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Bissola AL, Zhang Y, Cranstone M, Moore JC, Warkentin TE, Arnold DM, Nazy I. Evaluating Diagnostic Algorithms for Heparin-Induced Thrombocytopenia using Two Combined Automated Rapid Immunoassays. Semin Thromb Hemost 2024. [PMID: 38733981 DOI: 10.1055/s-0044-1786749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/13/2024]
Abstract
Heparin-induced thrombocytopenia (HIT) is an autoimmune disorder caused by antibodies against platelet factor 4 (PF4) and heparin complexes. Rapid immunoassays (IAs) for detection of these antibodies mark a milestone in HIT diagnosis, despite a higher false-positive rate compared with functional platelet-activation assays. However, combining different rapid IAs may help to improve their diagnostic specificity. Here, we compared the individual performance of the latex immunoturbidimetric assay (LIA; HemosIL HIT-Ab [PF4-H]; sensitivity 91.7%, specificity 68.4%) and chemiluminescence immunoassay (CLIA; HemosIL AcuStarHIT-Ab [PF4-H]; sensitivity 92.4%, specificity 85.8%) with their combined performance using two unique diagnostic algorithms in a single prospective cohort of suspected HIT patients. Using the simultaneous algorithm adapted from Warkentin et al, the combined LIA-CLIA had a sensitivity of 99.0% and specificity of 64.3%. The sequential algorithm adapted from Rittener-Ruff et al was applied in two theoretical scenarios to reflect real-world circumstances in diagnostic laboratories where access to clinical information is limited: (1) assuming all patients had an intermediate 4Ts score and (2) assuming all patients had a high 4Ts score. This algorithm correctly predicted HIT in 94.5% (high 4Ts) and 96.0% (intermediate 4Ts) and excluded HIT in 82.6% (high 4Ts) and 80.1% (intermediate 4Ts) of patients in either scenario, respectively. Although both combined algorithms improved diagnostic performance of individual IAs, the simultaneous algorithm showed fewer false predictions (7.9%) than the sequential algorithm (intermediate 4Ts: 37.6% and high 4Ts: 41.5%) and proved more practical as it does not rely on physician evaluations. Our findings highlight the importance of accounting for clinician and interlaboratory variability when evaluating diagnostic tests for HIT.
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Affiliation(s)
- Anna-Lise Bissola
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
- Michael G. DeGroote Centre for Transfusion Research, McMaster University, Hamilton, Ontario, Canada
| | - Yi Zhang
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
- Michael G. DeGroote Centre for Transfusion Research, McMaster University, Hamilton, Ontario, Canada
- Department of Biochemistry and Biomedical Sciences, McMaster University Hamilton, Ontario, Canada
| | - Madison Cranstone
- Michael G. DeGroote Centre for Transfusion Research, McMaster University, Hamilton, Ontario, Canada
- Department of Statistics and Actuarial Science, University of Waterloo, Waterloo, Ontario, Canada
| | - Jane C Moore
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
- Michael G. DeGroote Centre for Transfusion Research, McMaster University, Hamilton, Ontario, Canada
| | - Theodore E Warkentin
- Department of Pathology and Molecular Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
- Transfusion Medicine, Hamilton Regional Laboratory Medicine Program, Hamilton Health Sciences, Hamilton, Ontario, Canada
| | - Donald M Arnold
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
- Michael G. DeGroote Centre for Transfusion Research, McMaster University, Hamilton, Ontario, Canada
| | - Ishac Nazy
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
- Michael G. DeGroote Centre for Transfusion Research, McMaster University, Hamilton, Ontario, Canada
- Department of Biochemistry and Biomedical Sciences, McMaster University Hamilton, Ontario, Canada
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2
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Arachchillage DJ, Thachil J, Anderson JAM, Baker P, Poles A, Kitchen S, Laffan M. Diagnosis and management of heparin-induced thrombocytopenia: Third edition. Br J Haematol 2024; 204:459-475. [PMID: 38153164 DOI: 10.1111/bjh.19180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 10/16/2023] [Accepted: 10/19/2023] [Indexed: 12/29/2023]
Affiliation(s)
- Deepa J Arachchillage
- Centre for Haematology, Department of Immunology and Inflammation, Imperial College London, London, UK
- Department of Haematology, Imperial College Healthcare NHS Trust, London, UK
| | - Jecko Thachil
- Department of Haematology, Manchester Royal Infirmary, Manchester, UK
| | - Julia A M Anderson
- Department of Haematology, Edinburgh Royal Infirmary, Edinburgh, Scotland
| | - Peter Baker
- Oxford Haemophilia and Thrombosis Centre, Oxford University Hospitals NHS Trust, Oxford, UK
| | - Anthony Poles
- Bristol NHS Blood and Transplant Centre, Bristol, UK
| | - Steve Kitchen
- Department of Haematology, Royal Hallamshire Hospital, Sheffield, UK
| | - Mike Laffan
- Centre for Haematology, Department of Immunology and Inflammation, Imperial College London, London, UK
- Department of Haematology, Imperial College Healthcare NHS Trust, London, UK
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3
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Tucker CM, Rhoades R, Sharma R, Gong JZ. Optimization of laboratory diagnosis of heparin-induced thrombocytopenia using HemosIL-AcuStar-HIT-IgG assay. Lab Med 2024; 55:34-39. [PMID: 37094798 DOI: 10.1093/labmed/lmad029] [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] [Indexed: 04/26/2023] Open
Abstract
OBJECTIVE The aim of this study was to determine an optimal cutoff value for the newly available HemosIL-AcuStar-HIT-IgG assay (AcuStar) for the diagnosis of heparin-induced thrombocytopenia (HIT). METHOD We evaluated the performance of AcuStar using serotonin release assay (SRA) as the gold standard and incorporated 4T score calculation in a cohort of suspected HIT cases. Statistical analysis was performed to determine optimal cutoff value for the diagnosis of HIT. RESULT A diagnosis of HIT can be excluded with a platelet factor 4 (PF4) value of <0.4 U/mL by AcuStar and 4T score in the low-risk category (≤3). All other cases will require confirmation with a functional test. CONCLUSION Our study resulted in the implementation of a diagnostic algorithm for laboratory diagnosis of HIT, which incorporates pretest calculation of 4T score and AcuStar as a screening test, with reflex confirmation by SRA. This new algorithm resulted in extended hours of test availability and a more rapid turnaround time in reporting PF4 results.
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Affiliation(s)
- Catherine M Tucker
- Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Philadelphia, PA, US
| | - Ruben Rhoades
- Department of Medicine, Division of Hematology, Thomas Jefferson University, Philadelphia, PA, US
| | - Ruchika Sharma
- Department of Pediatrics, Division of Hematology/Oncology/BMT, Medical College of Wisconsin, Versiti Blood Research Institute, Milwaukee, WI,US
| | - Jerald Z Gong
- Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Philadelphia, PA, US
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4
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May J, Westbrook B, Cuker A. Heparin-induced thrombocytopenia: An illustrated review. Res Pract Thromb Haemost 2023; 7:100283. [PMID: 37601013 PMCID: PMC10439402 DOI: 10.1016/j.rpth.2023.100283] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 05/25/2023] [Accepted: 05/31/2023] [Indexed: 08/22/2023] Open
Abstract
Heparin-induced thrombocytopenia (HIT) is an immune-mediated adverse drug effect from unfractionated or low-molecular-weight heparin that results in thrombocytopenia and potentially catastrophic thrombosis. HIT occurs due to the development of platelet-activating antibodies against multimolecular complexes of platelet factor 4 and heparin. Given the frequency of thrombocytopenia and heparin use among hospitalized patients, calculation of the 4Ts Score is recommended to identify patients at increased likelihood of HIT and direct further evaluation. In patients with an intermediate or high probability 4Ts Score, an immunoassay and functional assay are recommended to confirm or refute the diagnosis of HIT. Heparin avoidance and initiation of nonheparin anticoagulation are the mainstays of acute HIT management. In this illustrated review, we provide visual summaries of the diagnosis and management of HIT, highlighting connections between pathophysiology and clinical care as well as summarizing efforts in quality improvement in the field. We further emphasize common pitfalls and pearls in diagnosis and management to encourage evidence-based care. We include graphical representation of the unique challenges of HIT with cardiopulmonary bypass and also delineate autoimmune HIT and its subtypes.
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Affiliation(s)
- Jori May
- Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Brian Westbrook
- Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Adam Cuker
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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5
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Chen LY, Schirmer U, Widder M, Gruel Y, Rollin J, Zipfel PF, Nguyen TH. Breast cancer cell-based ELISA: a potential material for better detection of heparin-induced thrombocytopenia antibodies. J Mater Chem B 2022; 10:7708-7716. [PMID: 36069407 DOI: 10.1039/d2tb01228f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Heparin-induced thrombocytopenia (HIT) is caused by newly formed platelet-activating antibodies against complexes formed between platelet factor 4 (PF4) and heparin (H). HIT can result in life-threatening complications; thus, early detection of HIT antibodies is crucial for the treatment of the disease. The enzyme-linked immune absorbance assay (ELISA) for the identification of HIT antibodies is widely used in many laboratories, but in general, this test provides only ∼50% accuracy while other methods show multiple limitations. Here, we developed a new cell-based ELISA to improve the detection of HIT antibodies. Instead of immobilizing PF4 or PF4/H complexes directly onto a plate as in the standard ELISA, we added the complexes on breast cancer cells, i.e., cell line MDA-MB-231, and applied the same protocol for antibody detection. Using confocal laser scanning microscopy and flow cytometry for the characterization of bound complexes, we identified two types of HIT-mimicked antibodies (KKO and 1E12), which were able to differentiate from the non-HIT antibody (RTO). PF4-treated MDA-MB-231 cells allowed binding of HIT-mimicked antibodies better than PF4/H complexes. With human sera, the cell-based ELISA allowed better differentiation of clinically relevant from non-clinically relevant HIT antibodies as compared with the standard ELISA. Our findings provide a potential approach that contributes to the development of better assays for the detection of HIT antibodies.
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Affiliation(s)
- Li-Yu Chen
- Institute for Bioprocessing and Analytical Measurement Techniques, Heiligenstadt, Germany.,Department of Infection Biology, Leibniz Institute for Natural Product Research and Infection Biology, Jena, Germany
| | - Uwe Schirmer
- Institute for Bioprocessing and Analytical Measurement Techniques, Heiligenstadt, Germany
| | - Miriam Widder
- Institute for Bioprocessing and Analytical Measurement Techniques, Heiligenstadt, Germany
| | - Yves Gruel
- Université de Tours, EA7501 GICC, Tours, France.,Chu Tours, Laboratoire d'Hématologie-Hémostase, Tours, France
| | - Jérôme Rollin
- Université de Tours, EA7501 GICC, Tours, France.,Chu Tours, Laboratoire d'Hématologie-Hémostase, Tours, France
| | - Peter F Zipfel
- Department of Infection Biology, Leibniz Institute for Natural Product Research and Infection Biology, Jena, Germany
| | - Thi-Huong Nguyen
- Institute for Bioprocessing and Analytical Measurement Techniques, Heiligenstadt, Germany.,Institute for Chemistry and Biotechnology, Faculty of Mathematics and Natural Sciences, Technische Universität Ilmenau, 98694 Ilmenau, Germany.
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6
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Aguiar de Sousa D, Romoli M, Sánchez Van Kammen M, Heldner MR, Zini A, Coutinho JM, Arnold M, Ferro JM. Cerebral Venous Thrombosis in Patients With Heparin-Induced Thrombocytopenia a Systematic Review. Stroke 2022; 53:1892-1903. [PMID: 35240862 DOI: 10.1161/strokeaha.121.036824] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
BACKGROUND Cerebral venous thrombosis (CVT) has recently been reported as a common thrombotic manifestation in association with vaccine-induced thrombotic thrombocytopenia, a syndrome that mimics heparin-induced thrombocytopenia (HIT) and occurs after vaccination with adenovirus-based SARS-CoV-2 vaccines. We aimed to systematically review the incidence, clinical features, and prognosis of CVT occurring in patients with HIT. METHODS The study protocol was registered with PROSPERO (CRD42021249652). MEDLINE, EMBASE and Cochrane CENTRAL were searched up to June 1, 2021 for HIT case series including >20 patients, or any report of HIT-related CVT. Demographic, neuroradiological, clinical, and mortality data were retrieved. Meta-analysis of proportions with random-effect modeling was used to derive rate of CVT in HIT and in-hospital mortality. Pooled estimates were compared with those for CVT without HIT and HIT without CVT, to determine differences in mortality. RESULTS From 19073 results, we selected 23 case series of HIT (n=1220) and 27 cases of HIT-related CVT (n=27, 71% female). CVT developed in 1.6% of 1220 patients with HIT (95% CI,1.0%-2.5%, I2=0%). Hemorrhagic brain lesions occurred in 81.8% of cases of HIT-related CVT and other concomitant thrombosis affecting other vascular territory was reported in 47.8% of cases. In-hospital mortality was 33.3%. HIT-related CVT carried a 29% absolute increase in mortality rate compared with historical CVT controls (33.3% versus 4.3%, P<0.001) and a 17.4% excess mortality compared with HIT without CVT (33.3% versus 15.9%, P=0.046). CONCLUSIONS CVT is a rare thrombotic manifestation in patients with HIT. HIT-related CVT has higher rates of intracerebral hemorrhage and a higher mortality risk, when compared with CVT in historical controls. The recently reported high frequency of CVT in patients with vaccine-induced thrombotic thrombocytopenia was not observed in HIT, suggesting that additional pathophysiological mechanisms besides anti-platelet factor-4 antibodies might be involved in vaccine-induced thrombotic thrombocytopenia-related CVT.
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Affiliation(s)
- Diana Aguiar de Sousa
- Department of Neurology, Centro Hospitalar Universitário de Lisboa Norte - Hospital de Santa Maria, Lisbon, Portugal (D.A.d.S., J.M.F.).,Faculdade de Medicina, Universidade de Lisboa, Portugal (D.A.d.S., J.M.F.)
| | - Michele Romoli
- Neurology and Stroke Unit, "Maurizio Bufalini" Hospital, Cesena, Italy (M.R.).,Neurology Clinic, University of Perugia - S. Maria della Misericordia Hospital, Italy (M.R.)
| | - Mayte Sánchez Van Kammen
- Department of Neurology, Amsterdam University Medical Center, the Netherlands (M.S.V.K., J.M.C.)
| | - Mirjam R Heldner
- Department of Neurology, University hospital and University of Bern, Switzerland (M.R.H., M.A.)
| | - Andrea Zini
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Neurologia e Rete Stroke Metropolitana, Ospedale Maggiore, Bologna, Italy (A.Z.)
| | - Jonathan M Coutinho
- Department of Neurology, Amsterdam University Medical Center, the Netherlands (M.S.V.K., J.M.C.)
| | - Marcel Arnold
- Department of Neurology, University hospital and University of Bern, Switzerland (M.R.H., M.A.)
| | - José M Ferro
- Department of Neurology, Centro Hospitalar Universitário de Lisboa Norte - Hospital de Santa Maria, Lisbon, Portugal (D.A.d.S., J.M.F.).,Faculdade de Medicina, Universidade de Lisboa, Portugal (D.A.d.S., J.M.F.)
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7
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Pishko AM, Cuker A. Diagnosing heparin-induced thrombocytopenia: The need for accuracy and speed. Int J Lab Hematol 2021; 43 Suppl 1:96-102. [PMID: 34288442 DOI: 10.1111/ijlh.13564] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Revised: 04/06/2021] [Accepted: 04/14/2021] [Indexed: 01/15/2023]
Abstract
Heparin-induced thrombocytopenia (HIT) is a prothrombotic condition resulting from pathogenic antibodies to complexes of heparin and platelet factor 4 (PF4). The diagnosis of HIT can be challenging due to the widespread use of heparin and the frequency of thrombocytopenia in hospitalized patients. Laboratory testing for HIT typically includes an immunoassay to detect antibodies to PF4-heparin and a functional assay. Current HIT diagnostic algorithms recommend using the 4Ts score to determine the need for HIT laboratory testing. Automated calculation of HIT clinical prediction scores in the electronic health record may improve the identification of patients who should undergo HIT testing. Another challenge in the management of patients with suspected HIT is the turnaround time of the laboratory testing needed to confirm the diagnosis. Due to the high daily thrombotic risk of HIT, clinicians must treat patients with intermediate to high pretest likelihood of HIT empirically while awaiting the test results. Treatment for HIT often involves alternative anticoagulants that lack reversal agents, which may increase bleeding risk, prolong hospital stays, and increase costs for patients suspected of having HIT. Rapid immunoassays hold promise to improve the speed of HIT diagnosis. These assays must retain a very high sensitivity for this "can't miss" diagnosis, yet have sufficient specificity to be of diagnostic value. A Bayesian approach has been proposed using two rapid immunoassays in succession, which decreased analytic turnaround time to 60 minutes. Such an approach has the potential to be a much-needed clinical advance in improving accuracy and speed in the diagnosis of HIT.
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Affiliation(s)
- Allyson M Pishko
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Adam Cuker
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.,Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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8
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Platton S, Bartlett A, MacCallum P, Makris M, McDonald V, Singh D, Scully M, Pavord S. Evaluation of laboratory assays for anti-platelet factor 4 antibodies after ChAdOx1 nCOV-19 vaccination. J Thromb Haemost 2021; 19:2007-2013. [PMID: 33973336 PMCID: PMC8236994 DOI: 10.1111/jth.15362] [Citation(s) in RCA: 93] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 05/03/2021] [Indexed: 01/13/2023]
Abstract
INTRODUCTION Vaccine-induced immune thrombocytopenia and thrombosis (VITT) following ChAdOx1 nCOV-19 vaccine has been described, associated with unusual site thrombosis, thrombocytopenia, raised D-dimer, and high-titer immunoglobulin-G (IgG) class anti-platelet factor 4 (PF4) antibodies. Enzyme-linked immunosorbent assays (ELISA) have been shown to detect anti-PF4 in patients with VITT, but chemiluminescence assays do not reliably detect them. ELISA assays are not widely available in diagnostic laboratories, and, globally, very few laboratories perform platelet activation assays. METHODS Assays that are commercially available in the United Kingdom were evaluated for their ability to identify anti-PF4 antibodies in samples from patients with suspected VITT. Four IgG-specific ELISAs, two polyspecific ELISAs, and four rapid assays were performed on samples from 43 patients with suspected VITT from across the United Kingdom. Cases were identified after referral to the UK Expert Haematology Panel multidisciplinary team and categorized into unlikely, possible, or probable VITT. RESULTS AND DISCUSSION We demonstrated that the HemosIL AcuStar HIT-IgG, HemosIL HIT-Ab, Diamed PaGIA gel, and STic Expert assays have poor sensitivity for VITT in comparison to ELISA. Where these assays are used for heparin-induced thrombocytopenia (HIT) diagnosis, laboratories should ensure that requests for suspected VITT are clearly identified so that an ELISA is performed. No superiority of IgG-ELISAs over polyspecific ELISAs in sensitivity to VITT could be demonstrated. No single ELISA method detected all possible/probable VITT cases; if a single ELISA test is negative, a second ELISA or a platelet activation assay should be considered where there is strong clinical suspicion.
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Affiliation(s)
- Sean Platton
- The Royal London Haemophilia CentreBarts Health NHS TrustLondonUK
- NHS East and South East London Pathology PartnershipBarts Health NHS TrustLondonUK
| | - Andrew Bartlett
- NHS East and South East London Pathology PartnershipBarts Health NHS TrustLondonUK
- Lewisham and Greenwich NHS TrustLondonUK
| | - Peter MacCallum
- Barts and The London School of Medicine and DentistryQueen Mary University of LondonLondonUK
- Department of HaematologyBarts Health NHS TrustLondonUK
| | - Mike Makris
- Department of Infection, Immunity and Cardiovascular DiseaseUniversity of SheffieldSheffieldUK
- Sheffield Haemophilia and Thrombosis CentreSheffield Teaching Hospitals NHS Foundation TrustSheffieldUK
| | - Vickie McDonald
- The Royal London Haemophilia CentreBarts Health NHS TrustLondonUK
- Department of HaematologyBarts Health NHS TrustLondonUK
| | - Deepak Singh
- Special CoagulationHealth Service LaboratoriesLondonUK
| | - Marie Scully
- Department of HaematologyUniversity College London Hospitals NHS Foundation TrustLondonUK
- National Institute for Health ResearchUniversity College London Hospitals Biomedical Research CentreLondonUK
| | - Sue Pavord
- Oxford University Hospitals NHS Foundation TrustOxfordUK
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9
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Warkentin TE, Smythe MA, Ali MA, Aslam N, Sheppard JI, Smith JW, Moore JC, Arnold DM, Nazy I. Serotonin-release assay-positive but platelet factor 4-dependent enzyme-immunoassay negative: HIT or not HIT? Am J Hematol 2021; 96:320-329. [PMID: 33326124 DOI: 10.1002/ajh.26075] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 12/07/2020] [Accepted: 12/14/2020] [Indexed: 12/28/2022]
Abstract
IgG-specific and polyspecific PF4-dependent enzyme-immunoassays (EIAs) have exceptionally high sensitivity (≥99%) for diagnosis of heparin-induced thrombocytopenia (HIT), a drug reaction caused by platelet-activating antibodies detectable by serotonin-release assay (SRA). The IgG-specific EIAs are recommended for screening, as their high sensitivity is accompanied by relatively high specificity vis-à-vis polyspecific EIAs. We investigated the frequency of SRA-positive/EIA-negative (SRA+/EIA-) HIT, prompted by referral to our reference HIT laboratory of serial blood samples from a patient ("index case") with false-negative IgG-specific EIAs. Despite initial clinical suspicion for HIT, repeat negative IgG-specific EIAs prompted heparin resumption, which triggered recurrent thrombocytopenia and near-fatal cardiac arrest, indicating likely post-heparin HIT-associated anaphylactoid reaction. Further investigations revealed a strong-positive SRA, whether performed with heparin alone, PF4 alone, or PF4/heparin, with inhibition by Fc receptor-blocking monoclonal antibody (indicating IgG-mediated platelet activation); however, five different IgG-specific immunoassays yielded primarily negative (or weak-positive) results. To investigate the frequency of SRA+/EIA- HIT, we reviewed the laboratory and clinical features of patients with this serological profile during a 6-year period in which our reference laboratory investigated for HIT using both SRA and IgG-specific EIA. Although ~0.2% of 8546 patients had an SRA+/EIA- profile, further review of 15 such cases indicated clerical/laboratory misclassification or false-positive SRA in all, with no SRA+/EIA- HIT case identified. We conclude that while SRA+/EIA- HIT is possible-as shown by our index case-this clinical picture is exceptionally uncommon. Moreover, the requirement for a positive EIA is a useful quality control maneuver that reduces risk of reporting a false-positive SRA result.
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Affiliation(s)
- Theodore E. Warkentin
- Department of Pathology and Molecular Medicine Michael G. DeGroote School of Medicine Hamilton Ontario Canada
- Department of Medicine Michael G. DeGroote School of Medicine Hamilton Ontario Canada
- McMaster Centre for Transfusion Research Hamilton Ontario Canada
| | - Maureen A. Smythe
- Department of Pharmaceutical Services Beaumont Hospital Royal Oak Michigan USA
- Department of Pharmacy Practice Wayne State University Detroit Michigan USA
- Oakland University William Beaumont School of Medicine Rochester Michigan USA
| | - Mona A. Ali
- Department of Pharmaceutical Services Beaumont Hospital Royal Oak Michigan USA
| | - Naveed Aslam
- Oakland University William Beaumont School of Medicine Rochester Michigan USA
| | - Jo‐Ann I. Sheppard
- Department of Pathology and Molecular Medicine Michael G. DeGroote School of Medicine Hamilton Ontario Canada
| | - James W. Smith
- Department of Medicine Michael G. DeGroote School of Medicine Hamilton Ontario Canada
| | - Jane C. Moore
- Department of Medicine Michael G. DeGroote School of Medicine Hamilton Ontario Canada
| | - Donald M. Arnold
- Department of Medicine Michael G. DeGroote School of Medicine Hamilton Ontario Canada
- McMaster Centre for Transfusion Research Hamilton Ontario Canada
| | - Ishac Nazy
- Department of Medicine Michael G. DeGroote School of Medicine Hamilton Ontario Canada
- McMaster Centre for Transfusion Research Hamilton Ontario Canada
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10
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Marcucci R, Berteotti M, Gori AM, Giusti B, Rogolino AA, Sticchi E, Liotta AA, Ageno W, De Candia E, Gresele P, Marchetti M, Marietta M, Tripodi A. Heparin induced thrombocytopenia: position paper from the Italian Society on Thrombosis and Haemostasis (SISET). BLOOD TRANSFUSION = TRASFUSIONE DEL SANGUE 2021; 19:14-23. [PMID: 33370230 PMCID: PMC7850929 DOI: 10.2450/2020.0248-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 10/14/2020] [Indexed: 12/21/2022]
Abstract
Heparin induced thrombocytopenia (HIT) is a rare immune mediated adverse drug reaction occurring after exposure to heparin. It is a serious and potentially fatal condition, which may be associated with the development of arterial or venous thrombotic events. Although known for many years, HIT is still often misdiagnosed. Pre- test clinical probability, screening for anti-PF4/heparin antibodies and documentation of their platelet activating capacity are the cornerstones of diagnosis. However, both clinical algorithms and test modalities have limited predictive values and limited diffusion so that the diagnosis and management is challenging in the clinical practice. For this reason, there is an unmet need for novel rational non-anticoagulant therapies based on the pathogenesis of HIT.The present paper reports the position of the Italian Society on Haemostasis and Thrombosis (SISET) in order to increase awareness of HIT among clinicians and other health care professionals and to provide information on the most appropriate management.
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Affiliation(s)
- Rossella Marcucci
- Experimental and Clinical Medicine, University of Florence; Atherothrombotic Center, AOU Careggi, Florence, Italy
| | - Martina Berteotti
- Experimental and Clinical Medicine, University of Florence; Atherothrombotic Center, AOU Careggi, Florence, Italy
| | - Anna M. Gori
- Experimental and Clinical Medicine, University of Florence; Atherothrombotic Center, AOU Careggi, Florence, Italy
| | - Betti Giusti
- Experimental and Clinical Medicine, University of Florence; Atherothrombotic Center, AOU Careggi, Florence, Italy
| | - Angela A. Rogolino
- Experimental and Clinical Medicine, University of Florence; Atherothrombotic Center, AOU Careggi, Florence, Italy
| | - Elena Sticchi
- Experimental and Clinical Medicine, University of Florence; Atherothrombotic Center, AOU Careggi, Florence, Italy
| | - Agatina Alessandrello Liotta
- Experimental and Clinical Medicine, University of Florence; Atherothrombotic Center, AOU Careggi, Florence, Italy
| | - Walter Ageno
- Department of Medicine and Surgery, University of Insubria, Varese, Italy
| | - Erica De Candia
- Department of Translational Medicine and Surgery, Catholic University of Rome, Rome, Italy
- Department of Image Diagnostics, Radiotherapy and Haematology, Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Rome, Italy
| | - Paolo Gresele
- Department of Medicine, Section of Internal and Cardiovascular Medicine, University of Perugia, Perugia, Italy
| | - Marina Marchetti
- Department of Immunohematology and Transfusion Medicine, Hospital Papa Giovanni XXIII, Bergamo, Italy
| | - Marco Marietta
- Department of Oncology and Haematology, University Hospital, Modena, Italy
| | - Armando Tripodi
- IRCCS “Ca’ Granda Maggiore” Hospital Foundation, “Angelo Bianchi Bonomi” Haemophilia and Thrombosis Center and “Fondazione Luigi Villa”, Milan, Italy
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11
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Abstract
Heparin-induced thrombocytopenia is an immune-mediated disorder caused by antibodies that recognize complexes of platelet factor 4 and heparin. Thrombosis is a central and unpredictable feature of this syndrome. Despite optimal management, disease morbidity and mortality from thrombosis remain high. The hypercoagulable state in heparin-induced thrombocytopenia is biologically distinct from other thrombophilic disorders in that clinical complications are directly attributable to circulating ultra-large immune complexes. In some individuals, ultra-large immune complexes elicit unchecked cellular procoagulant responses that culminate in thrombosis. To date, the clinical and biologic risk factors associated with thrombotic risk in heparin-induced thrombocytopenia remain elusive. This review will summarize our current understanding of thrombosis in heparin-induced thrombocytopenia with attention to its clinical features, cellular mechanisms, and its management.
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Affiliation(s)
| | - Anand Padmanabhan
- Divisions of Hematopathology, Transfusion Medicine, and Experimental Pathology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN (A.P.)
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Jousselme E, Guéry EA, Nougier C, Sobas F, Rollin J, Gruel Y, Vayne C, Pouplard C. Prospective evaluation of two specific IgG immunoassays (HemosIL ® AcuStar HIT-IgG and HAT45G ® ) for the diagnosis of heparin-induced thrombocytopenia: A Bayesian approach. Int J Lab Hematol 2020; 43:468-476. [PMID: 33244896 DOI: 10.1111/ijlh.13404] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 09/30/2020] [Accepted: 10/21/2020] [Indexed: 12/11/2022]
Abstract
INTRODUCTION The accurate diagnosis of heparin-induced thrombocytopenia (HIT) is essential to ensure adequate treatment and prevent complications. First step diagnosis test are immunoassays including enzyme-linked immunosorbent assays (ELISAs) and rapid immunoassays. METHODS Using a Bayesian approach, we prospectively evaluated the performance of the IgG PF4/polyvinylsulfonate ELISA and a chemiluminescent immunoassay (CLIA), which are specific for IgG and use the same antigenic target to detect HIT antibodies. RESULTS One hundred and eighty-four 184 consecutive patients with an intermediate (n = 159) or high (n = 25) clinical pretest probability of HIT based on the 4Ts score or platelet pattern were included. Both immunoassays (IAs) were performed on all 184 samples, and definite HIT was confirmed with a positive serotonin release assay in 29 patients (12.7%). The sensitivity (Ss) and negative predictive value (NPV) of ELISA were excellent (100%) allowing HIT to be excluded with good confidence when the test was negative. In addition, the Ss and NPV of the CLIA equalled 93.1% and 98.6%, respectively, as it was negative in two definite HIT. When the CLIA was negative, the post-test probability of HIT was 0.7% in case of intermediate risk. Although there was excellent agreement between CLIA and ELISA results, the quantitative values provided by the two IAs were not correlated. CONCLUSION AcuStar HIT® detects more than 90% of HIT, as do all rapid IAs, and appears to be a good tool for excluding HIT when the pretest probability is intermediate. A chemiluminescent signal higher than 10 IU/mL is highly predictive of definite HIT with a PPV of 100%.
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Affiliation(s)
- Emilie Jousselme
- Department of Haematology-Haemostasis, Civil Hospices of Lyon, Bron, France
| | - Eve-Anne Guéry
- Department of Haematology-Haemostasis, Regional University Hospital of Tours, Tours, France
| | - Christophe Nougier
- Department of Haematology-Haemostasis, Civil Hospices of Lyon, Bron, France
| | - Frédéric Sobas
- Department of Haematology-Haemostasis, Civil Hospices of Lyon, Bron, France
| | - Jérôme Rollin
- Department of Haematology-Haemostasis, Regional University Hospital of Tours, Tours, France.,EA 7501 GICC, University of Tours, Tours, France
| | - Yves Gruel
- Department of Haematology-Haemostasis, Regional University Hospital of Tours, Tours, France.,EA 7501 GICC, University of Tours, Tours, France
| | - Caroline Vayne
- Department of Haematology-Haemostasis, Regional University Hospital of Tours, Tours, France.,EA 7501 GICC, University of Tours, Tours, France
| | - Claire Pouplard
- Department of Haematology-Haemostasis, Regional University Hospital of Tours, Tours, France.,EA 7501 GICC, University of Tours, Tours, France
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Arepally GM, Cines DB. Pathogenesis of heparin-induced thrombocytopenia. Transl Res 2020; 225:131-140. [PMID: 32417430 PMCID: PMC7487042 DOI: 10.1016/j.trsl.2020.04.014] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 04/15/2020] [Accepted: 04/21/2020] [Indexed: 01/19/2023]
Abstract
There are currently no effective substitutes for high intensity therapy with unfractionated heparin (UFH) for cardiovascular procedures based on its rapid onset of action, ease of monitoring and reversibility. The continued use of UFH in these and other settings requires vigilance for its most serious nonhemorrhagic complication, heparin induced thrombocytopenia (HIT). HIT is an immune prothrombotic disorder caused by antibodies that recognize complexes between platelet factor 4 (PF4) and polyanions such as heparin (H).The pathogenicity of anti-PF4/H antibodies is likely due to the formation of immune complexes that initiate intense procoagulant responses by vascular and hematopoietic cells that lead to the generation of platelet microparticles, monocyte and endothelial cell procoagulant activity, and neutrophil extracellular traps, among other outcomes. The development of anti-PF4/H antibodies after exposure to UFH greatly exceeds the incidence of clinical disease, but the biochemical features that distinguish pathogenic from nonpathogenic antibodies have not been identified. Diagnosis relies on pretest clinical probability, screening for anti-PF4/H antibodies and documentation of their platelet activating capacity. However, both clinical algorithms and test modalities have limited predictive values making diagnosis and management challenging. Given the unacceptable rates of recurrent thromboembolism and bleeding associated with current therapies, there is an unmet need for novel rational nonanticoagulant therapeutics based on the pathogenesis of HIT. We will review recent developments in our understanding of the pathogenesis of HIT and its implications for future approaches to diagnosis and management.
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Affiliation(s)
- Gowthami M Arepally
- Division of Hematology, Duke University Medical Center, Durham, North Carolina.
| | - Douglas B Cines
- Department of Pathology and Laboratory Medicine, Perelman-University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
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Warkentin TE. Challenges in Detecting Clinically Relevant Heparin-Induced Thrombocytopenia Antibodies. Hamostaseologie 2020; 40:472-484. [PMID: 33091948 PMCID: PMC7581458 DOI: 10.1055/a-1223-3329] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Heparin-induced thrombocytopenia (HIT) is an antibody-mediated hypercoagulable state featuring high thrombosis risk and distinct pathogenesis involving immunoglobulin G-mediated platelet activation. The target of the immune response is a cationic “self” protein, platelet factor 4 (PF4), rendered antigenic by heparin. A key problem is that only a minority of anti-PF4/polyanion antibodies induced by heparin are pathogenic, i.e., capable of causing platelet activation and thereby clinical HIT. Since thrombocytopenia occurs frequently in hospitalized, heparin-treated patients, testing for “HIT antibodies” is common; thus, the problem of distinguishing between pathogenic and nonpathogenic antibodies is important. The central concept is that those antibodies that have platelet-activating properties demonstrable in vitro correlate well with pathogenicity, as shown by platelet activation tests such as the serotonin-release assay (SRA) and heparin-induced platelet activation assay. However, in most circumstances, immunoassays are used for first-line testing, and so it is important for clinicians to appreciate which immunoassay result profiles—in the appropriate clinical context—predict the presence of platelet-activating antibodies (Bayesian analysis). Clinicians with access to rapid, on-demand HIT immunoassays (e.g., particle gel immunoassay, latex immunoturbidimetric assay, chemiluminescent immunoassay) can look beyond simple dichotomous result interpretation (“negative”/“positive”) and incorporate semiquantitative interpretation, where, for example, a strong-positive immunoassay result (or even combination of two immunoassays) points to a greater probability of detecting platelet-activating antibodies, and hence supporting a diagnosis of HIT. Recent recognition of “SRA-negative HIT” has increased the importance of semiquantitative interpretation of immunoassays, given that strong immunoassay reactivity is a potential clue indicating possible HIT despite a (false) negative platelet activation assay.
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Affiliation(s)
- Theodore E Warkentin
- Department of Pathology and Molecular Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada.,Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada.,Transfusion Medicine, Hamilton Regional Laboratory Medicine Program, Hamilton, Ontario, Canada.,Service of Clinical Hematology, Hamilton Health Sciences, Hamilton General Hospital, Hamilton, Ontario, Canada.,McMaster Centre for Transfusion Research, Hamilton, Ontario, Canada
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Abstract
Purpose of Review This review will illustrate the importance of heparin-induced thrombocytopenia in the intraoperative and critical care settings. Recent Findings Heparin-induced thrombocytopenia (HIT) occurs more frequently in surgical patients compared with medical patients due to the inflammatory release of platelet factor 4 and perioperative heparin exposure. Recognition of this disease requires a high index of suspicion. Diagnostic tools and therapeutic strategies have been expanded and refined in recent years. Summary HIT is a condition where antibodies against the heparin/platelet factor 4 complex interact with platelet receptors to promote platelet activation, aggregation, and thrombus formation. Our review will focus on intraoperative and postoperative considerations related to HIT to help the clinician better manage this rare but often devastating hypercoagulable disease process.
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Warkentin TE, Nazy I, Sheppard JI, Smith JW, Kelton JG, Arnold DM. Serotonin-release assay-negative heparin-induced thrombocytopenia. Am J Hematol 2020; 95:38-47. [PMID: 31621093 DOI: 10.1002/ajh.25660] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 10/09/2019] [Accepted: 10/13/2019] [Indexed: 12/22/2022]
Abstract
Heparin-induced thrombocytopenia (HIT) is a prothrombotic drug reaction caused by platelet-activating anti-platelet factor 4 (PF4)/heparin antibodies. Pathogenic HIT antibodies can be detected by the serotonin-release assay (SRA), a platelet activation test. We have regarded the SRA performed in our medical community ("McMaster" SRA) as having high sensitivity and specificity. Recently, the concept of "SRA-negative HIT" has been proposed for enzyme-immunoassay (EIA)-positive/SRA-negative patients with a HIT-compatible clinical picture, who test positive in a PF4-enhanced platelet activation assay. After identifying an index case of SRA-negative HIT, we estimated the frequency of this condition by performing the "PF4-SRA" (modified SRA using high concentrations of added PF4 rather than heparin) in EIA-positive patients from a cohort study evaluating clinical and laboratory diagnosis of HIT. We defined SRA-negative HIT as patients meeting three criteria: clinical picture compatible with HIT (4Ts ≥ 4 points); EIA-positive (≥1.00 units); and PF4-SRA-positive. Among 430 patients, 35 were EIA-positive/SRA-positive and 27 were EIA-positive/SRA-negative. Among these 27 SRA-negative patients, three were found to have subthreshold levels of platelet-activating antibodies by PF4-SRA, of whom one met clinical criteria for SRA-negative HIT. Thus, based on identifying one patient with SRA-negative HIT within a cohort study that found 35 SRA-positive HIT patients, we estimate the sensitivity of the McMaster SRA for diagnosis of HIT to be 35/36 (97.2%; 95% CI, 85.8-99.9%). Although the McMaster SRA is highly sensitive for HIT, occasional SRA-negative but EIA-positive patients strongly suspected of having HIT can have this diagnosis supported by a PF4-enhanced activation assay such as the PF4-SRA.
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Affiliation(s)
- Theodore E. Warkentin
- Department of Pathology and Molecular MedicineMichael G. DeGroote School of Medicine Hamilton Ontario Canada
- Department of MedicineMichael G. DeGroote School of Medicine Hamilton Ontario Canada
- McMaster Centre for Transfusion Research Hamilton Ontario Canada
| | - Ishac Nazy
- Department of MedicineMichael G. DeGroote School of Medicine Hamilton Ontario Canada
- McMaster Centre for Transfusion Research Hamilton Ontario Canada
| | - Jo‐Ann I. Sheppard
- Department of Pathology and Molecular MedicineMichael G. DeGroote School of Medicine Hamilton Ontario Canada
| | - James W. Smith
- Department of MedicineMichael G. DeGroote School of Medicine Hamilton Ontario Canada
| | - John G. Kelton
- Department of MedicineMichael G. DeGroote School of Medicine Hamilton Ontario Canada
- McMaster Centre for Transfusion Research Hamilton Ontario Canada
| | - Donald M. Arnold
- Department of MedicineMichael G. DeGroote School of Medicine Hamilton Ontario Canada
- McMaster Centre for Transfusion Research Hamilton Ontario Canada
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Pishko AM, Lefler DS, Gimotty P, Paydary K, Fardin S, Arepally GM, Crowther M, Rice L, Vega R, Cines DB, Guevara JP, Cuker A. The risk of major bleeding in patients with suspected heparin-induced thrombocytopenia. J Thromb Haemost 2019; 17:1956-1965. [PMID: 31350937 PMCID: PMC6913895 DOI: 10.1111/jth.14587] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Accepted: 07/22/2019] [Indexed: 01/19/2023]
Abstract
BACKGROUND The presence of a hypercoagulable disorder such as heparin-induced thrombocytopenia (HIT) may protect against anticoagulant-associated bleeding. OBJECTIVES To determine the incidence of major bleeding in patients with suspected HIT. METHODS We performed a retrospective analysis of 310 patients suspected of having HIT from the Hospital of the University of Pennsylvania and an affiliated community hospital. We compared the cumulative incidence of major bleeding following suspicion for HIT by ultimate HIT status (HIT+ or HIT-) and exposure to an alternative anticoagulant (Tx+ or Tx-). Secondary outcomes included the incidence of new/progressive thrombosis and 30-day mortality. RESULTS The incidence of major bleeding was high in the HIT+Tx+, HIT- Tx+, and HIT-Tx- groups (35.7%, 44.0%, and 37.3%, respectively). The time to first major bleeding event did not differ between groups (P = .24). Factors associated with increased risk of major bleeding included intensive care unit admission (HR 2.24, 95% CI 1.44-3.47), platelet count < 25 × 109 /L (HR 2.13, 1.10-4.12), and renal dysfunction (HR 1.56, 1.06-2.27); 35.7% of HIT+Tx+, 13.8% HIT-Tx+, and 9.3% of HIT-Tx- patients experienced new or progressive thrombosis. Mortality was similar among the three groups (26.2% HIT+Tx+, 34.5% HIT-Tx+, and 26.7% of HIT-Tx- [P = .34]). CONCLUSIONS Among patients with suspected HIT, major bleeding was common regardless of HIT status. Contrary to our hypothesis, HIT+ patients were not protected from major bleeding. A better understanding of bleeding risk is needed to inform management decisions in patients with suspected HIT.
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Affiliation(s)
- Allyson M Pishko
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Daniel S Lefler
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Phyllis Gimotty
- Department of Biostatistics and Epidemiology and Informatics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Koosha Paydary
- Department of Internal Medicine, John H. Stroger Jr. Hospital of Cook County, Chicago, Illinois
| | - Sara Fardin
- Department of Radiology, Tufts Medical Center, Boston, Massachusetts
| | - Gowthami M Arepally
- Division of Hematology, Department of Medicine, Duke University, Durham, North Carolina
| | - Mark Crowther
- Department of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Lawrence Rice
- Hematology Division, Department of Medicine, Houston Methodist Hospital, Weill Cornell Medical College, Houston, Texas
| | - Rolando Vega
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Douglas B Cines
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - James P Guevara
- Department of Biostatistics and Epidemiology and Informatics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
- Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Adam Cuker
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
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Samuel S, McGuire MF, Cortes J, Escobar M, Weeks P, Nguyen A. Comparison of polyspecific versus IgG specific ELISA in predominately cardiac patients with suspected heparin induced thrombocytopenia. J Thromb Thrombolysis 2019; 49:27-33. [PMID: 31552545 DOI: 10.1007/s11239-019-01957-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
A diagnosis of heparin induced thrombocytopenia (HIT) must often be made based on clinical and laboratory evidence. This was a quasi-experimental study of patients admitted from June 2016 to October 2017. The primary endpoint was the incidence of false positive results in polyspecific and IgG specific enzyme-linked immunosorbent assay (ELISA); then we compared the sensitivity and specificity of each assays in predominately cardiac patients with suspected HIT. A sensitivity/specificity analysis was conducted using serotonin release assay (SRA) as the 'gold standard'. The secondary outcome measures included length of hospital stay. We identified a total of 155 patients who met the inclusion criteria. Confirmatory tests with SRA on both groups were completed; false positive result was higher in the polyspecific group when compared to the IgG group [60% vs. 5%]. The IgG specific ELISA test yielded a sensitivity of 100% and a specificity of 95% however, the polyspecific ELISA had a low yield for specificity of 24% but maintained 100% sensitivity. In the IgG specific group with HIT-, their median length of stay was halved compared to those who were HIT + ; hospital LOS in days, IQR [30 (27-81) vs. 15 (7-33) p = 0.023] and a shorter median LOS in the ICU, IQR [24 (5-47) vs. 6 (2-14); p = 0.079]. Hospital or ICU LOS was the same in both (HIT+ and HIT-) groups managed with polyspecific ELISA. The IgG specific test had few false positive results and a high sensitivity score. Ensuring appropriate testing can bring a substantial decrease in drug expenditure, reduced length of stay and prevent unnecessary anticoagulation.
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Affiliation(s)
- Sophie Samuel
- Department of Pharmacy, Neuroscience Intensive Care Unit, Memorial Hermann - Texas Medical Center, 6411 Fannin Street, Houston, TX, 77030, USA.
| | - Mary F McGuire
- Department of Neurosurgery and Neurology, The University of Texas McGovern Medical School, Houston, TX, USA
| | - Jennifer Cortes
- Department of Pharmacy, Medical Intensive Care Unit, Memorial Hermann - Texas Medical Center, Houston, TX, USA
| | - Miguel Escobar
- Department of Hematology, The University of Texas McGovern Medical School, Houston, TX, USA
| | - Phillip Weeks
- Department of Pharmacy, Heart and Vascular Institute, Memorial Hermann - Texas Medical Center, Houston, TX, USA
| | - Andy Nguyen
- Department of Pathology and Laboratory Medicine, The University of Texas McGovern Medical School, Houston, TX, USA
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Prospective comparison of the HEP score and 4Ts score for the diagnosis of heparin-induced thrombocytopenia. Blood Adv 2019; 2:3155-3162. [PMID: 30463915 DOI: 10.1182/bloodadvances.2018023077] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 10/23/2018] [Indexed: 12/31/2022] Open
Abstract
The HIT Expert Probability (HEP) score compared favorably with the 4Ts score in a retrospective study. We assessed the diagnostic accuracy of the HEP score compared with the 4Ts score in a prospective cohort of 310 patients with suspected heparin-induced thrombocytopenia (HIT). A member of the clinical team calculated the HEP score and 4Ts score. An independent panel adjudicated HIT status based on a clinical summary as well as the results of HIT laboratory testing. The prevalence of HIT in the study population was 14.7%. At a cutoff of ≥3, the HEP score was 95.3% sensitive (95% confidence interval [CI], 84.2-99.4) and 35.7% specific (95% CI, 29.8-42.0) for HIT. A 4Ts score of ≥4 had a sensitivity of 97.7% (95% CI, 86.2-99.8) and specificity of 32.9% (95% CI, 27.2-39.1). The areas under the receiver operating characteristic (ROC) curves (AUCs) for the HEP score and 4Ts score were similar (0.81 [95% CI, 0.74-0.87] vs 0.76 [95% CI, 0.69-0.83]; P = .12). The HEP score exhibited a significantly higher AUC than the 4Ts score in patients in the intensive care unit (ICU) (0.86 vs 0.79; P = .03). Among trainee scorers, the HEP score performed significantly better than the 4Ts score (AUC, 0.80 vs 0.73; P = .03). Our data suggest that either the 4Ts score or the HEP score may be used in clinical practice. The HEP score may be preferable in ICU patients and among less experienced clinicians.
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Warkentin TE, Sheppard JI, Smith JW, Arnold DM, Nazy I. Timeline of heparin-induced thrombocytopenia seroconversion in serial plasma samples tested using an automated latex immunoturbidimetric assay. Int J Lab Hematol 2019; 41:493-502. [PMID: 31050876 PMCID: PMC6850468 DOI: 10.1111/ijlh.13031] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 03/22/2019] [Accepted: 03/23/2019] [Indexed: 01/22/2023]
Abstract
INTRODUCTION HIT is caused by platelet-activating IgG that recognize multimolecular PF4/heparin complexes. HIT antibodies are generally detectable by PF4-dependent enzyme immunoassay (EIA) and by platelet serotonin-release assay (SRA) at the beginning of the HIT-related platelet count fall. We determined whether an automated immunoassay for HIT, the latex immunoturbidimetric assay (LIA), also detects antibodies early during the course of HIT. The LIA was also used to evaluate a patient with putative SRA-negative HIT. METHODS We evaluated the timing and magnitude of LIA reactivity in serial plasma samples obtained from 19 SRA-positive patients (17 with abnormal platelet count changes indicating HIT; two with subclinical seroconversion) and one putative SRA-negative HIT patient, all obtained from patients who participated in a clinical trial of heparin thromboprophylaxis. We determined LIA status at the onset of the HIT-related platelet count fall. RESULTS The LIA was positive in all 19 SRA-positive patients (median value, 7.3 U/mL [range, 1.2-35.5]; cutoff, 1.0 U/mL); for all 13 evaluable patients for whom an informative plasma sample was available at (or shortly before) the onset of the HIT-related platelet count fall, LIA reactivity was positive. Heterogeneity in seroconversion using the LIA was observed; some patients exhibited gradual increases in reactivity, whereas other patients showed rapid increase in reactivity over a few days. The single clinical trial patient who met clinical-pathological criteria for "SRA-negative HIT" tested LIA-positive. CONCLUSION The LIA detects HIT antibodies at the beginning of the HIT-associated platelet count fall. The LIA was also positive in a patient with SRA-negative HIT.
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Affiliation(s)
- Theodore E. Warkentin
- Department of Pathology and Molecular Medicine, Michael G. DeGroote School of MedicineMcMaster UniversityHamiltonOntarioCanada
- Department of Medicine, Michael G. DeGroote School of MedicineMcMaster UniversityHamiltonOntarioCanada
- McMaster Centre for Transfusion ResearchHamiltonOntarioCanada
- Hamilton Regional Laboratory Medicine ProgramHamilton Health SciencesHamiltonOntarioCanada
| | - Jo‐Ann I. Sheppard
- Department of Pathology and Molecular Medicine, Michael G. DeGroote School of MedicineMcMaster UniversityHamiltonOntarioCanada
| | - James W. Smith
- Department of Medicine, Michael G. DeGroote School of MedicineMcMaster UniversityHamiltonOntarioCanada
| | - Donald M. Arnold
- Department of Medicine, Michael G. DeGroote School of MedicineMcMaster UniversityHamiltonOntarioCanada
- McMaster Centre for Transfusion ResearchHamiltonOntarioCanada
| | - Ishac Nazy
- Department of Medicine, Michael G. DeGroote School of MedicineMcMaster UniversityHamiltonOntarioCanada
- McMaster Centre for Transfusion ResearchHamiltonOntarioCanada
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Warkentin TE. Laboratory diagnosis of heparin-induced thrombocytopenia. Int J Lab Hematol 2019; 41 Suppl 1:15-25. [PMID: 31069988 DOI: 10.1111/ijlh.12993] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 01/25/2019] [Accepted: 02/01/2019] [Indexed: 12/18/2022]
Abstract
Heparin-induced thrombocytopenia (HIT) is a clinical-pathological disorder; thus, laboratory testing for the pathogenic platelet-activating antiplatelet factor 4 (PF4)/heparin antibodies is central for diagnosis. The "iceberg" model summarizes the inter-relationship between platelet activation assays and PF4-dependent immunoassays, with platelet-activating antibodies comprising a subset of anti-PF4/heparin antibodies. The platelet serotonin-release assay (SRA), performed by reference laboratories, has high sensitivity and specificity for HIT (~95% each), and is especially suited for detecting highly pathogenic HIT sera containing both heparin-dependent and heparin-independent platelet-activating antibodies; this latter subgroup of antibodies explains "autoimmune HIT" disorders (delayed-onset, persisting, spontaneous, heparin "flush," fondaparinux-associated). Recently, SRA-negative HIT has become recognized, in which serum from some HIT patients contains subthreshold levels of platelet-activating antibodies (by SRA) that become detectable using a PF4-enhanced platelet activation assay. Unusual immunologic features of HIT include early antibody detectability (at onset of platelet count fall) and antibody transience (seroreversion). Widely available PF4-dependent enzyme immunoassays (EIAs) have high sensitivity but poor specificity for HIT, although specificity is enhanced with IgG-specific EIAs and strong positive results; unfortunately, EIA results are usually not available in real time. Automated rapid immunoassays, such as the chemiluminescence immunoassay (CLIA) and latex immunoturbidimetric assay (LIA), facilitate real-time laboratory diagnosis. Recently available likelihood ratio (LR) data for positive (LR+) and negative (LR-) test results allow clinicians to adjust their pretest probabilities for HIT, using Bayesian analysis, into real-time posttest probabilities that are dramatically increased (test positive) or decreased (test negative). Moreover, (semi-)quantitative CLIA- and LIA-positive results (weak, moderate, strong positive) can further refine the posttest probability of HIT.
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Affiliation(s)
- Theodore E Warkentin
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada.,Department of Pathology and Molecular Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada.,Hamilton Regional Laboratory Medicine Program, Hamilton Health Sciences, Hamilton General Hospital, Hamilton, Ontario, Canada.,McMaster Centre for Transfusion Research, Hamilton, Ontario, Canada
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Choi JH, Luc JGY, Weber MP, Reddy HG, Maynes EJ, Deb AK, Samuels LE, Morris RJ, Massey HT, Loforte A, Tchantchaleishvili V. Heparin-induced thrombocytopenia during extracorporeal life support: incidence, management and outcomes. Ann Cardiothorac Surg 2019; 8:19-31. [PMID: 30854309 DOI: 10.21037/acs.2018.12.02] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Background Heparin-induced thrombocytopenia (HIT) is a severe antibody-mediated reaction leading to transient prothrombosis. However, its incidence in patients on extracorporeal life support (ECLS) is not well described. The aim of this systematic review was to report the incidence of HIT in patients on ECLS, as well as compare the characteristics and outcomes of HIT in patients undergoing veno-arterial extracorporeal membrane oxygenation (VA-ECMO) and veno-venous ECMO (VV-ECMO). Methods An electronic search was performed to identify all studies in the English literature examining outcomes of patients with HIT on ECLS. All identified articles were systematically assessed using specific inclusion and exclusion criteria. Random effects meta-analysis as well as univariate analysis was performed. Results Of 309 patients from six retrospective studies undergoing ECLS, 83% were suspected, and 17% were confirmed to have HIT. Due to the sparsity of relevant retrospective data regarding patients with confirmed HIT on ECLS, patient-based data was subsequently collected on 28 patients from case reports and case series. Out of these 28 patients, 53.6% and 46.4% of them underwent VA-ECMO and VV-ECMO, respectively. Patients on VA-ECMO had a lower median platelet count nadir (VA-ECMO: 26.0 vs. VV-ECMO: 45.0 per µL, P=0.012) and were more likely to experience arterial thromboembolism (VA-ECMO: 53.3% vs. VV-ECMO: 0.0%, P=0.007), though there was a trend towards decreased likelihood of experiencing ECLS circuit oxygenator thromboembolism (VA-ECMO: 0.0% vs. VV-ECMO: 30.8%, P=0.075) and thromboembolism necessitating ECLS device or circuit exchange (VA-ECMO: 13.3% vs. VV-ECMO 53.8%, P=0.060). Kaplan-Meier survival plots including time from ECLS initiation reveal no significant differences in survival in patients supported on VA-ECMO as compared to VV-ECMO (P=0.300). Conclusions Patients who develop HIT on VA-ECMO are more likely to experience more severe thrombocytopenia and arterial thromboembolism than those on VV-ECMO. Further research in this area and development of standardized protocols for the monitoring, diagnosis and management of HIT in patients on ECLS support are warranted.
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Affiliation(s)
- Jae Hwan Choi
- Division of Cardiac Surgery, Thomas Jefferson University, Philadelphia, PA, USA
| | - Jessica G Y Luc
- Division of Cardiovascular Surgery, Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada
| | - Matthew P Weber
- Division of Cardiac Surgery, Thomas Jefferson University, Philadelphia, PA, USA
| | - Haritha G Reddy
- Division of Cardiac Surgery, Thomas Jefferson University, Philadelphia, PA, USA
| | - Elizabeth J Maynes
- Division of Cardiac Surgery, Thomas Jefferson University, Philadelphia, PA, USA
| | - Avijit K Deb
- Philadelphia College of Osteopathic Medicine, Philadelphia, PA, USA
| | - Louis E Samuels
- Division of Cardiac Surgery, Thomas Jefferson University, Philadelphia, PA, USA
| | - Rohinton J Morris
- Division of Cardiac Surgery, Thomas Jefferson University, Philadelphia, PA, USA
| | - H Todd Massey
- Division of Cardiac Surgery, Thomas Jefferson University, Philadelphia, PA, USA
| | - Antonio Loforte
- Department of Cardiovascular Surgery and Transplantation, S. Orsola-Malpighi Hospital, University of Bologna, Bologna, Italy
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24
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High sensitivity and specificity of an automated IgG-specific chemiluminescence immunoassay for diagnosis of HIT. Blood 2018; 132:1345-1349. [PMID: 30064975 DOI: 10.1182/blood-2018-04-847483] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
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25
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Platelet-Activating Antibodies Are Detectable at the Earliest Onset of Heparin-Induced Thrombocytopenia, With Implications for the Operating Characteristics of the Serotonin-Release Assay. Chest 2018; 153:1396-1404. [DOI: 10.1016/j.chest.2018.01.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Revised: 12/01/2017] [Accepted: 01/02/2018] [Indexed: 11/21/2022] Open
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26
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Vayne C, Guery EA, Kizlik-Masson C, Rollin J, Bauters A, Gruel Y, Pouplard C. Beneficial effect of exogenous platelet factor 4 for detecting pathogenic heparin-induced thrombocytopenia antibodies. Br J Haematol 2017; 179:811-819. [DOI: 10.1111/bjh.14955] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Accepted: 08/09/2017] [Indexed: 12/17/2022]
Affiliation(s)
- Caroline Vayne
- Department of Haematology-Haemostasis; University Hospital of Tours; Tours France
- University François Rabelais; UMR CNRS 7292; Tours France
| | - Eve-Anne Guery
- Department of Haematology-Haemostasis; University Hospital of Tours; Tours France
- University François Rabelais; UMR CNRS 7292; Tours France
| | | | - Jérôme Rollin
- Department of Haematology-Haemostasis; University Hospital of Tours; Tours France
- University François Rabelais; UMR CNRS 7292; Tours France
| | - Anne Bauters
- Institute of Haematology-Transfusion; University Hospital of Lille; Lille France
| | - Yves Gruel
- Department of Haematology-Haemostasis; University Hospital of Tours; Tours France
- University François Rabelais; UMR CNRS 7292; Tours France
| | - Claire Pouplard
- Department of Haematology-Haemostasis; University Hospital of Tours; Tours France
- University François Rabelais; UMR CNRS 7292; Tours France
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