Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada; Canadian Blood Services, Medical Affairs and Innovation, Toronto, Ontario, Canada.
Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada; Department of Laboratory Medicine & Molecular Diagnostics, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada.
J Thromb Haemost. 2024 Aug;22(8):2184-2194. doi: 10.1016/j.jtha.2024.05.013. Epub 2024 May 23.
Prothrombin time (PT) and its derivative international normalized ratio (INR) are frequently ordered to assess the coagulation system. Plasma transfusion to treat incidentally abnormal PT/INR is a common practice with low biological plausibility and without credible evidence, yet INR targets appear in major clinical guidelines and account for the majority of plasma use at many institutions. In this article, we review the historical origins of INR targets. We recount historical milestones in the development of the PT, discovery of vitamin K antagonists (VKAs), motivation for INR standardization, and justification for INR targets in patients receiving VKA therapy. Next, we summarize evidence for INR testing to assess bleeding risk in patients not on VKA therapy and plasma transfusion for treating mildly abnormal INR to prevent bleeding in these patients. We conclude with a discussion of the parallels in misunderstanding of historic PT and present-day INR testing with lessons from the past that might help rationalize plasma transfusion in the future.
凝血酶原时间（PT）及其衍生的国际标准化比值（INR）常用于评估凝血系统。为了治疗偶然出现的异常 PT/INR，输注血浆是一种常见的做法，但这种做法的生物学依据不足，也缺乏可信的证据，然而 INR 目标却出现在主要的临床指南中，并在许多机构中占血浆使用的大部分。在本文中，我们回顾了 INR 目标的历史起源。我们叙述了 PT 的发展历程中的历史里程碑、维生素 K 拮抗剂（VKAs）的发现、INR 标准化的动机以及 VKA 治疗患者中 INR 目标的合理性。接下来，我们总结了 INR 检测在评估未接受 VKA 治疗的患者出血风险以及治疗轻度异常 INR 以预防这些患者出血时输注血浆的证据。最后，我们讨论了对历史悠久的 PT 和现代 INR 检测的误解之间的相似之处，并从过去吸取了一些经验教训，这些经验教训可能有助于将来合理使用血浆。
