Martinuzzo M E, Barrera L H, D 'adamo M A, Otaso J C, Gimenez M I, Oyhamburu J
Grupo Bioquímico, Laboratorio Central, Hospital Italiano de Buenos Aires, CABA, Argentina.
Int J Lab Hematol. 2014 Apr;36(2):144-50. doi: 10.1111/ijlh.12138. Epub 2013 Sep 6.
Oral direct thrombin and Xa inhibitors are worldwide distributed for prevention and treatment of thrombosis. It is important to recognize their effects on lupus anticoagulant (LA) testing. The aim of the study is to describe the rate of false-positive results of LA tests on plasmas of patients with previous negative LA tests results that receive dabigatran etexilate (DAB) 110 mg/twice a day, rivaroxaban (RIV) 10 mg/day or 15 mg/twice a day, or enoxaparin 40 mg/day.
Blood was taken between 1.5 and 4 h post administration. Tests evaluated are as follows: prothrombin time, APTT, dilute Russell viper venom time (DRVVT) screen, APTT, and DRVVT mixing studies, index of circulating anticoagulant (ICA) with normal plasma, screen/confirm normalized ratio (NR) for DRVVT and silica clotting time (SCT).
Plasmas from patients taking DAB (n = 22) presented 100% prolonged APTT and DRVVT with ICA above the cutoff point and 81.8% positive screen/confirm NR, 100% prolonged SCT screen, but 4.5% positive confirmatory NR. All patients receiving RIV at 15 mg/twice a day (n = 4) presented positive DRVVT screen, mixing, and confirmatory tests, 75% and 100% prolonged APTT and SCT screen, with negative screen/confirm NR. Those taking RIV 10 mg/day (n = 22) showed 81.8% prolonged DRVVT screen, 82.3% and 76.5% of them with positive mixing and confirmatory studies. Patients receiving enoxaparin also presented high prevalence of APTT and DRVVT false-positive results.
Dabigatran etexilate, RIV, and enoxaparin affect tests for LA not only in screening and mixing, but also in confirmatory studies. We considered that LA testing should not to be performed when patients are taken these drugs, particularly if blood is collected at peak, in order to avoid false-positive results.
口服直接凝血酶抑制剂和Xa因子抑制剂在全球范围内用于血栓形成的预防和治疗。认识到它们对狼疮抗凝物（LA）检测的影响很重要。本研究的目的是描述接受达比加群酯（DAB）110mg/每日两次、利伐沙班（RIV）10mg/每日或15mg/每日两次或依诺肝素40mg/每日的LA检测结果先前为阴性的患者血浆中LA检测假阳性结果的发生率。
在给药后1.5至4小时之间采集血液。评估的检测项目如下：凝血酶原时间、活化部分凝血活酶时间（APTT）、稀释蝰蛇毒时间（DRVVT）筛查、APTT以及DRVVT混合试验；与正常血浆的循环抗凝物指数（ICA）、DRVVT的筛查/确认标准化比值（NR）以及硅土凝血时间（SCT）。
服用DAB的患者（n = 22）的血浆显示APTT和DRVVT均100%延长，ICA高于临界值，筛查/确认NR的阳性率为81.8%，SCT筛查100%延长，但确认性NR的阳性率为4.5%。所有接受每日两次15mg RIV治疗的患者（n = 4）DRVVT筛查、混合试验及确认性试验均呈阳性，APTT和SCT筛查分别有75%和100%延长，筛查/确认NR为阴性。那些服用每日10mg RIV的患者（n = 22）显示DRVVT筛查延长的比例为81.8%，其中82.3%和76.5%的患者混合试验和确认性试验呈阳性。接受依诺肝素治疗的患者APTT和DRVVT假阳性结果的发生率也很高。
达比加群酯、利伐沙班和依诺肝素不仅在筛查和混合试验中，而且在确认性试验中都会影响LA检测。我们认为，当患者服用这些药物时，尤其是在血药浓度峰值时采血，不应进行LA检测，以避免出现假阳性结果。
