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Yong J, MacDonald S, Downey C, Fretwell R, Lawrence C, Murphy P, Pitchford T, Dutt T. Practical Considerations for the Use of the Rapid AcuStar ® ADAMTS13 Activity Assay in the Diagnosis of Acute Thrombotic Thrombocytopenic Purpura (TTP). J Clin Med 2024; 13:4462. [PMID: 39124729 PMCID: PMC11313591 DOI: 10.3390/jcm13154462] [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: 05/09/2024] [Revised: 07/19/2024] [Accepted: 07/20/2024] [Indexed: 08/12/2024] Open
Abstract
Introduction: Conventional practice in the management of acute TTP entails empirical treatment of suspected cases whilst awaiting confirmatory ADAMTS13 deficiency testing. Rapid ADAMTS13 assays offer increased accessibility and rapid diagnostics. The new automated HemosIL AcuStar® ADAMTS13 assay has seen increasing use among UK TTP Specialist Centres alongside the traditional ELISA method to confirm severe ADAMTS13 deficiency. Methods: A multi-centre retrospective case-control study was performed to review patients demonstrating discrepant ADAMTS13 activity results measured using rapid (AcuStar®) and ELISA assays in parallel from September 2019 to December 2021. Cases were compared with a cohort of suspected TTP patients exhibiting no difference in assay results and in relation to their presenting characteristics and pre-test probability of a diagnosis of TTP. Results: Where the clinical index of suspicion for TTP was high at presentation, acute TTP was confirmed using the AcuStar® assay < 0.2 IU/dL and subsequently < 10 IU/dL by ELISA with zero incidence of discrepancy. For patients with low clinical suspicion of acute TTP, a discrepancy between the AcuStar® and ELISA assay results was observed in 2% of cases; 5-10 IU/dL in AcuStar®, confirmed as >20 IU/dL by ELISA. A concurrent cancer diagnosis or sepsis was observed in 40% of discrepant cases. Conclusions: Where acute TTP is strongly suspected, there is a good correlation between the rapid AcuStar® ADAMTS13 assay and the conventional ELISA assay. Where the clinical suspicion of acute TTP is low, caution should be exercised in the interpretation of the ADAMTS13 activity using the AcuStar® assay. Accurate interpretation requires robust ADAMTS13 testing algorithms to be incorporated into diagnostic pathways.
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Affiliation(s)
- Jun Yong
- Department of Clinical Infection, Microbiology and Immunology, University of Liverpool, Liverpool L69 3BX, UK;
- The Roald Dahl Centre for Haemostasis and Thrombosis, Liverpool University Hospital NHS Trust, Liverpool L7 8XP, UK;
| | - Stephen MacDonald
- Cambridge Haemophilia and Thrombophilia Centre, Cambridge University Hospitals NHS Foundation Trust, Cambridge CB2 0QQ, UK;
| | - Colin Downey
- The Roald Dahl Centre for Haemostasis and Thrombosis, Liverpool University Hospital NHS Trust, Liverpool L7 8XP, UK;
| | - Rebekah Fretwell
- Department of Coagulation, Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield S10 2JF, UK; (R.F.); (T.P.)
| | - Caroline Lawrence
- Department of Haemostasis, Glasgow Royal Infirmary, Glasgow G4 0SF, UK;
| | - Paul Murphy
- Haematology and Haemostasis, The Newcastle Upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE3 3HD, UK
| | - Thomas Pitchford
- Department of Coagulation, Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield S10 2JF, UK; (R.F.); (T.P.)
| | - Tina Dutt
- The Roald Dahl Centre for Haemostasis and Thrombosis, Liverpool University Hospital NHS Trust, Liverpool L7 8XP, UK;
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Prasannan N, Dragunaite B, Subhan M, Thomas M, de Groot R, Singh D, Vanhoorelbeke K, Scully M. Peak ADAMTS13 activity to assess ADAMTS13 conformation and risk of relapse in immune-mediated thrombotic thrombocytopenic purpura. Blood 2024; 143:2644-2653. [PMID: 38502824 DOI: 10.1182/blood.2023023269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 02/22/2024] [Accepted: 03/14/2024] [Indexed: 03/21/2024] Open
Abstract
ABSTRACT Previous studies have demonstrated that >38% of patients with immune-mediated thrombotic thrombocytopenic purpura in remission with activity >50% had an open ADAMTS13 (a disintegrin and metalloproteinase with thrombospondin type 1 motif, member 13) conformation. We assessed ADAMTS13 conformation in remission (ADAMTS13 activity >60%), focusing on peak ADAMTS13 activity levels and longitudinal assessment in 420 samples across 157 patients. Fewer cases had an open conformation at peak ADAMTS13 activity than unselected remission samples with ADAMTS13 activity >60% (23% vs 43%). Patients with a closed ADAMTS13 conformation at peak ADAMTS13 activity had an eightfold lower relapse rate in the subsequent year (9% vs 46%) and a fivefold lower relapse rate within 2 years (23% vs 62%) compared with cases with an open conformation. Patients with an open conformation at peak ADAMTS13 activity required preemptive anti-CD20 treatment earlier than those with a closed conformation (median, 10 vs 25 months). Longitudinally, an open conformation was evident at, and often preceded relapse. When the conformation was already open before relapse, an increase in the conformation index at relapse was seen despite the undetectable anti-ADAMTS13 immunoglobulin G (IgG) antibody. In cases with detectable anti-ADAMTS13 IgG antibody, these became undetectable before achieving a closed conformation, highlighting the relapse risk even with undetectable anti-ADAMTS13 IgG antibody and the clinical utility of open/closed during monitoring. To our knowledge, this is the first study to show an association between relapse risk and ADAMTS13 conformation when activity levels are at a peak. The open conformation identifies antibody-mediated subclinical disease that is not detectable by the current ADAMTS13 testing.
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Affiliation(s)
- Nithya Prasannan
- Department of Haematology, University College London Hospitals NHS Foundation Trust, London, United Kingdom
- Haemostasis Research Unit, Institute of Cardiovascular Science, University College London, London, United Kingdom
| | - Bertina Dragunaite
- Haemostasis Research Unit, Institute of Cardiovascular Science, University College London, London, United Kingdom
| | - Maryam Subhan
- Haemostasis Research Unit, Institute of Cardiovascular Science, University College London, London, United Kingdom
| | - Mari Thomas
- Department of Haematology, University College London Hospitals NHS Foundation Trust, London, United Kingdom
- Haemostasis Research Unit, Institute of Cardiovascular Science, University College London, London, United Kingdom
- National Institute for Health Research Cardiometabolic Programme, Cardiovascular BRC, University College London Hospital/University College London, London, United Kingdom
| | - Rens de Groot
- Haemostasis Research Unit, Institute of Cardiovascular Science, University College London, London, United Kingdom
| | - Deepak Singh
- Special Coagulation, Health Services Laboratories, London, United Kingdom
| | - Karen Vanhoorelbeke
- Laboratory for Thrombosis Research, Interdisciplinary Research Facility Life Sciences, Katholieke Universiteit Leuven Campus Kulak Kortrijk, Kortrijk, Belgium
| | - Marie Scully
- Department of Haematology, University College London Hospitals NHS Foundation Trust, London, United Kingdom
- Haemostasis Research Unit, Institute of Cardiovascular Science, University College London, London, United Kingdom
- National Institute for Health Research Cardiometabolic Programme, Cardiovascular BRC, University College London Hospital/University College London, London, United Kingdom
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Allen C, Ito S, Butt A, Purcell A, Richmond R, Tormey CA, Krumholz HM, Cuker A, Goshua G. Cost-effectiveness of rapid vs in-house vs send-out ADAMTS13 testing for immune thrombotic thrombocytopenic purpura. Blood Adv 2024; 8:2279-2289. [PMID: 38502197 PMCID: PMC11116991 DOI: 10.1182/bloodadvances.2024012608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Revised: 02/27/2024] [Accepted: 03/11/2024] [Indexed: 03/21/2024] Open
Abstract
ABSTRACT While awaiting confirmatory results, empiric therapy for patients suspected to have immune thrombotic thrombocytopenic purpura (iTTP) provides benefits and also accrues risks and costs. Rapid assays for ADAMTS13 may be able to avoid the cost and risk exposure associated with empiric treatment. We conducted, to our knowledge, the first cost-effectiveness evaluation of testing strategies with rapid vs traditional ADAMTS13 assays in patients with intermediate- to high-risk PLASMIC scores, with and without caplacizumab use. We built a Markov cohort simulation with 4 clinical base-case analyses: (1) intermediate-risk PLASMIC score with caplacizumab; (2) intermediate-risk PLASMIC score without caplacizumab; (3) high-risk PLASMIC score with caplacizumab; and (4) high-risk PLASMIC score without caplacizumab. Each of these evaluated 3 testing strategies: (1) rapid assay (<1-hour turnaround); (2) in-house fluorescence resonance energy transfer (FRET)-based assay (24-hour turnaround); and (3) send-out FRET-based assay (72-hour turnaround). The primary outcome was the incremental net monetary benefit reported over a 3-day time horizon and across accepted willingness-to-pay thresholds in US dollars per quality-adjusted life-year (QALY). While accruing the same amount of QALYs, the rapid assay strategy saved up to $46 820 (95% CI, $41 961-$52 486) per patient tested. No parameter variation changed the outcome. In probabilistic sensitivity analyses, the rapid assay strategy was favored in 100% (3 base cases and scenario analyses) and 99% (1 base-case and scenario analysis) across 100 000 Monte Carlo iterations within each. Rapid ADAMTS13 testing for patients with intermediate- or high-risk PLASMIC scores yields significant per patient cost savings, achieved by reducing the costs associated with unnecessary therapeutic plasma exchange and caplacizumab therapy in patients without iTTP.
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Affiliation(s)
- Cecily Allen
- Division of Hematology, Department of Medicine, Johns Hopkins University, Baltimore, MD
| | - Satoko Ito
- Section of Hematology, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT
| | - Ayesha Butt
- Department of Internal Medicine, Yale University School of Medicine, New Haven, CT
| | | | | | - Christopher A. Tormey
- Department of Laboratory Medicine, Yale University School of Medicine, New Haven, CT
| | - Harlan M. Krumholz
- Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT
- Center for Outcomes Research and Evaluation, Yale New Haven Hospital, New Haven, CT
| | - Adam Cuker
- Department of Medicine and Department of Pathology & Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - George Goshua
- Section of Hematology, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT
- Center for Outcomes Research and Evaluation, Yale New Haven Hospital, New Haven, CT
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Dimopoulos K, Tripodi A, Goetze JP. Laboratory investigation and diagnosis of thrombotic thrombocytopenic purpura. Crit Rev Clin Lab Sci 2023; 60:625-639. [PMID: 37452521 DOI: 10.1080/10408363.2023.2232039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 04/04/2023] [Accepted: 06/27/2023] [Indexed: 07/18/2023]
Abstract
Thrombotic thrombocytopenic purpura (TTP) is a rare and potentially fatal disease for which rapid diagnosis is crucial for patient outcomes. Deficient activity (< 10%) of the liver enzyme, ADAMTS13, is the pathophysiological hallmark of TTP, and measurement of the enzyme activity can establish the diagnosis of TTP with high accuracy. Thus, along with the clinical history, appropriate laboratory assessment of a suspected case of TTP is essential for diagnosis and treatment. Here, we present a review of the available laboratory tests that can assist clinicians in establishing the diagnosis of TTP, with special focus on ADAMTS13 assays, including the measurement of the antigen and activity, and detection of autoantibodies to ADAMTS13.
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Affiliation(s)
- Konstantinos Dimopoulos
- Department of Clinical Biochemistry, Rigshospitalet, University Hospital of Copenhagen, Copenhagen, Denmark
| | - Armando Tripodi
- IRCCS Maggiore Hospital Foundation, Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Milano, Italy
| | - Jens P Goetze
- Department of Clinical Biochemistry, Rigshospitalet, University Hospital of Copenhagen, Copenhagen, Denmark
- Department of Biomedical Sciences, Faculty of Health, Copenhagen University, Copenhagen, Denmark
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5
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Irsara C, Anliker M, Egger AE, Harasser L, Lhotta K, Feistritzer C, Griesmacher A, Loacker L. Evaluation of two fully automated ADAMTS13 activity assays in comparison to manual FRET assay. Int J Lab Hematol 2023; 45:758-765. [PMID: 37194625 DOI: 10.1111/ijlh.14090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Accepted: 05/03/2023] [Indexed: 05/18/2023]
Abstract
INTRODUCTION The objective of the present study was to evaluate and compare the validity and utility of two fully automated ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) activity assays for clinical diagnostic decision-making and to compare their performance. METHODS Two automated ADAMTS13 activity assays (Werfen HemosIL® AcuStar ADAMTS13 Activity, Technoclone Technofluor ADAMTS13 Activity) were compared with a manual FRET assay (BioMedica ACTIFLUOR ADAMTS13 Activity). The following samples were used: 13 acute phase TTP (thrombotic thrombocytopenic purpura) samples from 11 different patients, one sample from a patient with congenital ADAMTS13 deficiency, 16 samples from control patients, three follow-up samples from TTP patients in long-term remission and one sample from a patient with stem cell transplantation related thrombotic microangiopathy (TMA). The WHO 1st International Standard for ADAMTS13 and several dilutions of normal plasma with ADAMTS13-depleted normal plasma were also tested. Statistical analysis included descriptive statistics, sensitivity and specificity, Passing & Bablok regression and Bland-Altman plot. RESULTS The quantitative comparison between the HemosIL® (x) and Technofluor (y) methods showed a strong correlation (Pearson r = 0.98, n = 49). When considering an ADAMTS13 activity of <10% as a hallmark for the diagnosis of TTP, two fully automated assays were both able to identify all TTP- and non-TTP-samples correctly, resulting in sensitivities and specificities of 100%. CONCLUSION Both fully automated ADAMTS13 activity assays showed a good diagnostic performance and quantitative correlation among themselves, discriminating reliably between TTP- and non-TTP-patients.
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Affiliation(s)
- Christian Irsara
- Central Institute of Clinical and Chemical Laboratory Diagnostics, University Hospital of Innsbruck, Innsbruck, Austria
| | - Markus Anliker
- Central Institute of Clinical and Chemical Laboratory Diagnostics, University Hospital of Innsbruck, Innsbruck, Austria
| | - Alexander E Egger
- Central Institute of Clinical and Chemical Laboratory Diagnostics, University Hospital of Innsbruck, Innsbruck, Austria
| | - Lukas Harasser
- Department of Internal Medicine IV, Nephrology and Hypertension, Innsbruck Medical University, Innsbruck, Austria
| | - Karl Lhotta
- Department of Internal Medicine III, Nephrology and Dialysis, Academic Teaching Hospital Feldkirch, Feldkirch, Austria
| | - Clemens Feistritzer
- Department of Internal Medicine V, Hematology and Oncology, Medical University of Innsbruck, Innsbruck, Austria
| | - Andrea Griesmacher
- Central Institute of Clinical and Chemical Laboratory Diagnostics, University Hospital of Innsbruck, Innsbruck, Austria
| | - Lorin Loacker
- Central Institute of Clinical and Chemical Laboratory Diagnostics, University Hospital of Innsbruck, Innsbruck, Austria
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6
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Butt A, Allen C, Purcell A, Ito S, Goshua G. Global Health Resource Utilization and Cost-Effectiveness of Therapeutics and Diagnostics in Immune Thrombotic Thrombocytopenic Purpura (TTP). J Clin Med 2023; 12:4887. [PMID: 37568288 PMCID: PMC10420213 DOI: 10.3390/jcm12154887] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 06/28/2023] [Accepted: 07/21/2023] [Indexed: 08/13/2023] Open
Abstract
In this review, we examine the current landscape of health resource utilization and cost-effectiveness data in the care of patient populations with immune thrombotic thrombocytopenic purpura. We focus on the therapeutic (therapeutic plasma exchange, glucocorticoids, rituximab, caplacizumab) and diagnostic (ADAMTS13 assay) health technologies employed in the care of patients with this rare disease. Health resource utilization and cost-effectiveness data are limited to the high-income country context. Measurement of TTP-specific utility weights in the high-income country context and collection of health resource utilization data in the low- and middle-income country settings would enable an evaluation of country-specific quality-adjusted life expectancy and cost-effectiveness of these therapeutic and diagnostic health technologies. This quantification of value is one way to mitigate cost concerns where they exist.
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Affiliation(s)
- Ayesha Butt
- Department of Internal Medicine, Yale School of Medicine, New Haven, CT 06510, USA
| | - Cecily Allen
- Division of Hematology, Department of Medicine, Johns Hopkins University, Baltimore, MD 21218, USA
| | | | - Satoko Ito
- Section of Hematology, Department of Internal Medicine, Yale School of Medicine, New Haven, CT 06510, USA
| | - George Goshua
- Section of Hematology, Department of Internal Medicine, Yale School of Medicine, New Haven, CT 06510, USA
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7
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Moore GW, Llusa M, Griffiths M, Binder NB. ADAMTS13 Activity Measurement by ELISA and Fluorescence Resonance Energy Transfer Assay. Methods Mol Biol 2023; 2663:533-547. [PMID: 37204735 DOI: 10.1007/978-1-0716-3175-1_35] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Accurate estimation of ADAMTS13 (a disintegrin-like and metalloprotease with thrombospondin type 1 motif, member 13) activity level is crucial in the diagnostic setting of differentiation between thrombotic thrombocytopenic purpura (TTP) and other thrombotic microangiopathies. The original assays were too cumbersome and time-consuming for use in the acute situation, and treatment was often based on clinical findings alone, with confirmatory laboratory assays following days or weeks later. Rapid assays are now available that can generate results fast enough to impact on immediate diagnosis and management. Assays based on fluorescence resonance energy transfer (FRET) or chemiluminescence principles can generate results in less than an hour, although they require specific analytical platforms. Enzyme-linked immunosorbent assays (ELISA) can generate results in about 4 h, but do not require specialized equipment beyond ELISA plate readers that are in regular use in many laboratories. The present chapter describes principles, performance, and practical aspects of an ELISA and a FRET assay, for quantitative measurement of ADAMTS13 activity in plasma.
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Affiliation(s)
- Gary W Moore
- Research and Development, Technoclone Herstellung von Diagnostika und Arzneimitteln GmbH, Vienna, Austria.
- Department of Haematology, Specialist Haemostasis Unit, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK.
- Department of Natural Sciences, Faculty of Science and Technology, Middlesex University London, London, UK.
| | - Marcos Llusa
- Research and Development, Technoclone Herstellung von Diagnostika und Arzneimitteln GmbH, Vienna, Austria
| | - Margaret Griffiths
- Research and Development, Technoclone Herstellung von Diagnostika und Arzneimitteln GmbH, Vienna, Austria
| | - Nikolaus B Binder
- Research and Development, Technoclone Herstellung von Diagnostika und Arzneimitteln GmbH, Vienna, Austria
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8
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Moore GW, Vetr H, Binder NB. ADAMTS13 Antibody and Inhibitor Assays. Methods Mol Biol 2023; 2663:549-565. [PMID: 37204736 DOI: 10.1007/978-1-0716-3175-1_36] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
A finding of an ADAMTS13 (a disintegrin-like and metalloprotease with thrombospondin type 1 motif, member 13) activity level of <10% of normal is usually sufficient to distinguish thrombotic thrombocytopenic purpura (TTP) from other thrombotic microangiopathies. TTP can be congenital or acquired, the most common form being acquired immune-mediated TTP caused by autoantibodies than inhibit ADAMTS13 function and/or increase its clearance. Basic 1 + 1 mixing tests can detect the presence of inhibitory antibodies, and quantification can be achieved with Bethesda-type assays that measure loss of function in a series of mixtures of test plasma and normal plasma. Not all patients present with inhibitory antibodies, and here the ADAMTS13 deficiency may be caused by clearing antibodies alone, which are not detectable in functional assays. ELISA assays are commonly used to detect clearing antibodies via capture with recombinant ADAMTS13. Since they also detect inhibitory antibodies, they are the preferred assay, although they cannot distinguish between inhibitory and clearing antibodies. The present chapter describes principles, performance, and practical aspects of a commercial ADAMTS13 antibody ELISA and a generic approach to Bethesda-type assays for detecting inhibitory ADAMTS13 antibodies.
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Affiliation(s)
- Gary W Moore
- Research and Development, Technoclone Herstellung von Diagnostika und Arzneimitteln GmbH, Vienna, Austria.
- Specialist Haemostasis Unit, Department of Haematology, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK.
- Department of Natural Sciences, Faculty of Science and Technology, Middlesex University London, London, UK.
| | - Helga Vetr
- Research and Development, Technoclone Herstellung von Diagnostika und Arzneimitteln GmbH, Vienna, Austria
| | - Nikolaus B Binder
- Research and Development, Technoclone Herstellung von Diagnostika und Arzneimitteln GmbH, Vienna, Austria
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9
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Moore GW, Griffiths M, Binder NB. ADAMTS13 Activity: Screening Test Protocol. Methods Mol Biol 2023; 2663:523-531. [PMID: 37204734 DOI: 10.1007/978-1-0716-3175-1_34] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Accurate estimation of ADAMTS13 (a disintegrin-like and metalloprotease with thrombospondin type 1 motif, member 13) activity level is necessary for diagnosis and management of thrombotic microangiopathies (TMA). In particular, it permits distinction between thrombotic thrombocytopenic purpura (TTP) and other TMAs, prompting disorder appropriate treatment. Manual and automated quantitative assays of ADAMTS13 activity are commercially available, some providing results within less than an hour, but they require specialist equipment and personnel and tend to only be available in specialized diagnostic facilities. Technoscreen ADAMTS13 Activity is a rapid, commercially available, semiquantitative screening test employing flow-through technology and an ELISA activity assay principle. It is a simple to perform screening tool, not requiring specialist equipment or personnel. The colored end point is compared to a reference color chart containing four color intensity indicators corresponding to ADAMTS13 activity levels of 0, 0.1, 0.4, or 0.8 IU/mL. Reduced levels detected in the screening test should be confirmed by quantitative assay. The assay lends itself to use in nonspecialized laboratories, remote, and point-of-care settings.
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Affiliation(s)
- Gary W Moore
- Research and Development, Technoclone Herstellung von Diagnostika und Arzneimitteln GmbH, Vienna, Austria.
- Specialist Haemostasis Unit, Department of Haematology, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK.
- Department of Natural Sciences, Faculty of Science and Technology, Middlesex University London, London, UK.
| | - Margaret Griffiths
- Research and Development, Technoclone Herstellung von Diagnostika und Arzneimitteln GmbH, Vienna, Austria
| | - Nikolaus B Binder
- Research and Development, Technoclone Herstellung von Diagnostika und Arzneimitteln GmbH, Vienna, Austria
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10
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White A, Martin R, Sew K, Stucke A, Cook R. Economic impact of a rapid, on‐demand ADAMTS‐13 activity assay for the diagnosis of thrombotic thrombocytopenic purpura. Res Pract Thromb Haemost 2022; 6:e12711. [PMID: 35599707 PMCID: PMC9123086 DOI: 10.1002/rth2.12711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 02/04/2022] [Accepted: 03/02/2022] [Indexed: 11/11/2022] Open
Abstract
Background Thrombotic thrombocytopenic purpura (TTP) is a rare, life-threatening thrombotic microangiopathy (TMA), characterized by ADAMTS-13 activity <10%. ADAMTS-13 activity assays are typically performed in reference laboratories with a turnaround time of several days. First-line treatment for TTP, therapeutic plasma exchange (TPE), typically starts while results are pending. The automated, on-demand HemosIL AcuStar ADAMTS-13 Activity assay provides results in under an hour, which could reduce unnecessary TPE use and associated costs. Objectives To estimate the hospital budget impact in the United States, United Kingdom, and France of using a rapid ADAMTS-13 activity assay. Methods We compared routine use of a rapid assay in adults with TMA with a scenario in which results take 3 days. Model structure and variables were based on published literature, plus survey and interviews of five clinicians from the three countries. Costs for the ADAMTS-13 activity assays and TPE were included. Results Model results suggest that if an on-demand, rapid ADAMTS-13 activity assay is used, US, UK, and French hospitals could save $18 million, £1.2 million, and €1.6 million annually, respectively. This equates to $10 788, £3497, and €4700 saved per patient with TMA in the United States, United Kingdom, and France. The model is most sensitive to the exact split of diagnoses of TMA cases, as savings accrue from non-TTP diagnoses. Conclusions In patients with TMA, use of a rapid, on-demand ADAMTS-13 activity assay such as the HemosIL AcuStar ADAMTS-13 Activity assay has the potential to be cost saving for hospitals.
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Affiliation(s)
- Alicia White
- Economist Intelligence Unit (EIU) Health Policy and Clinical Evidence (HPCE) Practice London UK
| | - Rosie Martin
- Economist Intelligence Unit (EIU) Health Policy and Clinical Evidence (HPCE) Practice London UK
| | - Keven Sew
- EIU HPCE Practice Singapore Singapore
| | | | - Rob Cook
- Economist Intelligence Unit (EIU) Health Policy and Clinical Evidence (HPCE) Practice London UK
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Graça NAG, Joly BS, Voorberg J, Vanhoorelbeke K, Béranger N, Veyradier A, Coppo P. TTP: From empiricism for an enigmatic disease to targeted molecular therapies. Br J Haematol 2022; 197:156-170. [PMID: 35146746 PMCID: PMC9304236 DOI: 10.1111/bjh.18040] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 12/29/2021] [Accepted: 12/31/2021] [Indexed: 12/19/2022]
Abstract
The 100th anniversary of the first description of Thrombotic Thrombocytopenic Purpura (TTP) as a disease by Dr. Eli Moschcowitz approaches. For many decades, TTP remained mostly a mysterious fatal condition, where diagnosis was often post-mortem. Initially a pentad of symptoms was identified, a pattern that later revealed to be fallible. Sporadic observations led to empiric interventions that allowed for the first impactful breakthrough in TTP treatment, almost 70 years after its first description: the introduction of plasma exchange and infusions as treatments. The main body of knowledge within the field was gathered in the latest three decades: patient registries were set and proved crucial for advancements; the general mechanisms of disease have been described; the diagnosis was refined; new treatments and biomarkers with improvements on prognosis and management were introduced. Further changes and improvements are expected in the upcoming decades. In this review, we provide a brief historic overview of TTP, as an illustrative example of the success of translational medicine enabling to rapidly shift from a management largely based on empiricism to targeted therapies and personalized medicine, for the benefit of patients. Current management options and present and future perspectives in this still evolving field are summarized.
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Affiliation(s)
- Nuno A. G. Graça
- Department of Molecular Hematology, Sanquin‐Academic Medical CenterLandsteiner LaboratoryAmsterdamThe Netherlands
| | - Bérangère S. Joly
- Service d'hématologie biologique and EA3518‐ Institut universitaire d'hématologieGroupe Hospitalier Saint Louis‐Lariboisière, AP‐HP, Université Paris DiderotParisFrance
- Centre de Référence des Microangiopathies ThrombotiquesHôpital Saint‐Antoine, AP‐HPParisFrance
| | - Jan Voorberg
- Department of Molecular Hematology, Sanquin‐Academic Medical CenterLandsteiner LaboratoryAmsterdamThe Netherlands
- Department of Experimental Vascular MedicineAmsterdam UMCAmsterdamThe Netherlands
| | - Karen Vanhoorelbeke
- Laboratory for Thrombosis Research, IRF Life SciencesKU Leuven Campus Kulak KortrijkKortrijkBelgium
| | - Nicolas Béranger
- Service d'hématologie biologique and EA3518‐ Institut universitaire d'hématologieGroupe Hospitalier Saint Louis‐Lariboisière, AP‐HP, Université Paris DiderotParisFrance
- Centre de Référence des Microangiopathies ThrombotiquesHôpital Saint‐Antoine, AP‐HPParisFrance
| | - Agnès Veyradier
- Service d'hématologie biologique and EA3518‐ Institut universitaire d'hématologieGroupe Hospitalier Saint Louis‐Lariboisière, AP‐HP, Université Paris DiderotParisFrance
- Centre de Référence des Microangiopathies ThrombotiquesHôpital Saint‐Antoine, AP‐HPParisFrance
| | - Paul Coppo
- Centre de Référence des Microangiopathies ThrombotiquesHôpital Saint‐Antoine, AP‐HPParisFrance
- Service d'HématologieHôpital Saint‐Antoine, AP‐HPParisFrance
- Sorbonne UniversitéUPMC Univ ParisParisFrance
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Dimopoulos K, Philips M, Goetze JP. Diagnosis of Thrombotic Thrombocytopenic Purpura by ADAMTS13 Activity Quantification. J Appl Lab Med 2022; 7:637-649. [PMID: 34977929 DOI: 10.1093/jalm/jfab148] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2021] [Accepted: 09/13/2021] [Indexed: 11/12/2022]
Abstract
BACKGROUND Rapid quantification of ADAMTS13 activity in plasma is essential for establishing a diagnosis of thrombotic thrombocytopenic purpura (TTP); a rare, but potentially lethal disorder. The current methods for quantitating ADAMTS13 activity are manual and only available at specialized laboratories, which often results in initiation of specific treatments long before a diagnosis of TTP is established. METHODS We compared the performance of the HemosIL, a novel and rapid automated method, and the current standard FRET (fluorescence resonance energy transfer) method in quantitating ADAMTS13 activity using 706 consecutive plasma samples collected over a period of 14 years. The clinical accuracy of both methods was further examined using 212 diagnostic samples. RESULTS The correlation between the FRET and HemosIL methods in all 706 samples and in the 212 diagnostic samples was excellent (Pearson's r of 0.919 and 0.912, respectively). Both methods displayed a high degree of clinical accuracy using the current cutoff of ADAMTS13 activity <0.10 kIU/L (<10%) as diagnostic for TTP: the area under the curve (AUC) was 97.7% for the FRET method and 99.5% for the HemosIL method. When applying a lower cutoff (ADAMTS13 activity <0.05 kIU/L or <5%), the diagnostic accuracy of the HemosIL method increased further (AUC = 99.7%). CONCLUSIONS A novel, rapid method for ADAMTS13 quantification is comparable to the more laborious FRET method in patients with possible TTP. A rapid analysis available in the acute setting assessing patients with possible TTP allows for improved care and optimized treatment of a life-threatening condition.
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Affiliation(s)
- Konstantinos Dimopoulos
- Department of Clinical Biochemistry, Copenhagen University Hospital-Rigshospitalet, Copenhagen, Denmark
| | - Malou Philips
- Department of Clinical Biochemistry, Copenhagen University Hospital-Rigshospitalet, Copenhagen, Denmark
| | - Jens P Goetze
- Department of Clinical Biochemistry, Copenhagen University Hospital-Rigshospitalet, Copenhagen, Denmark.,Department of Biomedical Sciences, Faculty of Health, University of Copenhagen, Copenhagen, Denmark
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[Treatment of immune-mediated thrombotic thrombocytopenic purpura: A decisive turning point]. Transfus Clin Biol 2021; 28:380-385. [PMID: 34464709 DOI: 10.1016/j.tracli.2021.08.347] [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: 08/20/2021] [Accepted: 08/25/2021] [Indexed: 11/23/2022]
Abstract
Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a rare and life-threatening thrombotic microangiopathy characterized by severe deficiency of ADAMTS13, the enzyme that cleaves von Willebrand factor multimers. Recent insights into iTTP pathophysiology have led to the development of new therapies targeting ADAMTS13 replacement, anti-ADAMTS13 antibodies, and von Willebrand factor-platelet interactions. New maximalist therapeutic strategies are emerging based on triple therapy. While plasma exchange remains the cornerstone therapy of the acute phase, the introduction of front-line immunosuppressive treatments, corticosteroids and rituximab, has led to a reduction in exacerbations and relapses but without any significant improvement in survival. Caplacizumab, a bivalent humanized anti-von Willebrand factor nanobody, is poised to revolutionize the treatment of the acute phase. By inhibiting the interaction between von Willebrand factor multimers and platelets, caplacizumab prevents platelets adhesion, prevents the formation of new microthrombi and protects organs from ischemia. Its early combination with plasma exchange and immunosuppressive therapy prevents unfavorable outcomes and reduces the burden of care. Supported by repeated ADAMTS13 assays, rituximab prevents relapse in patients with persistent or recurrent ADAMTS13 deficiency in clinical remission. This review examines how advances in diagnostics and targeted therapies are changing the current treatment paradigm in both the acute and remission phases and are contributing to dramatically improve the iTTP prognosis.
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