantly higher in the non-survivor group than in the survivor group (P<0.001). In addition, there were positive correlations between BNP levels and PSI scores (r=0.782, P<0.001). The BNP level was highly accurate in predicting the severity of CAP (AUC=0.952). The optimal cut-off point of BNP level for distinguishing high-risk patients from low-risk ones was 125.0 pg/mL, with a sensitivity of 0.891 and a specificity of 0.946. Moreover, BNP level was accurate in predicting mortality (AUC=0.823). Its optimal cut-off point for predicting death was 299.0 pg/mL, with a sensitivity of 0.675 and a specificity of 0.816. Its negative predictive cut-off value was 0.926, and the positive predictive cut-off value was 0.426. CONCLUSION BNP level is positively correlated with the severity of CAP, and may be used as a biomarker for evaluating the severity of CAP.