Survey of lupus anticoagulant diagnosis by central evaluation of positive plasma samples
Survey of lupus anticoagulant diagnosis by central evaluation of positive plasma samples
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DOI：
10.1111/j.1538-7836.2007.02454.x
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发表时间：
2007-05-01
影响因子：
10.4
通讯作者：
Tripodi, A.
中科院分区：
文献类型：
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作者：
Pengo, V.;Biasiolo, A.;Tripodi, A.
目的：确定是否在参考实验室确认了大型阳性患者队列中狼疮抗凝剂（LAC）的诊断。方法：在1年的时间内，每个参与中心从LAC阳性患者中收集样本。过滤血浆并深度冷冻，直到用干冰通过快递运送到参考实验室。中心返回了每例患者的详细实验室信息和临床数据。参考实验室通过稀释罗素蝰蛇毒时间（dRVVT）和高岭土凝血时间（KCT）筛选血浆样本。当这些时间延长时，进行1：1混合研究，并酌情进行确证性试验。阳性标本进一步检测凝血酶时间（TT）。当TT延长时，通过测量抗Xa因子活性来检查肝素的存在。使用六方磷脂通过活化部分凝血活酶时间检测阴性样本。结果：分析了来自29个抗凝诊所的302例患者的血浆样本。在71份样本（24%）中排除了LAC，因为dRVVT和KCT筛选试验结果正常（34）或通过混合研究逆转为正常（35）。其余两份样本被认为是阴性的，因为它们含有肝素。LAC阴性患者表现出与确诊患者不同的特征。他们明显年龄较大（49.7 vs. 45.0岁，P < 0.03），首次诊断的频率更高（66% vs. 41%，P < 0.001），LAC效价更常被判定为轻度（60% vs. 25%，P < 0.0001）。此外，LAC阴性样本中抗心磷脂和抗β 2-糖蛋白I抗体值正常的比例（82%）高于LAC阳性样本（42%）（P < 0.0001）。通过dRVVT和KCT鉴别的LAC阳性样本（146/231，63%）显示的LAC效价显著强于通过单一检测进行LAC诊断的样本。结论：假阳性LAC诊断在专业中心并不少见。患者的特征和完整的抗磷脂抗体谱可能有助于识别这些个体。
Objective: To determine whether the diagnosis of lupus anticoagulant (LAC) in a large cohort of positive patients was confirmed at a reference laboratory. Methods: Over a 1-year period, each participating center collected samples from LAC-positive patients. Plasma was filtered and kept deep-frozen until it was sent on dry ice to the reference laboratory by express courier. Centers returned detailed laboratory information and clinical data from each patient. The reference laboratory screened plasma samples by diluted Russell viper venom time (dRVVT) and kaolin clotting time (KCT). When these were prolonged, 1:1 mixing studies were carried out, and confirmatory tests were performed as appropriate. Positive samples were further tested by thrombin time (TT). The presence of heparin was checked by measuring antifactor Xa activity when TT was prolonged. Negative samples were tested by activated partial thromboplastin time using hexagonal phospholipids. Results: Plasma samples from 302 patients from 29 anticoagulation clinics were analyzed. LAC was excluded in 71 samples (24%), because dRVVT and KCT screening test results were normal (34) or reversed to normal by mixing studies (35). The remaining two samples were considered negative because they contained heparin. LAC-negative patients showed different characteristics from those in whom diagnosis was confirmed. They were significantly older (49.7 vs. 45.0 years, P < 0.03), were more often first diagnosed (66% vs. 41%, P < 0.001), and were more frequently judged as mild in LAC potency (60% vs. 25%, P < 0.0001). Moreover, anticardiolipin and anti-beta(2)-glycoprotein I antibody values were more often normal in LAC-negative (82%) than in LAC-positive (42%) samples (P < 0.0001). LAC-positive samples identified by both dRVVT and KCT (146/231, 63%) showed a LAC potency that was significantly stronger than that in samples in which LAC diagnosis was made by a single test. Conclusions: A false-positive LAC diagnosis is not uncommon across specialized centers. Patients' characteristics and a complete antiphospholipid antibody profile may help to identify these individuals.