Thomson J M, Taberner D A, Poller L
United Kingdom Reference Laboratory for Anticoagulant Reagents and Control, Withington Hospital, Manchester.
J Clin Pathol. 1990 Aug;43(8):679-84. doi: 10.1136/jcp.43.8.679.
Current performance in the prothrombin time (PT) of the two main United Kingdom coagulometer/thromboplastin systems was assessed in a field survey. Twenty abnormal samples covering a wide spectrum of International Normalised Ratio (INR) were distributed to users of the KC4/KC10 and Coag-a-Mate instruments. Coagulometer results were compared with those of the manual method. A substantial minority with each system showed good agreement with the manual reference values. There was, however, a considerable variation between instruments, meaningful in clinical terms, evidenced by varying regression slopes and local system International Sensitivity Indices (ISI). For intense anticoagulation (3.0 to 4.5 INR) a larger dose of warfarin is needed with the Coag-a-Mate than with the KC instruments. With a manual INR of 4.0 the KC instruments tended to give longer PT (mean INR + 0.3); the Coag-a-Mate PT was generally shorter (mean INR -0.1). With both systems the mean normal PT were shorter than the manual but the degree of shortening did not parallel that of the abnormal samples. This effect undermines the use of a simple prothrombin ratio and of an INR value derived from it, based on a manual ISI. The use of a system related ISI cannot, however, be recommended until local instrument variables are controlled.
在一项现场调查中，对英国两种主要凝血仪/凝血活酶系统的凝血酶原时间（PT）当前性能进行了评估。向使用KC4/KC10和Coag-a-Mate仪器的用户分发了20份涵盖广泛国际标准化比值（INR）范围的异常样本。将凝血仪结果与手工方法的结果进行比较。每个系统都有相当一部分结果与手工参考值高度一致。然而，仪器之间存在相当大的差异，从临床角度来看具有重要意义，这表现为回归斜率和本地系统国际敏感指数（ISI）各不相同。对于高强度抗凝（INR为3.0至4.5），与KC仪器相比，Coag-a-Mate需要更大剂量的华法林。当手工INR为4.0时，KC仪器往往给出更长的PT（平均INR + 0.3）；Coag-a-Mate的PT通常更短（平均INR -0.1）。对于这两种系统，平均正常PT均短于手工测量值，但缩短程度与异常样本的缩短程度并不平行。这种效应削弱了基于手工ISI的简单凝血酶原比值及其衍生的INR值的应用。然而，在本地仪器变量得到控制之前，不建议使用与系统相关的ISI。
