重症监护病房患者血清N末端B型利钠肽水平对预后评估的意义

The significance of serum N-terminal pro-brain natriuretic peptide levels for prognosis of patients in intensive care unit

目的 评价重症监护病房（ICU）危重患者血清N末端B型利钠肽（NT-proBNP）水平升高对住院30 d死亡风险的影响.方法 采用回顾性研究方法,选择2012年6月至2013年10月由天津市第一中心医院急诊科收住ICU的危重患者480例,记录其入院时基本临床资料及入院后急性生理学与慢性健康状况评分系统Ⅱ（APACHEⅡ）评分,检测入院24 h内血常规、血生化及血清NT-proBNP水平.以入院30 d转归分为死亡组和存活组,比较两组患者的基本资料和临床指标,进行影响预后的单因素分析.同时将所有患者NT-proBNP按照四分位法分为NT-proBNP＜ 280 ng/L（Q1组）、280 ng/L≤NT-proBNP＜1 200 ng/L（Q2组）、1 200 ng/L≤NT-proBNP＜1 990 ng/L（Q3组）、1 990 ng/L≤NT-proBNP＜4 700 ng/L（Q4组）4组,应用Cox回归分析影响预后的独立危险因素.绘制受试者工作特征曲线（ROC曲线）,对比APACHEⅡ评分、NT-proBNP对预后的判断能力.对不同NT-proBNP水平患者进行Kaplan-Meier生存曲线分析.结果 单因素分析表明,年龄、APACHEⅡ评分、肌酐、NT-proBNP、感染5项指标对预后有影响.NT-proBNP 1 200～4 700 ng/L（Q3、Q4）和APACHEⅡ评分＞20分为预测预后的独立危险因素[Q3的相对危险度（RR）=3.624,95％可信区间（95％CI）为1.258～10.138; Q4的RR=5.059,95％CI为3.202～9.993; APACHEⅡ评分＞20分的RR=2.987,95％CI为1.345～5.823].APACHEⅡ评分、血清NT-proBNP预测预后的ROC曲线下面积（AUC）相近,分别为0.831（95％CI为0.778～0.884）、0.876（95％CI为0.827～0.925）;NT-proBNP预测病死率的临界值为1 250 ng/L.Kaplan-Meier生存曲线分析,与Q1组比较,Q2、Q3、Q4组患者累积生存率均有降低（26.5％、25.4％、16.2％比29.6％）,以Q4组降低最显著（x2=122.920,P＜0.05）.结论 ICU危重患者血清NT-proBNP水平升高表明疾病严重,可成为评价危重病患者发生死亡事件的独立危险因素.

Objective To assess the significance of elevated serum N-terminal pro-brain natriuretic peptide （NT-proBNP） levels in predicting 30-day mortality rate for patients in intensive care unit （ICU）.Methods A retrospective study was conducted.The clinical data of 480 patients admitted to ICU in Tianjin First Center Hospital from June 2012 to October 2013 were studied.The characteristics of patients were recorded,the acute physiology and chronic health evaluation Ⅱ （APACHE I） score was calculated,and the routine blood tests,blood biochemistry,and serum NT-proBNP level within 24 hours after admission were determined.Patients were divided into non-survival and survival groups according to 30-day outcome,and the characteristics and clinical parameters were compared between two groups,and single factor analysis affecting prognosis was analyzed.All patients were divided into four groups according to four percentile method as NT-proBNP＜280 ng/L （group Q1）,280 ng/L≤NT-proBNP＜ 1 200 ng/L （group Q2）,1 200 ng/L≤NT-proBNP＜1 990 ng/L （group Q3）,1 990 ng/L≤NT-proBNP＜4 700 ng/L （group Q4）.A Cox regression analysis was used to test the independence of the predictors.A receiver operator characteristic curve （ROC curve） was plotted to compare the power of APACHE Ⅱ score and NT-proBNP in predicting the outcome.Kaplan-Meier analysis was used to assess survival rate among different NT-proBNP patients.Results By single factor analysis it was shown that age,APACHE Ⅱ score,creatinine,NT-proBNP and severe infection were those influencing the outcome.NT-proBNP 1 200-4 700 ng/L （groups Q3 and Q4） and APACHE Ⅱ score ＞20 were independent risk factors for predicting outcome [relative risk （RR） for group Q3 was 3.624,95％ credibility interval （95％CI） was 1.258-10.138; RR for group Q4 was 5.059,95％ CI was 3.202-9.993; RR for APACHE Ⅱ score ＞20 was 2.987,95％ CI was 1.345-5.823].The area under the ROC curve （AUC） for APACHE Ⅱ score and serum NT-proBNP was similar,and it was 0.831 （95％CI 0.778-0.884） and 0.876 （95％CI 0.827-0.925）,respectively.The cut-off value of NT-proBNP for predicting mortality was 1 250 ng/L.Kaplan-Meier analysis showed that groups of Q2,Q3 and Q4 had lower cumulative survival rate compared with group Q1 （26.5％,25.4％,16.2％ vs.29.6％）,and group Q4 showed most significant extent of lowering of survival rate （x2=122.920,P＜ 0.05）.Conclusion Elevated NT-proBNP level in ICU patients signify severity of the disease,and it is an independent predictor of death of ICU patients.