Russell Viper Venom Time Test Research Articles

Evaluation of the DOAC-Stop Procedure by LC-MS/MS Assays for Determining the Residual Activity of Dabigatran, Rivaroxaban, and Apixaban.

The effect of direct oral anticoagulants (DOACs) on laboratory tests dependent on the production of their targets, factor IIa and factor Xa (FXa), is a well-known problem and can cause both false positive and negative results. Therefore, the correct interpretation of tests performed in patients receiving DOACs is necessary to avoid misclassification and subsequent clinical consequences. However, even with significant experience, there are situations where it is not possible to assess the influence of some methods. Particularly important is the situation in the diagnosis of lupus anticoagulants using the dilute Russell viper venom timetest, which is based on direct FXa activation. A very promising solution to this situation is offered by the DOAC laboratory balancing procedure DOAC-Stop. For evaluating the effectiveness of this procedure, 60 (20 apixaban, 20 dabigatran, and 20 rivaroxaban) patients treated with DOACs were enrolled. All patient samples were analyzed for the presence of individual DOAC types and subsequently subjected to the DOAC-Stop procedure.We evaluated its effectiveness by our own high-performance liquid chromatography-coupled tandem mass spectrometrymethod, which simultaneously sets all high-sensitivity DOACs. Unlike coagulation tests based on the determination of the residual effects of DOACs on target enzymes, which is complicated by extensive interindividual variation, this methodology is highly specific and sensitive.The DOAC-Stop procedure eliminated dabigatran from 99.5%, rivaroxaban from 97.9%, and apixaban from 97.1% of participants in our group. Residual amounts did not exceed 2.7 ng/mL for dabigatran, 10.9 ng/mL for rivaroxaban, or 13.03 ng/mL for apixaban, which are safe values that do not affect either screening or special coagulation tests.

Clinical usefulness of the dilute Russell viper venom time test for patients taking warfarin

Warfarin use often causes false-positive results in the dilute Russell viper venom time test (DRVVT). Thus, three sets of guidelines-those presented by the International Society on Haemostasis and Thrombosis (ISTH), the British Committee for Standards in Haematology (BCSH), and the Clinical and Laboratory Standards Institute (CLSI)-are advocated. We evaluated the clinical usefulness of the testing methods recommended in these three guidelines using laboratory samples. Of the 242 samples from patients using warfarin, 38 were positive for lupus anticoagulant (LA). After adding normal pooled plasma (NPP) as recommended in the ISTH, BCSH, and CLSI guidelines, the number of samples testing positive for LA decreased to 13, 18, and 19, respectively. The number of samples with inconsistent results between the activated partial thromboplastin time and mixing test, and the DRVVT following the ISTH, BCSH, and CLSI guidelines were four of 205 (1.9%), 15 of 242 (6.2%), and 17 of 242 (7.0%), respectively. In patients with an international normalized ratio (INR)≥3.0, 11 of 37 (29.7%) and 12 of 37 (32.4%) samples showed inconsistent results according to the BCSH and CLSI guidelines, respectively. The accuracy of the DRVVT result may thus decrease in markedly anticoagulated patients.

Does the Russell Viper Venom time test provide a rapid estimation of the intensity of oral anticoagulation? A cohort study

BackgroundDilute Russell Viper Venom Time (DRVV-T) might be useful in urgent settings for screening patients on Non-VKA Oral Anticoagulants (NOACs). AimTo compare the accuracy of DRVV-T with gold standard assays for the assessment of pharmacodynamics of dabigatran, rivaroxaban and vitamin K antagonist (VKA) in plasma samples from patients. MethodsSixty rivaroxaban, 48 dabigatran and 50 VKA samples from patients were included. DRVV-T was performed in all groups using STA®-Staclot®DRVV-Screen and -Confirm. For NOACs, PT and aPTT were performed using different reagents while plasma drug concentrations were measured by liquid mass-spectrometry (LC-MS/MS). For VKA, INR was performed using RecombiPlasTin 2G®. ResultsFor NOACs, correlations between calibrated STA®-Staclot®DRVV-Confirm and LC-MS/MS (rs=0.88 and 0.97 for rivaroxaban and dabigatran, respectively) were higher than the ones obtained with STA®-Staclot®DRVV-Screen (rs=0.87 and 0.91), PT (rs=0.83 to 0.86) or aPTT (rs=0.84 to 0.89). Bland Altman analyses showed that calibrated DRVV-T methods tend to overestimate plasma concentrations of NOACs. ROC curves revealed that cut-off to exclude supra-therapeutic levels at Ctrough (i.e. 200ng/mL) are different for dabigatran and rivaroxaban. Neither STA®-Staclot®DRVV-Screen nor –Confirm correlated sufficiently with the intensity of VKA therapy (rs=0.35 and 0.52). ConclusionsSTA®-Staclot®DRVV-Confirm provides a rapid estimation of the intensity of anticoagulation with rivaroxaban or dabigatran without specific calibrators. At Ctrough, thresholds for rivaroxaban and dabigatran can be used to identify supra-therapeutic plasma level. However, this test cannot differentiate the nature of the NOACs. The development of a point-of-care device optimising this method would be of particular interest in emergency situations.

Lupus anticoagulant hypoprothrombinemia syndrome in Bence-Jones protein κ-type multiple myeloma patient with phosphatidylserine-dependent antiprothrombin antibody

Dear Editor, Approximately 2 % of multiple myeloma (MM) patients present with hemorrhage at diagnosis. However, hemorrhage due to abnormalities in the coagulation system is a rare complication [1, 2]. Although lupus anticoagulant (LA), which is infrequently reported to be in association with MM, is commonly a risk factor for arterial or venous thrombosis, bleeding tendencies in patients with LA are strongly related to a low prothrombin activity [3–6]. Acquired hypoprothrombinemia with LA, also called LA hypoprothrombinemia syndrome (LAHPS), is a rare disease which appears mostly in young females with systemic lupus erythematosus or in healthy children after viral infection and is usually associated with the presence of antiprothrombin antibodies [7]. We herein report the case of an 86-year-old male with Bence-Jones protein (BJP) κ-type MM who presented with hypoprothrombinemia and LA associated with antibodies directed to the phosphatidylserine–prothrombin complex (or phosphatidylserine-dependent antiprothrombin antibodies, aPS/PT). The patient was admitted with anemia and had no past history of bleeding disorders or thrombotic events. A urinalysis showed massive proteinuria (5.3 g/day), which was determined to be κ-type BJP using immunoelectrophoresis. Bone marrow aspiration showed proliferation of abnormal plasma cells. Computerized tomography showed hematomas in the bilateral gluteus maximus muscle and the supraclavicular area. Initial coagulation tests showed prolonged prothrombin time and activated partial thromboplastin time (aPTT) (Table 1). Reduced clotting activity of factors II (FII), VIII (FVIII), and IX (FIX) was noted in a pattern typical of that observed in previously reported cases of LAHPS [8, 9]. FVIII and FIX inhibitors were not detected. The prolonged aPTT with LA-sensitive aPTT reagent (PTT-LA Roche Diagnostics, Tokyo, Japan), which could not be corrected by mixing with normal plasma, suggested the presence of LA. The results were confirmed using the Staclot LA® assay, and the dilute Russell viper venom time test was used to confirm the presence of LA with the phospholipid-neutralizing LA test (Gradipore, Frenchs Forest, Australia). IgG/M anticardiolipin antibodies and IgG aPS/PT were negative, while strong positive IgM aPS/PT was detected, which was measured with ELISA using the phosphatidylserine–prothrombin complex as antigen immobilized on ELISA plates in the presence of CaCl2 [10]. Based on these findings, the patient was diagnosed as MM with LAHPS associated with aPS/PT and treated with melphalan and prednisolone (MP) therapy. The FII levels were observed to normalize after one cycle of MP therapy and the patient has remained in remission without any hemorrhage for 10 months. Table 1 Laboratory findings In our case, aPTT continued to be prolonged with reduced levels of FVIII and FIX in spite of normalizing the FII level after therapy. LA and IgM aPS/PT remained positive, although these values were improved, suggesting that the presence of LA might have an influence on coagulation tests after treatment. There are very rare reports showing the presence of aPS/PT in patients with LAHPS [9]. These reports describe the patients as having bleeding tendencies with mildly reduced FII levels, similar to that observed in our patient. However, in previously reported child cases of LAHPS, severe hemorrhage usually occurs when the FII levels are very low (under 10∼15 %). It is possible that other coagulation factors associated with aPS/PT in LAHPS might be present. A diagnosis of LAHPS should always be considered in MM patients with bleeding tendencies associated with LA, and aPS/PT detection should be performed in conjunction with LA tests.

Association of autoantibodies against the phosphatidylserine-prothrombin complex with manifestations of the antiphospholipid syndrome and with the presence of lupus anticoagulant.

To clarify the association of autoantibodies against prothrombin with the clinical manifestations of the antiphospholipid syndrome (APS) and with the presence of lupus anticoagulant (LAC). We examined 265 patients who visited our autoimmune disease clinic. IgG and IgM antiprothrombin antibodies were tested by enzyme-linked immunosorbent assay (ELISA) as either antiphosphatidylserine-prothrombin complex (aPS/PT) antibodies or as antibodies against prothrombin coated on irradiated ELISA plates (as antigen) (aPT). IgG, IgM, and IgA anticardiolipin (aCL) antibodies and their beta2-glycoprotein I (beta2GPI) dependency were also evaluated by ELISA. LAC was tested by 3 different methods. The presence of aPS/PT, but not of aPT, significantly correlated with the clinical manifestations of APS (odds ratio [OR] 4.39, 95% confidence interval [95% CI] 2.06-9.38), and aPS/PT antibodies were as specific as beta2GPI-dependent aCL for APS (93.1% for both). IgG aPS/PT strongly correlated with the presence of LAC as detected using the dilute Russell viper venom time test (OR 38.2, 95% CI 13.4-109.1). Antiprothrombin antibodies are heterogeneous and their clinical relevance depends on the method of detection applied. Positive results on the aPS/PT test can serve as a marker of thrombotic events in patients with autoimmune diseases.

Comparison of an Activated Partial Thromboplastin Time With a Russell Viper Venom Time Test in Screening for Factor VLeiden (FVR506Q)

Factor V(Leiden) is the most common abnormality detected in patients examined because of hereditary thrombophilia. The most widely used clot-based screening test is based on the activated partial thromboplastin (aPTT) time. This test has a low sensitivity. A comparison of the aPTT-based test with a Russell viper venom time test (RVVT) was performed in matched samples. All samples were analyzed by polymerase chain reaction (PCR) for the factor V(Leiden) defect. We studied 139 samples, of which 109 were PCR-negative; 30 were PCR-positive. Using the manufacturer's suggested threshold ratio of 2, the aPTT test showed a sensitivity of 0.43, a specificity of 0.86, and a positive predictive value (PPV) of 0.97. The RVVT test had a sensitivity of 1.0, a specificity of 0.95, and a PPV of 0.91. Segregation of a subpopulation of this study population into ABO group O vs non-group O showed an effect of ABO group on the aPTT test but not on the RVVT test, consistent with an influence of factor VIII clotting (factor VIII:C) on the aPTT test. The RVVT test seems superior to the unmodified aPTT test as a screening test for factor V(Leiden).