Chantarangkul V, Tripodi A, Cesana B M, Mannucci P M
Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Department of Internal Medicine, University, Milano, Italy.
Thromb Haemost. 1999 Dec;82(6):1621-6.
Calibration with lyophilized calibrant plasmas certified in terms of PT with International Reference Preparations for thromboplastin has been proposed to minimize the effect of coagulometers on the INR. Aim of this study was to test the ability of local calibration with lyophilized calibrant plasmas, combined with a modified statistical approach, to improve the interlaboratory variability of the INR measured on two test plasmas (one coumarin and one artificially-depleted) by participants in the External Quality Assessment Scheme (EQAS). Sets of lyophilized calibrant and test plasmas were sent to the participants in the EQAS, who were asked to determine PT with their own reagent/ instrument combination (local system). Results were returned as PT together with information on the type of local system, the stated International Sensitivity Index (ISI) and the geometric mean of PTs determined by testing with the local system fresh plasmas from 20 healthy subjects. Ninety-two participants using 9 and 11 brands of reagents and instruments returned results. The CV of the INR determined with the stated ISI for the coumarin (Mean INR = 4.39) and artificially-depleted (Mean INR = 4.23) test plasmas were 11.2% and 10.3% and were reduced on the average by 34% and 54%, respectively, when the INR was calculated with the local ISI. In conclusions, results from this field study involving laboratories and testing systems representative of the real situation in oral anticoagulant monitoring in our country, indicate that local calibration by artificially-depleted plasmas, combined with the proposed statistical approach, is suitable to improve the interlaboratory agreement on the INR.
有人提议使用经凝血活酶国际参考制剂认证的冻干校准血浆进行校准，以尽量减少凝血仪对国际标准化比值（INR）的影响。本研究的目的是测试冻干校准血浆的局部校准能力，并结合改进的统计方法，以改善外部质量评估计划（EQAS）参与者在两种测试血浆（一种香豆素血浆和一种人工耗尽血浆）上测得的INR的实验室间变异性。将冻干校准血浆和测试血浆样本发送给EQAS的参与者，要求他们使用自己的试剂/仪器组合（本地系统）测定凝血酶原时间（PT）。结果以PT形式返回，并附带有关本地系统类型、规定的国际敏感指数（ISI）以及使用本地系统对20名健康受试者的新鲜血浆进行测试所确定的PT几何平均值的信息。92名使用9种和11种试剂及仪器品牌的参与者返回了结果。使用规定ISI测定的香豆素（平均INR = 4.39）和人工耗尽（平均INR = 4.23）测试血浆的INR变异系数（CV）分别为11.2%和10.3%，当使用本地ISI计算INR时，平均分别降低了34%和54%。总之，这项涉及代表我国口服抗凝剂监测实际情况的实验室和检测系统的现场研究结果表明，人工耗尽血浆的局部校准结合所提议的统计方法，适合改善实验室间在INR方面的一致性。
