Department of Anesthesiology, Amsterdam University Medical Centers, Vrije Universiteit Amsterdam, Location VUmc, Amsterdam, The Netherlands.
Department of Anaesthesia and Intensive Care Medicine, Third Faculty of Medicine, Charles University, FNKV University Hospital, Prague, Czech Republic.
Scand J Trauma Resusc Emerg Med. 2024 Oct 25;32(1):104. doi: 10.1186/s13049-024-01276-0.
The Advanced Trauma Life Support classification (ATLS) of hypovolemic shock is a widely used teaching and treatment reference in emergency medicine, but oversimplifies clinical reality. A decade ago, a landmark study compared vital parameters to base deficit (BD) in trauma patients. The investigators concluded that BD had higher accuracy to detect the need for early blood product administration. BD was subsequently introduced in the ATLS shock classification and has since been widely accepted as a laboratory standard for hypovolemia. The aim of this study is to investigate whether a methodological bias may have inadvertently contributed to the study's results and interpretation.
In the current study, we replicate the original study by simulating a cohort of trauma patients with randomly generated data and applying the same methodological strategies. First, a predefined correlation between all predictor variables (vital parameters and BD) and outcome variable (transfusion) was set at 0.55. Then, in accordance with the methods of the original study we created a composite of ATLS parameters (highest class amongst heart rate, systolic blood pressure, and Glasgow Coma Scale) and compared it with BD for resulting transfusion quantity. Given the preset correlations between predictors and outcome, no predictor should exhibit a stronger association unless influenced by methodological bias.
Applying the original imbalanced grouping and composite allocation strategies caused a systematic overestimation of shock class for traditional ATLS parameters, favoring the association between BD and transfusion. This effect persisted when the correlation between BD and transfusion was set substantially worse (rho = 0.3) than the correlation between ATLS parameters and transfusion (rho = 0.8).
In this fully reproducible simulation, we confirm the inadvertent presence of methodological bias. It is physiologically reasonable to include a metabolic parameter to classify hypovolemic shock, but more evidence is needed to support widespread and preferred use of BD.
创伤生命支持（ATLS）分类中的低血容量性休克是急诊医学中广泛使用的教学和治疗参考，但过于简化了临床实际情况。十年前，一项具有里程碑意义的研究比较了创伤患者的重要参数与基础缺陷（BD）。研究人员得出结论，BD 具有更高的准确性来检测早期血液制品给药的需求。BD 随后被引入 ATLS 休克分类，并已被广泛接受为低血容量的实验室标准。本研究旨在调查方法学偏差是否可能无意中促成了研究结果和解释。
在本研究中，我们通过模拟一组具有随机生成数据的创伤患者，并应用相同的方法学策略来复制原始研究。首先，在所有预测变量（重要参数和 BD）和结局变量（输血）之间预先设定相关性为 0.55。然后，根据原始研究的方法，我们创建了 ATLS 参数的组合（心率、收缩压和格拉斯哥昏迷量表中最高的类别），并将其与 BD 进行比较，以比较输血量。由于预测因子与结局之间存在预设的相关性，除非受到方法学偏差的影响，否则没有预测因子应该表现出更强的相关性。
应用原始不平衡分组和复合分配策略会导致传统 ATLS 参数对休克类别的系统高估，有利于 BD 与输血之间的关联。当 BD 与输血之间的相关性设定得明显更差（rho = 0.3）而不是 ATLS 参数与输血之间的相关性（rho = 0.8）时，这种影响仍然存在。
在这项完全可重现的模拟中，我们确认了方法学偏差的存在。包含代谢参数来分类低血容量性休克在生理上是合理的，但需要更多证据来支持 BD 的广泛和优先使用。
