Department of Pathology, University of Kansas Medical Center, Kansas City, 66223, USA.
Arch Pathol Lab Med. 2011 Feb;135(2):227-32. doi: 10.5858/135.2.227.
Hereditary and acquired deficiencies of antithrombin (AT), protein C (PC), and protein S (PS) are risk factors for venous thromboembolism. Proper diagnosis requires high-quality assays for these proteins.
To determine the accuracy and interlaboratory precision of AT, PC, and PS assays used by laboratories participating in the United States College of American Pathologists proficiency testing program in thrombophilia and to grade the performance of laboratories.
Standardized normal plasma with assigned analyte values was sent in 2 separate challenges to participating laboratories. Participants measured AT, PC, and PS levels using local methods.
When compared with the assigned values for the international standard, the order of assay accuracy from highest to lowest was AT activity, PC antigen, AT antigen, total PS antigen, PC activity, PS activity, and free PS antigen (range of assay bias, 2.6%-8.8%). The order of assay precision from highest to lowest was PC activity, AT activity, AT antigen, total PS antigen, PS activity, free PS antigen, and PC antigen (range of assay coefficient of variation, 6.1%-20.0%). Most testing events (87.8%) could be graded as pass or fail using a target range of ±3 standard deviations from the method-specific mean. The pass rate was 98.2% for all AT, PC, and PS testing events combined.
Accuracy and precision were higher for AT assays and lower for PC and PS assays. It was feasible to grade individual laboratory performance.
抗凝血酶（AT）、蛋白 C（PC）和蛋白 S（PS）的遗传性和获得性缺乏是静脉血栓栓塞的危险因素。正确的诊断需要对这些蛋白质进行高质量的检测。
确定参加美国病理学家学院血栓形成症能力验证计划的实验室使用的 AT、PC 和 PS 检测的准确性和实验室间精密度，并对实验室的性能进行分级。
用 2 种单独的方法将具有指定分析物值的标准化正常血浆发送给参与实验室。参与者使用当地方法测量 AT、PC 和 PS 水平。
与国际标准的赋值相比，检测准确性的顺序从高到低依次为 AT 活性、PC 抗原、AT 抗原、总 PS 抗原、PC 活性、PS 活性和游离 PS 抗原（检测偏倚范围为 2.6%8.8%）。检测精度的顺序从高到低依次为 PC 活性、AT 活性、AT 抗原、总 PS 抗原、PS 活性、游离 PS 抗原和 PC 抗原（检测变异系数范围为 6.1%20.0%）。使用方法特异性平均值 ±3 个标准差的目标范围，大多数检测事件（87.8%）可被评为通过或失败。所有 AT、PC 和 PS 检测事件的通过率为 98.2%。
AT 检测的准确性和精密度较高，而 PC 和 PS 检测的准确性和精密度较低。对单个实验室的性能进行分级是可行的。
