1h血清乳酸水平与ICU重症患者30d病死率的相关研究

Relationship between "1-hour serum lactate" level and 30-day mortality in critical care patients in intensive care unit

目的探讨1 h血清乳酸(Lac)水平与重症监护病房(ICU)重症患者30 d病死率的关系。方法采用回顾性观察性队列研究方法,从美国重症监护医学信息数据库(MIMIC-Ⅲ)中收集首次入住ICU 1 h内测定过Lac水平的成人(年龄≥16岁)重症患者的临床资料。根据1 h Lac水平将患者分为<2 mmol/L组、2~4 mmol/L组、>4 mmol/L组,分析患者基线特征。采用多变量Logistic回归分析评估1 h Lac水平与30 d病死率之间的关系。用受试者工作特征曲线(ROC)分析1 h Lac水平对重症患者30 d病死率的预测价值,并根据最佳截断值分组,绘制30 d Kaplan-Meier生存曲线。此外,对各分类变量分层进行敏感性分析。结果共纳入3969例ICU重症患者,30 d死亡673例,30 d总病死率为16.96%。1 h Lac<2 mmol/L 1664例,1 h Lac 2~4 mmol/L 1588例,1 h Lac>4 mmol/L 717例,3组患者年龄、入住ICU时间、入住ICU类型、心率、白细胞计数、血红蛋白、血肌酐、序贯器官衰竭评分(SOFA)、呼吸机使用、血管活性药物使用以及主要诊断差异均有统计学意义。多变量Logistic回归分析显示,1 h Lac每增加1 mmol/L,重症患者30 d病死率将增加0.24倍〔优势比(OR)=1.24,95%可信区间(95%CI)为1.19~1.29,P<0.0001〕。ROC曲线分析显示,1 h Lac预测重症患者30 d病死率的ROC曲线下面积(AUC)为0.694(95%CI为0.669~0.718),最佳截断值为3.35 mmol/L时,敏感度为0.499,特异度为0.779,阳性似然比为2.260,阴性似然比为0.643。根据1 h Lac最佳截断值将患者分为高乳酸组(≥3.35 mmol/L)和低乳酸组(<3.35 mmol/L),其30 d病死率分别为31.58%(336/1064)和11.60%(337/2905),Kaplan-Meier生存曲线显示,高乳酸组30 d累积存活率显著低于低乳酸组(Log-rank检验:χ^2=247.72,P<0.0001)。多元回归分析显示,考虑到年龄、入住ICU时间、入住ICU类型、血红蛋白水平、白细胞计数、血管活性药物使用、呼吸机使用及主要诊断等因素,高乳酸组30 d病死率是低乳酸组的2.34倍(OR=2.34,95%CI为1.90~2.88,P<0.0001)。对所有分类变量进行分层分析显示,1 h Lac与30 d病死率的关系基本保持一致。结论在ICU重症患者中,1 h Lac水平与30 d病死率密切相关;1 h Lac水平超过3.35 mmol/L的重症患者死亡风险显著增加。

Objective To investigate the relationship between 1-hour lactate(1 h Lac)and 30-day mortality in critical care patients in intensive care unit(ICU).Methods A retrospective,observational cohort study was performed with adult critical patients(age≥16 years old)having lactate records within 1 hour after ICU admission from Medical Information Mart for Intensive Care-Ⅲdatabase(MIMIC-Ⅲ).According to the 1 h Lac level,the patients were divided into three groups:<2 mmol/L,2-4 mmol/L,and>4 mmol/L groups.The baseline characteristics were analyzed.Multivariable Logistic regression analysis was performed to assess the association between 1 h Lac and 30-day mortality.The receiver operating characteristic(ROC)curve was used to analyze the predictive value of 1 h Lac for 30-day mortality,and Kaplan-Meier survival curve was performed according to the best cut-off value.In addition,sensitivity analysis was carried out for each classification variable.Results A total of 3969 ICU patients were included,with 673 died in 30 days,and the total mortality was 16.95%.There were 1664,1588,717 patients in Lac<2 mmol/L,2-4 mmol/L and>4 mmol/L group,respectively.There were significant differences in age,ICU duration,ICU type,heart rate,leukocyte count,hemoglobin,creatinine,sequential organ failure score(SOFA),ventilator application,vasoactive drug use and main diagnosis among the three groups.Multivariable Logistic regression analysis showed that a 1 mmol/L increment in Lac was associated with 0.24 times higher risk of 30-day mortality[odds ratio(OR)=1.24,95%confidence interval(95%CI)was 1.19-1.29,P<0.0001].ROC curve analysis showed that the area under ROC curve(AUC)of 1 h Lac for predicting 30-day mortality of severe patients was 0.694(95%CI was 0.669-0.718).The cut-off value was 3.35 mmol/L with sensitivity of 0.499 and specificity of 0.779,whilst positive likelihood ratio was 2.260,and negative likelihood ratio was 0.643.According to the cut-off value of 1 h Lac,the patients were divided into high lactate group(≥3.35 mmol/L)and low lactate group(<3.35 mmol/L).In the two subgroups,30-day mortality was 31.58%(336/1064)and 11.60%(337/2905),respectively.The Kaplan-Meier survival curve showed that the 30-day cumulative survival rate of high lactate group was significantly lower than that of low lactate group(Log-rank test:χ^2=247.72,P<0.0001).Multiple Logistic regression analysis showed that the 30-day mortality rate of high lactate group was 2.34 times that the level of low lactate group(OR=2.34,95%CI was 1.90-2.88,P<0.0001),after the adjustment of age,time of admission,type of ICU,hemoglobin,leukocyte count,use of vasopressor,use of ventilator and main diagnosis of patients.Stratified analysis showed that the relationship between 1 h Lac and 30-day mortality was stable.Conclusions 1 h Lac is associated with 30-day mortality in critical care patients.The risk of death was significantly increased in critically ill patients with 1 h Lac higher than 3.35 mmol/L.