Glasmacher Stella Andrea, Stones William
School of Medicine, University of St Andrews, Fife, KY16 9TF, UK.
Malawi College of Medicine, Blantyre, Malawi.
BMC Anesthesiol. 2016 Aug 30;16(1):68. doi: 10.1186/s12871-016-0241-y.
Lactate concentration is a robust predictor of mortality but in many low resource settings facilities for its analysis are not available. Anion gap (AG), calculated from clinical chemistry results, is a marker of metabolic acidosis and may be more easily obtained in such settings. In this systematic review and meta-analysis we investigated whether the AG predicts mortality in adult patients admitted to critical care settings.
We searched Medline, Embase, Web of Science, Scopus, The Cochrane Library and regional electronic databases from inception until May 2016. Studies conducted in any clinical setting that related AG to in-hospital mortality, in-intensive care unit mortality, 31-day mortality or comparable outcome measures were eligible for inclusion. Methodological quality of included studies was assessed using the Quality in Prognostic Studies tool. Descriptive meta-analysis was performed and the I(2) test was used to quantify heterogeneity. Subgroup analysis was undertaken to identify potential sources of heterogeneity between studies.
Nineteen studies reporting findings in 12,497 patients were included. Overall, quality of studies was poor and most studies were rated as being at moderate or high risk of attrition bias and confounding. There was substantial diversity between studies with regards to clinical setting, age and mortality rates of patient cohorts. High statistical heterogeneity was found in the meta-analyses of area under the ROC curve (I(2) = 99 %) and mean difference (I(2) = 97 %) for the observed AG. Three studies reported good discriminatory power of the AG to predict mortality and were responsible for a large proportion of statistical heterogeneity. The remaining 16 studies reported poor to moderate ability of the AG to predict mortality. Subgroup analysis suggested that intravenous fluids affect the ability of the AG to predict mortality.
Based on the limited quality of available evidence, a single AG measurement cannot be recommended for risk stratification in critically ill patients. The probable influence of intravenous fluids on AG levels renders the AG an impractical tool in clinical practice. Future research should focus on increasing the availability of lactate monitoring in low resource settings.
CRD42015015249 . Registered on 4th February 2015.
乳酸浓度是死亡率的有力预测指标，但在许多资源匮乏地区，缺乏分析乳酸的设备。根据临床化学结果计算得出的阴离子间隙（AG）是代谢性酸中毒的一个指标，在这些地区可能更容易获得。在这项系统评价和荟萃分析中，我们调查了AG是否能预测入住重症监护病房的成年患者的死亡率。
我们检索了Medline、Embase、Web of Science、Scopus、Cochrane图书馆以及地区电子数据库，检索时间从建库至2016年5月。纳入任何临床环境中有关AG与住院死亡率、重症监护病房死亡率、31天死亡率或类似结局指标相关性的研究。使用预后研究质量工具评估纳入研究的方法学质量。进行描述性荟萃分析，并使用I²检验量化异质性。进行亚组分析以确定研究间异质性的潜在来源。
纳入了19项报告12497例患者研究结果的研究。总体而言，研究质量较差，大多数研究被评为存在中度或高度失访偏倚和混杂风险。在临床环境、患者队列的年龄和死亡率方面，研究之间存在很大差异。在AG的ROC曲线下面积（I² = 99%）和均值差（I² = 97%）的荟萃分析中发现了高度统计学异质性。三项研究报告AG对预测死亡率具有良好的辨别力，并且是造成大部分统计学异质性的原因。其余16项研究报告AG预测死亡率的能力较差至中等。亚组分析表明静脉输液会影响AG预测死亡率的能力。
基于现有证据质量有限，不建议将单次AG测量用于危重症患者的风险分层。静脉输液对AG水平的可能影响使得AG在临床实践中成为一种不实用的工具。未来的研究应侧重于提高资源匮乏地区乳酸监测的可及性。
PROSPERO注册号：CRD42015015249。于2015年2月4日注册。
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