Prognostic Value Of NT-proBNP In Septic Patients

Objective: The aim of this study was to evaluate prognostic value of N-terminal pro-B-type natriuretic peptide (NT-proBNP), to evaluate the correlation between NT-proBNP level and APACHEⅡscore in septic patients.Methods: This study was a prospective observational cohort study about prognostic value of NT-proBNP in septic patients. 32 septic patients were divided into two groups according to survival status in 28 days follow up. 24 patients were in the survivors group, and 8 patients were in the nonsurvivors group. Enrolled patients fulfilled the clinical criteria of sepsis which was defined by the 2001 SCCM/ESICM/ACCP/ATS/SIS International Sepsis Definitions Conference. The blood tests for liver function, renal function, electrolytes, blood routine, artery blood gas analysis were drawn on the time point of admission. And the blood samples and sputum samples were preserved to do bacterial culture, fungal culture and drug sensitive test. The blood tests for NT-proBNP analyses were done on the day of admission and 72 hrs thereafter. The NT-proBNP level was determined using chemiluminescent immunoassay. Patients'demographic data for APACHE-Ⅱscore were collected. The measurement data are presented as mean±standard deviation. The measurement data between survivors group and nonsurvivors group were compared using t test. The nonparametric data between survivors group and nonsurvivors group were compared using Mann-Whitney U test and categorical variables using Fisher exact test. To study the influence of clinical data on mortality, One-factor analysis of variance was applied for to detect the contribution of clinical data on mortality. Variables that were significant in the univariate model were tested further using Binary Logistic Regression analysis for independent contribution to mortality. To study the influence of clinical data on NT-proBNP level, the potential confounding factors on NT-proBNP were assessed with Spearman correlation. Those variables that yielded significance in the univariate model were then tested with Multivariate Logistic Regression. The P <0.05 was considered statistically significant in all tests. The analyses were performed using SPSS 11.5 software.Results: NT-proBNP levels on admission were significantly higher in nonsurvivors group (5463.7±4152.3ng/l) compared with survivors group (839.4±1132.0ng/l; P=0.016). 72 hrs later, NT-proBNP levels in nonsurvivors group (5676.1±3937.4ng/l) remained higher than survivors group (843.5±866.3ng/l, P=0.017). In logistic regression analyses, NT-proBNP values on admission and 72 hrs after were independent predictors of mortality (P<0.05). Creatinine (r=0.338, P<0.001), pH of arterial blood (r=0.237, P=0.014), white blood cell (r=0.285, P=0.004), mechanical ventilation(r=0.210, P=0.025), APACHEⅡscore(r=0.745, P< 0.001) had an independent effect on 0h NT-proBNP values, separately.Conclusions: NT-proBNP level correlated positively with the mortality and APACHEⅡscore. It could be a routine clinical biomarker to evaluate prognosis of septic patients. The increased NT-proBNP level could be due to the effect of proinflammatory cytokine which regulate BNP gene expressing. Severity of sepsis, renal function, disturbance of acid-base balance, mechanical ventilation are all related to the increased NT-proBNP level. Therefore, taking all the above multiple factors into account, the clinical significance of NT-proBNP should be evaluated comprehensively , so as to guide the clinical practice better.