The roles of using B-type natriuretic peptide to predict the severity of community-acquired pneumonia / 中华急诊医学杂志

ABSTRACT

Objective To evaluate the roles of B-type natriuretic peptide (BNP) in predicting the severity of community-acquired pneumonia (CAP) by studying the correlation between them.Methods A total of 202 patients with CAP admitted from December 2011 to December 2012 were enrolled in this study.All these patients were checked with laboratory tests for BNP level,C-reactive protein (CRP),white blood cell count (WBC) as well as other markers needed for obtaining pneumonia severity index (PSI).The differences in BNP levels,CRP levels,and WBC were compared among different degrees of pneumonia severity,and the correlation between BNP levels and PSI was investigated by a linear correlation analysis.The patients enrolled were divided into a high-risk group (defined as Ⅳ-Ⅴ grade of PSI) and a low-risk group (defined as Ⅰ-Ⅲgrade of PSI).Meanwhile,they were also divided into a survivor group and a non-survivor group according to outcomes.BNP levels between the two groups were compared,and a receiver operating characteristic (ROC) curve analysis was performed on the BNP levels versus PSI.Results BNP levels increased with CAP severity (r =0.782,P ＜0.01).The mean level of BNP (263.2 ± 119.6) pg/mLof patients in the high-risk group was significantly higher than that of patients (71.5 ± 54.3) pg/mL in the low-risk group (P ＜ 0.01).The patients in the non-survivor group had significantly higher BNP levels compared to the survivor group [(343.86 ± 125.49) vs.(183.00 ±121.71) pg/mL,P ＜ 0.01].In addition,there were positive correlations between BNP levels and PSI (r =0.782,P＜0.001),between BNP levels and CRP levels (r =0.560,P＜0.01),and between BNP levels and WBC (r =0.513,P＜0.001).The BNP level had a high accuracy in predicting the severity of CAP (AUC =0.952).The optimal cut-off point of BNP level for distinguishing high-risk from low-risk patients was 125.0 pg/mL,with a semitivity of 0.891 and a specificity of 0.946.Moreover,BNP level had a definite accuracy 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 positive predictive value was 0.426.Conclusions BNP level is positively correlated with the severity of CAP.The patient with BNP level above 125.0 pg/mL should be hospitalized immediately and patients with BNP level higher than 299.0 pg/mL are at the high risk of death.Therefore,BNP is a useful biomarker for evaluating the severity of patients with CAP.