Houbouyan L L, Goguel A F
Department of Immuno-Hematology, Hospital Ambroise Paré, Boulogne, France.
Am J Clin Pathol. 1997 Jul;108(1):83-9.
The International Normalized Ratio (INR) has not lowered the interlaboratory differences in prothrombin time (PT) values to the extent expected, mainly because of the instrument-dependency of the International Sensitivity Index (ISI) and other factors (eg, accurate determination of the ISI, the normal value used in the PT ratio). The procedure (PPC) using plasma calibrants (reference lyophilized plasmas with assigned activity) has been evaluated since 1977 in nine French national external quality assessment surveys (NEQAS) involving approximately 4,000 laboratories and numerous local thromboplastin technique combinations. The PPC was compared with the conventional procedure (using the manufacturer's ISI), and the efficiency of antivitamin K-calibrated (AK Cal) plasmas from patients receiving oral anticoagulants vs artificially depleted plasma calibrants was also evaluated. The PPC efficiently standardized PTs with AK Cal plasmas, reducing interlaboratory variability (eg, coefficient of variation, 12% to 6% for survey 92 D) and reagent-instrument effects. However, AK Cal plasmas have drawbacks, such as limited supply, cost, and batch-to-batch variability. The artificially depleted plasma calibrants were less efficient, but usable if carefully prepared. The value of this simple procedure is that local practices are considered in the determination of PT, thus correcting for coagulometer effects and avoiding use of the manufacturer's ISI and need for a normal control plasma. These large-scale French surveys have demonstrated the validity of PPC through 15 years of experience and have shown that it offers the best compromise available in PT standardization.
国际标准化比值（INR）并未将凝血酶原时间（PT）值的实验室间差异降低到预期程度，主要是因为国际敏感指数（ISI）依赖仪器以及其他因素（例如，ISI的准确测定、PT比值中使用的正常值）。自1977年以来，在九次法国全国性外部质量评估调查（NEQAS）中对使用血浆校准物（具有指定活性的参考冻干血浆）的程序（PPC）进行了评估，这些调查涉及约4000个实验室以及众多不同的凝血活酶技术组合。将PPC与传统程序（使用制造商的ISI）进行了比较，还评估了接受口服抗凝剂患者的抗维生素K校准（AK Cal）血浆与人工稀释血浆校准物相比的效率。PPC使用AK Cal血浆有效地实现了PT标准化，降低了实验室间的变异性（例如，第92 D次调查的变异系数从12%降至6%）以及试剂-仪器效应。然而，AK Cal血浆存在缺点，如供应有限、成本高以及批次间差异。人工稀释血浆校准物效率较低，但如果精心制备仍可使用。这个简单程序的价值在于，在PT测定中考虑了当地的实际情况，从而校正了凝血仪效应，避免了使用制造商的ISI以及对正常对照血浆的需求。这些大规模法国调查通过15年的经验证明了PPC的有效性，并表明它在PT标准化方面提供了最佳的折衷方案。
