Bellest Laurent, Eschwège Valérie, Poupon Raoul, Chazouillères Olivier, Robert Annie
AP-HP, Hôpital St Antoine, Unité d'Hémostase, Université Pierre et Marie Curie, Paris, France.
Hepatology. 2007 Aug;46(2):528-34. doi: 10.1002/hep.21680.
International Normalized Ratio (INR), which standardizes prothrombin time (PT) during oral anticoagulation, has been extended to standardize PT in liver diseases and is included in prognostic models such as the Model for End stage Liver Disease (MELD). However, mechanisms of PT prolongation in liver diseases differ from those involved in oral anticoagulation, and the thromboplastin reagents differ in their sensitivities to these 2 mechanisms. Our aim was to determine whether, in the calibration model for thromboplastins proposed by the World Health Organization, the use of plasmas from patients with liver diseases instead of plasmas from patients on oral anticoagulation could lead to a new INR specific for liver diseases (INR "LD"), achieving a real standardization of PT. First, 5 thromboplastins were calibrated against an international reference using 60 plasmas of patients with liver failure and, in a second step, the variation of PT reported as seconds, the ratio of patient PT to normal PT, INR, and INR"LD" was assessed in 34 other patients. MELD scores were calculated with the INR values obtained with the 5 thromboplastins. Only INR"LD" eliminated variability in PT results observed with the different thromboplastins. The discrepancy between MELD scores were up to 4 and 7 points in 52% and 17% of the patients, respectively.
INR "LD" may provide a common international scale of PT reporting in hepatology. Its adoption would be an important step because of the significant impact on MELD score induced by interlaboratory variability in INR determination.
国际标准化比值（INR）用于在口服抗凝治疗期间标准化凝血酶原时间（PT），现已扩展至用于标准化肝病中的PT，并被纳入诸如终末期肝病模型（MELD）等预后模型中。然而，肝病中PT延长的机制与口服抗凝治疗中涉及的机制不同，并且凝血活酶试剂对这两种机制的敏感性也不同。我们的目的是确定，在世界卫生组织提出的凝血活酶校准模型中，使用肝病患者的血浆而非口服抗凝治疗患者的血浆是否会产生一种针对肝病的新INR（INR“LD”），从而实现PT的真正标准化。首先，使用60份肝衰竭患者的血浆对5种凝血活酶进行国际参考校准，第二步，在另外34名患者中评估以秒为单位报告的PT变化、患者PT与正常PT的比值、INR以及INR“LD”。使用5种凝血活酶获得的INR值计算MELD评分。只有INR“LD”消除了不同凝血活酶观察到的PT结果差异。分别有52%和17%的患者中，MELD评分差异高达4分和7分。
INR“LD”可能为肝病学中PT报告提供一个通用的国际标准。由于INR测定的实验室间差异对MELD评分有重大影响，采用它将是重要的一步。
