van den Besselaar Anton M H P, Houdijk Wim P M
Haemostasis and Thrombosis Research Center, Department of Haematology, Leiden University Medical Center, Leiden, The Netherlands.
Clin Chem. 2003 Dec;49(12):2006-11. doi: 10.1373/clinchem.2003.023531.
For monitoring of treatment with oral anticoagulants, the clotting time obtained in the prothrombin time (PT) test is transformed to the International Normalized Ratio (INR) with use of a system-specific International Sensitivity Index (ISI). The calibrant plasma procedure (CPP) is an alternative approach to INR calculation based on the use of a set of lyophilized plasmas with assigned INRs.
With the CPP, a linear relationship is established between log(PT) and log(INR), using orthogonal regression. CPP was validated for Simplastin HTF, a new human tissue factor reagent derived from cultured human cells. CPP precision was assessed as the CV of the slope of the regression line. The accuracy of the CPP was determined by comparing the INR obtained with the CPP with that obtained with the established ISI-based reference method. INRs of the calibrants were assigned by different routes: by manufacturer (consensus labeling) or by use of Simplastin HTF or International Reference Preparations (IRPs; rTF/95 or RBT/90).
The mean CV of the CPP regression slope ranged from 1.0% (Simplastin HTF reagent-specific INR) to 2.4% (INR assigned with rTF/95). INRs calculated with the CPP were similar to those obtained with the reference method, but when the routes for assigning INRs to the calibrant plasmas were compared, the mean difference in INR between CPP and the reference method was smaller with Simplastin HTF reagent-specific values. In several (but not all) cases, this difference was significant (P <0.05, t-test).
CPP can be used for local INR determination, but better precision and accuracy are obtained with reagent-specific INRs compared with INR assignment by consensus labeling or IRP.
对于口服抗凝剂治疗的监测，在凝血酶原时间（PT）测试中获得的凝血时间通过使用特定系统的国际敏感指数（ISI）转换为国际标准化比值（INR）。校准血浆程序（CPP）是一种基于使用一组已指定INR的冻干血浆来计算INR的替代方法。
使用CPP时，通过正交回归在log(PT)和log(INR)之间建立线性关系。CPP已针对Simplastin HTF（一种源自培养人细胞的新型人组织因子试剂）进行了验证。CPP的精密度通过回归线斜率的CV来评估。通过将用CPP获得的INR与用既定的基于ISI的参考方法获得的INR进行比较来确定CPP的准确性。校准物的INR通过不同途径指定：由制造商（共识标记）或通过使用Simplastin HTF或国际参考制剂（IRP；rTF/95或RBT/90）。
CPP回归线斜率的平均CV范围为1.0%（Simplastin HTF试剂特异性INR）至2.4%（用rTF/95指定的INR）。用CPP计算的INR与用参考方法获得的INR相似，但当比较将INR指定给校准血浆的途径时，使用Simplastin HTF试剂特异性值时，CPP和参考方法之间INR的平均差异较小。在一些（但不是所有）情况下，这种差异具有统计学意义（P<0.05，t检验）。
CPP可用于本地INR测定，但与通过共识标记或IRP指定INR相比，使用试剂特异性INR可获得更高的精密度和准确性。
