Schmidt David E, Holmström Margareta, Majeed Ammar, Näslin Doris, Wallén Håkan, Ågren Anna
Department of Medicine, Division of Hematology, Coagulation Unit, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden; Utrecht University Medical Center, Utrecht, The Netherlands.
Department of Medicine, Division of Hematology, Coagulation Unit, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden.
Thromb Res. 2015 May;135(5):1007-11. doi: 10.1016/j.thromres.2015.02.022. Epub 2015 Feb 26.
The diagnostic potential of whole blood viscoelastic tests thromboelastography (TEG®) and thromboelastometry (ROTEM®) to detect warfarin-induced INR elevation remains elusive.
Viscoelastic tests were performed in 107 patients on warfarin and 89 healthy controls. Tests were activated by kaolin for TEG, and ellagic acid (INTEM) or tissue factor (EXTEM) for ROTEM.
Viscoelastic tests revealed significant differences in clotting profiles between controls and warfarin-treated patients. Compared with healthy controls, patients treated with warfarin had prolonged EXTEM clotting and TEG reaction time (p<0.001), both of which were also increased beyond the reference range. Increased INR values correlated with EXTEM CT (Spearman rho=0.87) and TEG R-time (rho=0.73). EXTEM CT had a sensitivity and specificity of 0.89 and 1.00, respectively, to detect elevated INR above 1.2 units, with a positive and negative predictive values (PPV and NPV) of 1.00 and 0.88, respectively. Similarly, TEG R-time had a sensitivity and specificity of 0.86 and 0.87, respectively, with a PPV of 0.89 and a NPV of 0.83. The corresponding receiver operator characteristic area under the curve was 0.99 (95% confidence interval [CI], 0.99 - 1.00) for EXTEM CT and 0.94 (95% CI, 0.91 - 0.97) for TEG R-time.
Tissue factor-activated viscoelastic testing (EXTEM) revealed individuals with warfarin-induced INR elevation accurately, while TEG - activated through the intrinsic pathway - still was of acceptable diagnostic value. Further studies are required to evaluate the diagnostic potential of viscoelastic tests in relation to standard laboratory tests in other mixed patient populations, where the PPV and NPV may be inferior.
全血粘弹性检测血栓弹力图（TEG®）和血栓弹性测定法（ROTEM®）在检测华法林引起的国际标准化比值（INR）升高方面的诊断潜力仍不明确。
对107例服用华法林的患者和89名健康对照者进行粘弹性检测。TEG检测通过高岭土激活，ROTEM检测通过鞣花酸（INTEM）或组织因子（EXTEM）激活。
粘弹性检测显示，对照组与接受华法林治疗的患者之间的凝血曲线存在显著差异。与健康对照者相比，接受华法林治疗的患者EXTEM凝血时间和TEG反应时间延长（p<0.001），两者均超出参考范围。INR值升高与EXTEM凝血时间（Spearman相关系数rho=0.87）和TEG反应时间（rho=0.73）相关。EXTEM凝血时间检测INR高于1.2单位时的敏感性和特异性分别为0.89和1.00，阳性预测值和阴性预测值（PPV和NPV）分别为1.00和0.88。同样，TEG反应时间的敏感性和特异性分别为0.86和0.87，PPV为0.89，NPV为0.83。EXTEM凝血时间的相应曲线下面积为0.99（95%置信区间[CI]，0.99 - 1.00），TEG反应时间为0.94（95%CI，0.91 - 0.97）。
组织因子激活的粘弹性检测（EXTEM）能准确检测出华法林引起的INR升高的个体，而通过内源性途径激活的TEG仍具有可接受的诊断价值。需要进一步研究评估粘弹性检测在其他混合患者群体中相对于标准实验室检测的诊断潜力，在这些群体中PPV和NPV可能较低。
