Chen Jian, Phillips Bonnie, Chandler Wayne L
aDepartment of Pathology, College of Medicine, The Ohio State University, Columbus, Ohio bDepartment of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, Texas cDepartment of Laboratories, Seattle Children's Hospital, Seattle, Washington, USA.
Blood Coagul Fibrinolysis. 2016 Jan;27(1):90-6. doi: 10.1097/MBC.0000000000000375.
Mixing studies for prolonged prothrombin time (PT)/activated partial thromboplastin time (aPTT) are used to estimate whether the prolongation is due to an inhibitor or factor deficiency. We propose a new method of mixing study interpretation based on estimation of average factor level changes. Factor level vs. PT/aPTT curves were prepared for single factor, vitamin K-dependent factor, and all factor deficiencies. These curves were used to predict the factor level in the sample and the correction needed to differentiate deficiencies from inhibitors. We compared this estimated factor correction (EFC) method to normal range, percentage correction, and Rosner index. For a given factor level, multiple factor deficiencies prolonged the PT/aPTT more than single factor deficiency, necessitating different thresholds for defining correction on mixing studies. The EFC method was superior to other the correction methods, correctly identifying 38 of 39 known inhibitors, single and multiple factor deficiencies, and correctly identifying inhibitor vs. deficiency in 50 of 59 patient samples. In 99 adult patient mixing studies over 18 months, 30% showed deficiency only, 30% inhibitor only, whereas 40% showed evidence of both. The EFC method for PT/aPTT mixing study interpretation was more accurate than the comparison methods at determining deficiency versus inhibitor.
延长凝血酶原时间（PT）/活化部分凝血活酶时间（aPTT）的混合试验用于评估延长是由抑制剂还是因子缺乏引起的。我们基于平均因子水平变化的估计提出了一种新的混合试验解释方法。针对单一因子、维生素K依赖因子和所有因子缺乏情况绘制了因子水平与PT/aPTT曲线。这些曲线用于预测样本中的因子水平以及区分缺乏与抑制剂所需的校正值。我们将这种估计因子校正（EFC）方法与正常范围、百分比校正和罗斯纳指数进行了比较。对于给定的因子水平，多种因子缺乏比单一因子缺乏更能延长PT/aPTT，因此在混合试验中定义校正时有必要采用不同的阈值。EFC方法优于其他校正方法，在39个已知抑制剂、单一和多种因子缺乏情况中正确识别出38个，在59个患者样本中的50个中正确识别出抑制剂与缺乏情况。在18个月内对99例成年患者进行的混合试验中，30%仅显示缺乏，30%仅显示抑制剂，而40%显示两者都有证据。在确定缺乏与抑制剂方面，用于PT/aPTT混合试验解释的EFC方法比比较方法更准确。
