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Tang N, Xiang Y, Li D. The features of patients with lupus anticoagulant result presenting as negative screen test and positive normalized ratio. Thromb Res 2022; 216:103-105. [PMID: 35780531 DOI: 10.1016/j.thromres.2022.06.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 06/22/2022] [Accepted: 06/27/2022] [Indexed: 11/27/2022]
Affiliation(s)
- Ning Tang
- Clinical Laboratory, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
| | - Yueyun Xiang
- Clinical Laboratory, Hunan Provincial Maternal and Child Health Care Hospital, Changsha, China
| | - Dengju Li
- Hematology Department, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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Ling LQ, Liu CN, Huang XB, Liao J, Jia J, Zhou J. Interpretation of clot-based lupus anticoagulant assays-Normalizing clotting time against different denominators. Int J Lab Hematol 2022; 44:777-784. [PMID: 35297205 DOI: 10.1111/ijlh.13830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 02/24/2022] [Accepted: 03/02/2022] [Indexed: 02/05/2023]
Abstract
OBJECTIVES The endpoint for all lupus anticoagulant (LA) assays is a clotting time in seconds. This study aimed to clarify the use of normalizing clotting time to ratio and how the use of different denominators is relevant. METHODS Whether normalization could reduce reagent variability and possess better diagnostic performances was assessed; denominators included reference interval (RI) mean, local-obtained pooled plasma clotting time, standard plasma clotting time, and control plasma clotting time (CNPPct). Moreover, whether day-to-day variation in CNPPct would impact its application was studied. RESULTS If not normalized, significant difference existed among different reagent batches; if normalized (against any denominators), no statistically significant difference existed anymore. The validation of in-house RIs achieved a 100% success rate. Normalization against different denominators had different RIs, but the same diagnostic efficacies (when a prolonged LA1 is used to suggest further LA-related testings, normalized LA1 demonstrated a better sensitivity: 1.0 vs. 0.95). Normalization against a "daily" CNPPct (obtained alongside test plasmas day to day) demonstrated low inter-day variations (LA1: ~1%, LA2: ~1%), and it could employ the RI for normalization against a "fixed" CNPPct (obtained alongside normal plasmas when the RI was established). CONCLUSIONS Normalizing clotting time reduces reagent-batch variability and promotes the adoption of common RIs, and therefore reduces the necessity of establishing RI for new reagent batches. Normalized LA1 is more sensitive when used to suggest further LA-related testings, and therefore reduces the rate of missed LA diagnosis. All denominators are of the same application value. Day-to-day variation in CNPPct did not impact its application as a reliable denominator.
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Affiliation(s)
- Li-Qin Ling
- Department of Laboratory Medicine, West China Hospital, Sichuan University, Chengdu, China
| | - Chao-Nan Liu
- Department of Laboratory Medicine, West China Hospital, Sichuan University, Chengdu, China
| | - Xun-Bei Huang
- Department of Laboratory Medicine, West China Hospital, Sichuan University, Chengdu, China
| | - Juan Liao
- Department of Laboratory Medicine, West China Hospital, Sichuan University, Chengdu, China
| | - Jin Jia
- Department of Laboratory Medicine, West China Hospital, Sichuan University, Chengdu, China
| | - Jing Zhou
- Department of Laboratory Medicine, West China Hospital, Sichuan University, Chengdu, China
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Asakrah S, Davis R, Bhargava P. Practical Considerations and Testing Nuances for the Detection of Lupus Anticoagulant: Do Low Phospholipid Screen Results, Assay Type, and Test Ratio Matter? Am J Clin Pathol 2021; 156:1073-1082. [PMID: 34075395 DOI: 10.1093/ajcp/aqab069] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVES Lupus anticoagulant (LA) detection requires (1) prolongation of a phospholipid (PL)-dependent clot-based screening assay, (2) noncorrection upon adding normal pooled plasma, and (3) a confirmatory PL dependency test. Paired LA assays run screening and confirmatory tests simultaneously, with their test ratio (TR) or differences used to evaluate test results. We evaluated patients whose paired testing demonstrated PL dependence suggestive of LA, yet the low PL screen was not prolonged. METHODS Clinical and laboratory parameters are compared across (1) true positive (screen prolonged, TR positive) vs borderline (screen not prolonged, TR positive); (2) low-, moderate-, and high-TR subgroups; and (3) dilute Russell viper venom time (dRVVT) vs silica clotting time (SCT). RESULTS Borderline samples are not statistically different from true positives in their rate of repeat LA positivity or association with other anti-PL antibodies. Compared with true positives, borderline dRVVT is more frequent in pregnancy, women, and younger age. Elevated activated partial thromboplastin time is more frequent in true-positive dRVVT and SCT vs borderline and with an increasing dRVVT TR. LA persistence is more frequent with an increasing SCT TR. In addition, dRVVT true positivity is more frequent with thromboembolic events, while SCT is more frequent with autoimmunity and pregnancy complications. CONCLUSIONS Negative low-PL screens may not necessarily lack LA. A reevaluation of the laboratory criteria for LA detection may be needed.
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Affiliation(s)
- Saja Asakrah
- Department of Pathology and Laboratory Medicine, Emory University, Atlanta, GA,USA
| | - Roger Davis
- Beth Israel Deaconess Medical Center, Boston, MA, USA
| | - Parul Bhargava
- Department of Pathology and Laboratory Medicine, University of California, San Francisco, San Francisco, CA, USA
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Baker SA, Jin J, Pfaffroth C, Vu T, Zehnder JL. DOAC-Stop in lupus anticoagulant testing: Direct oral anticoagulant interference removed in most samples. Res Pract Thromb Haemost 2021; 5:314-325. [PMID: 33733031 PMCID: PMC7938630 DOI: 10.1002/rth2.12472] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2020] [Revised: 11/14/2020] [Accepted: 11/20/2020] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND The use of direct oral anticoagulants (DOACs) is a convenient therapeutic option for patients at risk of thrombosis. DOACs interfere with clot-based testing for the identification of lupus anticoagulant antibodies (LACs) in patients with antiphospholipid syndrome (APS), a common cause of acquired thrombotic disease. OBJECTIVES To evaluate a commercially available reagent DOAC-Stop for the removal of DOAC interference encountered in LAC testing. PATIENTS/METHODS We collected a cohort of 73 test samples from patients on DOAC therapy identified at a large institutional coagulation laboratory from March to December 2019, along with samples from 40 LAC positive and negative control patients not on therapy. Samples were treated with DOAC-Stop and tested for anti-Xa activity and thrombin time for the removal of apixaban, rivaroxaban, argatroban, and dabigatran activity from patient samples. Treated and untreated samples were tested using the activated partial thromboplastin time, silica clotting time, and dilute Russell's viper venom time to evaluate the reliability and utility of DOAC-Stop. RESULTS DOAC-Stop markedly reduced DOAC interference from test samples (P < .05). DOAC-Stop had no effect on LAC testing in the absence of DOAC therapy, permitting the identification of all LAC positive and negative controls. DOAC-Stop removed false positives and false negatives resulting from DOAC interference and allows the identification of patients meeting criteria for the diagnosis of APS by LAC testing, as well as the detection of patients on rivaroxaban who are triple positive for APS. CONCLUSIONS DOAC-Stop is an effective adjunct for the clinical laboratory faced with DOAC interference in LAC testing.
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Affiliation(s)
| | - Jing Jin
- Department of Special Coagulation Clinical LaboratoryStanford Health CarePalo AltoCAUSA
| | - Christopher Pfaffroth
- Department of Special Coagulation Clinical LaboratoryStanford Health CarePalo AltoCAUSA
| | - Trang Vu
- Department of Special Coagulation Clinical LaboratoryStanford Health CarePalo AltoCAUSA
| | - James L. Zehnder
- Department of PathologyStanford University School of MedicineStanfordCAUSA
- Division of HematologyStanford University School of MedicineStanfordCAUSA
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Tripodi A, Cohen H, Devreese KMJ. Lupus anticoagulant detection in anticoagulated patients. Guidance from the Scientific and Standardization Committee for lupus anticoagulant/antiphospholipid antibodies of the International Society on Thrombosis and Haemostasis. J Thromb Haemost 2020; 18:1569-1575. [PMID: 32619349 DOI: 10.1111/jth.14846] [Citation(s) in RCA: 72] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 03/16/2020] [Accepted: 04/10/2020] [Indexed: 12/22/2022]
Abstract
BACKGROUND The laboratory detection of lupus anticoagulants (LA) in anticoagulated patients represents a challenge and there is no consensus on the types of assays/procedures to be adopted. OBJECTIVES This communication of the International Society on Thrombosis and Haemostasis (ISTH), Scientific and Standardization Committee (SSC) aims to give guidance on the procedures to be adopted. METHODS Members of the ISTH-SSC on Lupus Anticoagulant/Antiphospholipid Antibodies reviewed the literature to search for evidence on the most appropriate assays/procedures to be adopted. RESULTS Anticoagulants are able to interfere with the tests used for LA detection, giving rise to occasional false-positive or false-negative LA. Some commercial tests include in their composition heparin-neutralizers able to quench unfractionated or low molecular weight heparin up to 1.0 U/mL. LA tests are less affected by low molecular weight heparin, but caution is needed in the interpretation of results. Vitamin K antagonists (VKAs) may affect LA detection. Dilution of test plasma into pooled normal plasma is not a reliable solution as false-negative or false-positive LA may occur. Direct oral anticoagulants (DOACs) affect LA detection. Hence, it is not recommended to attempt LA detection in those patients. The use of DOAC adsorbents is a promising solution and should be further investigated on LA-positive and LA-negative patient populations. Taipan/Ecarin tests may be a solution for VKAs and anti-FXa DOACs, but independent evidence on their value and standardized kits is needed. CONCLUSIONS LA detection during anticoagulation remains a challenge, especially for VKAs. DOAC removal by in vitro addition to plasma of appropriate absorbents is promising.
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Affiliation(s)
- Armando Tripodi
- Foundation IRCCS Ca' Granda Ospedale Maggiore Policlinico, Angelo Bianchi Bonomi Hemophilia and Thrombosis Center and Fondazione Luigi Villa, Milano, Italy
| | - Hannah Cohen
- Haemostasis Research Unit, Department of Haematology, University College London, London, UK
- Department of Haematology, University College London Hospitals NHS Foundation Trust, London, UK
| | - Katrien M J Devreese
- Coagulation Laboratory, Department of Diagnostic Sciences, Ghent University Hospital, Ghent, Belgium
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Moore GW, Kumano O. Lupus anticoagulant assay cut-offs vary between reagents even when derived from a common set of normal donor plasmas. J Thromb Haemost 2020; 18:439-444. [PMID: 31663664 DOI: 10.1111/jth.14669] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 10/20/2019] [Indexed: 12/12/2022]
Abstract
BACKGROUND Multicenter studies reveal that diagnostic efficacy of lupus anticoagulant (LA) assays is enhanced if cut-offs are locally generated. However, a potential confounder is the inevitable use of separate normal donor populations. OBJECTIVES Generate cut-offs for multiple LA reagents with the same analyzer and normal donor plasmas. METHODS Cut-offs for screen ratio, confirm ratio, percent correction of screen ratio by confirm ratio, and normalized screen/confirm ratio (NSCR) were derived from the same 50 normal donor plasmas for screen and confirm pairs for two dilute Russell's viper venom time reagents, LA1/LA2 and HEMOCLOT™ LA-S/LA-C, and two APTTs, Actin FSL/FS and Cephen LS/Cephen. The cut-offs were challenged with plasmas from 20 triple-positive APS patients and 25 plasmas from LA-negative, thrombotic patients. RESULTS Cut-offs for screen ratio, confirm ratio, percent correction, and NSCR, respectively, were 1.12/1.08/8.3/1.09 for LA1/LA2; 1.17/1.10/13.6/1.13 for HEMOCLOT™ LA-S/LA-C; 1.12/1.13/9.7/1.10 for Actin FSL/FS; 1.09/1.13/11.0/1.11 for Cephen LS/Cephen. LA1 and LA-S screens were elevated in 19/20 and 16/20 triple-positive plasmas, respectively, while 20/20 were detected with both via integrated interpretation ie, percent correction or NSCR irrespective of screen elevation. Actin FSL and Cephen LS screens were elevated in 17/20 and 19/20 triple-positive plasmas, respectively, while one more LA was detected with Actin FSL via integrated interpretation, but not for Cephen LS. Integrated interpretation suggested 5/25 LA-negative plasmas contained weak LA (two with Actin FSL/FS, two with LA1/LA2, one with LA-S/LA-R). CONCLUSIONS Employing the same normal donor plasmas and analytical platform does not compensate for between-reagent differences when generating LA assay cut-offs.
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Affiliation(s)
- Gary W Moore
- Department of Haemostasis and Thrombosis, Viapath Analytics, Guy's & St. Thomas' Hospitals, London, UK
| | - Osamu Kumano
- Protein Technology, Sysmex Corporation, Kobe, Japan
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Kumano O, Moore GW. Ruling out lupus anticoagulants with mixing test-specific cutoff assessment and the index of circulating anticoagulant. Res Pract Thromb Haemost 2019; 3:695-703. [PMID: 31624789 PMCID: PMC6781930 DOI: 10.1002/rth2.12245] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 06/18/2019] [Accepted: 06/27/2019] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND Lupus anticoagulant (LA) is classified in the antibody family that is recognized in antiphospholipid syndrome. Mixing tests are recommended for LA detection, and either a mixing test-specific cutoff (MTC) or index of circulating anticoagulant (ICA) is used for the interpretation. Although we previously showed MTC had higher sensitivity for LA than ICA, there are few studies investigating specificity. OBJECTIVES To investigate specificity of multiple activated partial thromboplastin time (APTT) and diluted Russell's viper venom time (dRVVT) reagents for inhibitors using plasmas with non-LA causes of prolonged clotting times, interpreted with MTC and ICA. METHODS Seventy-six factor-deficient samples (either artificially prepared, hereditary deficiency, or warfarin), and 12 inhibitors (either coagulation factor inhibitors, rivaroxaban, or apixaban) were used. Samples were tested with 4 APTTs, 1 dilute APTT (dAPTT), and 2 dRVVT reagents, and all elevated screen ratios were followed up with mixing tests. Frequencies of corrected and not-corrected results were calculated. RESULTS The frequency of MTC and ICA corrected results, suggesting factor deficiency, were 5% to 43% and 79% to 100%, respectively, except for dAPTT, where MTC and ICA performed similarly. Frequencies of MTC and ICA not-corrected results, suggesting inhibition, were 29% to 100% and 25% to 67%, respectively. CONCLUSIONS The data indicate that MTC has a tendency to generate not-corrected mixing tests in factor-deficient, warfarin, and other inhibitor samples, while ICA exhibited higher specificity. When we perform the mixing test and interpret the data, it is important to understand the characteristics of the indexes for maximizing the diagnostic potential of mixing test.
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Affiliation(s)
- Osamu Kumano
- Protein TechnologySysmex CorporationKobeHyogoJapan
| | - Gary W. Moore
- Department of Haemostasis and ThrombosisViapath AnalyticsGuy's & St. Thomas’ HospitalsLondonUK
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Biguzzi E, Asti D, Palmucci C, Tripodi A, Chantarangkul V. Laboratory diagnostic outcome applying detection criteria recommended by the Scientific and Standardization Committee of the ISTH on Lupus Anticoagulant. Thromb Haemost 2017; 110:46-52. [DOI: 10.1160/th12-11-0850] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Accepted: 04/10/2013] [Indexed: 11/05/2022]
Abstract
SummaryThis study shows the diagnostic outcome of an APTT-based and two dRVVT-based commercial confirmatory integrated tests with the application of the recommendations by the Scientific and Standardization Committee (SSC) on Lupus anticoagulant (LA)/antiphospholipid syndrome (APS) of the International Society on Thrombosis and Haemostasis (ISTH) issued in 2009 concerning the cut-off values for the screening, mixing and confirmatory tests for the detection of LA and the mandatory need to perform mixing tests of patient plasma with pooled normal plasma. The study population included 565 patients collected from a large central coagulation laboratory, for which the attending physicians requested LA detection. One-hundred-six healthy subjects (HS) and 131 selected patients on oral anticoagulant therapy (OAT) were included as negative controls. The results suggest that the performance of mixing tests is indicated for those methods with relatively poor specificity, but is less needed for those methods with high specificity. Furthermore, the SSC recommendation to use normal mid-value (i.e. the 50th percentile of distribution of results from healthy subjects) as the cut-off to interpret results of confirmatory tests, showed a modest increase in LA detection rate (sensitivity) but at the expense of specificity, particularly in methods with low specificity.
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Moore GW. Current Controversies in Lupus Anticoagulant Detection. Antibodies (Basel) 2016; 5:E22. [PMID: 31558003 PMCID: PMC6698846 DOI: 10.3390/antib5040022] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 11/17/2016] [Accepted: 11/18/2016] [Indexed: 01/19/2023] Open
Abstract
Antiphospholipid syndrome is an autoimmune, acquired thrombophilia diagnosed when vascular thrombosis or pregnancy morbidity are accompanied by persistent antiphospholipid antibodies. Lupus anticoagulants (LA) are one of the criteria antibodies but calibration plasmas are unavailable and they are detected by inference based on antibody behaviour in a medley of coagulation-based assays. Elevated screening tests suggest the presence of a LA, which is confirmed with mixing tests to evidence inhibition and confirmatory tests to demonstrate phospholipid-dependence. At least two screening tests of different principle must be used to account for antibody heterogeneity and controversy exists on whether assays, in addition to dilute Russell's viper venom time and activated partial thromboplastin time, should be employed. A variety of approaches to raw data manipulation and interpretation attract debate, as does inclusion or exclusion of mixing studies in circumstances where the presence of a LA is already evident from other results. Therapeutic anticoagulation compromises coagulation-based assays but careful data interpretation and use of alternative reagents can detect or exclude LA in specific circumstances, and this aspect of LA detection continues to evolve. This review focuses on the main areas of debate in LA detection.
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Affiliation(s)
- Gary W Moore
- Diagnostic Haemostasis & Thrombosis Laboratories, Department of Haemostasis and Thrombosis, Viapath Analytics, Guy's & St. Thomas' NHS Foundation Hospitals Trust, 4th floor North Wing, St. Thomas' Hospital, Westminster Bridge Road, London SE1 7EH, UK.
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Moore GW, Brown KL, Bromidge ES, Drew AJ, Ledford-Kraemer MR. Lupus anticoagulant detection: out of control? Int J Lab Hematol 2012; 35:128-36. [DOI: 10.1111/ijlh.12006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Accepted: 08/08/2012] [Indexed: 01/05/2023]
Affiliation(s)
- G. W. Moore
- Department of Haemostasis and Thrombosis; GSTS Pathology; Guy's & St. Thomas' Hospitals; London; UK
| | - K. L. Brown
- Department of Haemostasis and Thrombosis; GSTS Pathology; Guy's & St. Thomas' Hospitals; London; UK
| | - E. S. Bromidge
- Department of Haemostasis and Thrombosis; GSTS Pathology; Guy's & St. Thomas' Hospitals; London; UK
| | - A. J. Drew
- Department of Haemostasis and Thrombosis; GSTS Pathology; Guy's & St. Thomas' Hospitals; London; UK
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Abstract
The laboratory criteria of the antiphospholipid syndrome include one coagulation assay (lupus anticoagulant [LA]) and two solid phase assays (anticardiolipin [aCL] and anti-ß2glycoprotein I antibodies [aß2GPI]). External quality control (EQC) surveys show that negative and clearly positive LA samples are classified correctly by about 95% of laboratories. For ‘weak’ LA there is a wide variability in samples’ classification. Furthermore, when a weak LA sample is used in two different EQC surveys more than 50% of laboratories classify it differently. In some surveys weak LA samples were found to be positive for aCL and for aß2GPI by a majority of laboratories; the main reason for laboratories which classified these samples as LA negative was a negative result in the mixing test. It is likely that, depending on the sensitivity of the assay, a weak LA cannot be detected anymore after 1:1 dilution of the sample with normal plasma. Therefore, we recommend the use of integrated assays, such as screen/confirm ratios, for the detection of weak LA samples.
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Affiliation(s)
- G Reber
- Genetics and Laboratory Medicine Department, Geneva University Hospital and Faculty of Medicine, University of Geneva, Switzerland
| | - P Meijer
- The External quality Control for Assays and Tests (ECAT) Foundation, Leiden, The Netherlands
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Kovacs MJ, Louzada M, Lazo-Langner A. More on: lupus anticoagulant testing during acute thrombotic events. J Thromb Haemost 2011; 9:1682-3. [PMID: 21645229 DOI: 10.1111/j.1538-7836.2011.04379.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Devreese KMJ. No more mixing tests required for integrated assay systems in the laboratory diagnosis of lupus anticoagulants? J Thromb Haemost 2010; 8:1120-2. [PMID: 20149080 DOI: 10.1111/j.1538-7836.2010.03807.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Abstract
Lupus anticoagulants (LA) are acquired autoantibodies that can cause antiphospholipid syndrome. LAs prolong phospholipid-dependent coagulation tests, acting as nonspecific inhibitors that are neutralized in the presence of excess phospholipid. However, there is no gold standard test and the testing is influenced by a number of variables. This article summarizes laboratory testing for LAs, with particular focus on technical issues and limitations of testing. Am. J. Hematol. 2009. (c) 2009 Wiley-Liss, Inc.
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Affiliation(s)
- Kristi J Smock
- ARUP Laboratories, Department of Pathology, University of Utah Health Sciences Center, Salt Lake City, Utah, USA.
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