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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3 969例ICU重症患者，30 d死亡673例，30 d总病死率为16.96%。1 h Lac4 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（n OR）＝1.24，95%可信区间（95%n CI）为1.19～1.29， n P<0.000 1〕。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%n 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%（336/1 064）和11.60%（337/2 905），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：χn 2＝247.72，n P<0.000 1）。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（n OR＝2.34，95%n CI为1.90～2.88，n P<0.000 1）。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。n 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-Ⅲ database (MIMIC-Ⅲ). According to the 1 h Lac level, the patients were divided into three groups: 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 3 969 ICU patients were included, with 673 died in 30 days, and the total mortality was 16.95%. There were 1 664, 1 588, 717 patients in Lac 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 ( n OR) = 1.24, 95% confidence interval (95%n CI) was 1.19-1.29, n P < 0.000 1]. 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% n 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% (336/1 064) and 11.60% (337/2 905), 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: χn 2 = 247.72, n P < 0.000 1). 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 ( n OR = 2.34, 95%n CI was 1.90-2.88, n P < 0.000 1), 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.n 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.