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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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Bissola AL, Daka M, Ivetic N, Clare R, Pai M, Kelton JG, Arnold DM, Nazy I. Evaluation of laboratory testing parameters for vaccine-induced immune thrombotic thrombocytopenia and their implications for diagnosis. J Thromb Haemost 2024; 22:304-306. [PMID: 37866513 DOI: 10.1016/j.jtha.2023.10.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 10/06/2023] [Accepted: 10/09/2023] [Indexed: 10/24/2023]
Affiliation(s)
- Anna-Lise Bissola
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Mercy Daka
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Nikola Ivetic
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Rumi Clare
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Menaka Pai
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - John G Kelton
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada; Department of Medicine, Michael G. DeGroote Centre for Transfusion Research, McMaster University, Hamilton, Ontario, Canada
| | - Donald M Arnold
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada; Department of Medicine, 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; Department of Medicine, Michael G. DeGroote Centre for Transfusion Research, McMaster University, Hamilton, Ontario, Canada; Department of Biochemistry and Biomedical Sciences, McMaster University Hamilton, Hamilton, Ontario, Canada.
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3
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Cogan JC, McFarland MM, May JE, Lim MY. Quality improvement approaches to heparin-induced thrombocytopenia: a scoping review. Res Pract Thromb Haemost 2023; 7:102219. [PMID: 38077807 PMCID: PMC10704520 DOI: 10.1016/j.rpth.2023.102219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 09/18/2023] [Accepted: 09/21/2023] [Indexed: 02/12/2024] Open
Abstract
Background Heparin-induced thrombocytopenia (HIT) is a relatively uncommon condition characterized by 2 exceedingly common phenomena in hospitalized patients: thrombocytopenia and heparin exposure. Consequently, HIT is frequently overdiagnosed and inappropriately treated. These issues are the focus of many quality improvement (QI) initiatives. Objectives In this scoping review, we identified and characterized all published QI studies on improving the diagnosis and management of HIT. Methods We conducted a systematic literature search through April 2022 for studies reporting on QI interventions regarding the diagnosis, treatment, and/or prevention of HIT. Results Thirty studies were included in the final review. Studies were separated into 5 groups based on the focus of the interventions: increasing HIT recognition, reducing HIT incidence, reducing HIT overdiagnosis, promoting safer HIT management, and creating HIT task forces. Nine studies focused on the implementation of 4Ts score calculator into electronic medical record orders for HIT testing, while only 1 evaluated the impact of reducing unfractionated heparin use in favor of low-molecular-weight heparin. Six studies focused on the implementation of direct thrombin inhibitor management protocols, while none evaluated the use of alternative anticoagulants in HIT management. Conclusion The bulk of published HIT QI research focused on reducing overdiagnosis and promoting safer direct thrombin inhibitor therapy, while minimal attention has been devoted to HIT prevention and the use of evidence-based alternative HIT therapies.
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Affiliation(s)
- Jacob C. Cogan
- Division of Hematology, Oncology and Transplantation, University of Minnesota, Minneapolis, Minnesota, USA
| | - Mary M. McFarland
- Spencer S. Eccles Health Sciences Library, University of Utah, Salt Lake City, Utah, USA
| | - Jori E. May
- University of Alabama at Birmingham Medicine Birmingham, Alabama, USA
| | - Ming Y. Lim
- Division of Hematology and Hematologic Malignancies, Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA
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Venier LM, Clerici B, Bissola AL, Modi D, Jevtic SD, Radford M, Mahamad S, Nazy I, Arnold DM. Unique features of vaccine-induced immune thrombotic thrombocytopenia; a new anti-platelet factor 4 antibody-mediated disorder. Int J Hematol 2023; 117:341-348. [PMID: 36574172 PMCID: PMC9793819 DOI: 10.1007/s12185-022-03516-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 12/02/2022] [Accepted: 12/12/2022] [Indexed: 12/29/2022]
Abstract
Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a highly prothrombotic disorder caused by anti-PF4 antibodies that activate platelets and neutrophils, leading to thrombosis. Heparin-induced thrombocytopenia (HIT) is a related anti-PF4 mediated disorder, with similar pathophysiology and clinical manifestations but different triggers (i.e., heparin vs adenoviral vector vaccine). Clinically, both HIT and VITT typically present with thrombocytopenia and thrombosis, although the risk of thrombosis is significantly higher in VITT, and the thromboses occur in unusual anatomical sites (e.g., cerebral venous sinus thrombosis and hepatic vein thrombosis). The diagnostic accuracy of available laboratory testing differs between HIT and VITT; for VITT, ELISAs have better specificity compared to HIT and platelet activation assays require the addition of PF4. Treatment of VITT and HIT is anticoagulation non-heparin anticoagulants; however, heparin may be considered for VITT if no other option is available.
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Affiliation(s)
- Laura M. Venier
- Faculty of Health Sciences, McMaster University, Hamilton, ON Canada
| | - Bianca Clerici
- Divisione di Medicina Generale II, ASST Santi Paolo e Carlo, Dipartimento di Scienze della Salute, Università degli Studi di Milano, Milan, Italy ,McMaster Centre for Transfusion Research, McMaster University, 1280 Main Street West, Room HSC 3H50, Hamilton, ON L8S 4K1 Canada
| | - Anna-Lise Bissola
- Department of Medicine, Michael G. DeGroote School of Medicine, Hamilton, ON Canada ,Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON Canada
| | - Dimpy Modi
- McMaster Centre for Transfusion Research, McMaster University, 1280 Main Street West, Room HSC 3H50, Hamilton, ON L8S 4K1 Canada
| | - Stefan D. Jevtic
- Department of Medicine, Michael G. DeGroote School of Medicine, Hamilton, ON Canada
| | - Michael Radford
- Department of Medicine, Michael G. DeGroote School of Medicine, Hamilton, ON Canada
| | - Syed Mahamad
- McMaster Centre for Transfusion Research, McMaster University, 1280 Main Street West, Room HSC 3H50, Hamilton, ON L8S 4K1 Canada
| | - Ishac Nazy
- Department of Medicine, Michael G. DeGroote School of Medicine, Hamilton, ON Canada ,McMaster Centre for Transfusion Research, McMaster University, 1280 Main Street West, Room HSC 3H50, Hamilton, ON L8S 4K1 Canada
| | - Donald M. Arnold
- Department of Medicine, Michael G. DeGroote School of Medicine, Hamilton, ON Canada ,McMaster Centre for Transfusion Research, McMaster University, 1280 Main Street West, Room HSC 3H50, Hamilton, ON L8S 4K1 Canada
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Lee CSM, Powell MC, Chen VM. Whole Blood Procoagulant Platelet Flow Cytometry Protocol for Heparin-Induced Thrombocytopenia (HIT) and Vaccine-Induced Immune Thrombotic Thrombocytopenia (VITT) Testing. Methods Mol Biol 2023; 2663:441-461. [PMID: 37204729 DOI: 10.1007/978-1-0716-3175-1_29] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Heparin-induced thrombocytopenia (HIT) is a well-characterized, iatrogenic complication of heparin anticoagulation with significant morbidity. In contrast, vaccine-induced immune thrombotic thrombocytopenia (VITT) is a recently recognized severe prothrombotic complication of adenoviral vaccines, including the ChAdOx1 nCoV-19 (Vaxzevria, AstraZeneca) and Ad26.COV2.S (Janssen, Johnson & Johnson) vaccines against COVID-19. The diagnosis of HIT and VITT involve laboratory testing for antiplatelet antibodies by immunoassays followed by confirmation by functional assays to detect platelet-activating antibodies. Functional assays are critical to detect pathological antibodies due to the varying sensitivity and specificity of immunoassays. This chapter presents a protocol for a novel whole blood flow cytometry-based assay to detect procoagulant platelets in healthy donor blood in response to plasma from patients suspected of HIT or VITT. A method to identify suitable healthy donors for HIT and VITT testing is also described.
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Affiliation(s)
- Christine S M Lee
- ANZAC Research Institute, University of Sydney, Sydney, NSW, Australia
| | - Matthew C Powell
- Diagnostic Pathology Unit, NSW Health Pathology, Concord Hospital, Concord, NSW, Australia
| | - Vivien M Chen
- ANZAC Research Institute, University of Sydney, Sydney, NSW, Australia.
- Department of Haematology, Concord Hospital, Sydney Local Health District, Concord, NSW, Australia.
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The clinical and laboratory diagnosis of vaccine-induced immune thrombotic thrombocytopenia. Blood Adv 2022; 6:4228-4235. [PMID: 35609563 PMCID: PMC9132380 DOI: 10.1182/bloodadvances.2022007766] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Accepted: 05/16/2022] [Indexed: 11/20/2022] Open
Abstract
Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a rare but serious adverse syndrome occurring 5-30 days after adenoviral vector COVID-19 vaccination. Therefore, a practical evaluation of clinical assessments and laboratory testing for VITT is needed to prevent significant adverse outcomes as the global use of adenoviral vector vaccines continues. We received the clinical information and blood samples of 156 patient samples with a suspected diagnosis of VITT between April to July 2021 in Canada. The performance characteristics of various diagnostic laboratory tests were evaluated against the PF4-SRA including a commercial anti-PF4/heparin IgG/A/M enzyme immunoassay (EIA, PF4 Enhanced; Immucor), in-house IgG-specific anti-PF4 and anti-PF4/heparin-EIAs, the standard SRA, and the PF4/heparin-SRA. Of those, 43 (27.6%) had serologically confirmed VITT based on a positive PF4-SRA result and 113 (72.4%) were negative. The commercial anti-PF4/heparin EIA, the in-house anti-PF4-EIA, and anti-PF4/heparin-EIA were positive for all 43 VITT-confirmed samples (100% sensitivity) with a few false-positive results (mean specificity 95.6%). These immunoassays had specificities of 95.6% [95% confidence interval (CI) 90.0-98.6], 96.5% (95% CI 91.2-99.0), and 97.4% (95% CI 92.4-99.5), respectively. Functional tests, including the standard SRA and PF4/heparin-SRA, had high specificities (100%), but poor sensitivities for VITT [16.7% (95% CI 7.0-31.4); and 46.2% (95% CI 26.6-66.6), respectively]. These findings suggest EIA assays that can directly detect antibodies to PF4 or PF4/heparin have excellent performance characteristics and may be useful as a diagnostic test if the PF4-SRA is unavailable.
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Brodard J, Kremer Hovinga JA, Fontana P, Studt JD, Gruel Y, Greinacher A. COVID-19 patients often show high-titer non-platelet-activating anti-PF4/heparin IgG antibodies. J Thromb Haemost 2021; 19:1294-1298. [PMID: 33550713 PMCID: PMC8013750 DOI: 10.1111/jth.15262] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 02/02/2021] [Accepted: 02/03/2021] [Indexed: 01/17/2023]
Abstract
BACKGROUND Heparin-induced thrombocytopenia (HIT) is a severe adverse reaction to heparin caused by heparin-dependent, platelet-activating anti-platelet factor 4 (PF4)/heparin antibodies. Heparin is a cornerstone of treatment in critically ill COVID-19 patients. HIT antibodies can be detected by antigen tests and functional tests. Often strong reactivity in the antigen test is used as a surrogate marker for the presence of clinically relevant, platelet-activating antibodies. We observed an unexpectedly high percentage of COVID-19 patients, clinically suspected to have HIT, with high titer anti-PF4/heparin antibodies, but a negative functional test. OBJECTIVE We investigated whether in COVID-19 patients a serum-derived factor inhibits the heparin-induced platelet activation test (HIPA). METHODS AND RESULTS Twelve COVID-19 patients with suspected HIT were tested. Three samples tested negative in all assays; nine samples tested positive by antigen tests, among which only three tested also positive by HIPA. When we spiked COVID-19 serum or control serum with the human HIT antibody like monoclonal antibody 5B9, reactivity of 5B9 remained the same. Also, the purified IgG fractions of COVID-19 sera testing strongly positive in the PF4/heparin antigen test but negative in the functional test did not show increased reactivity in the functional test in comparison to the original serum. Both results make a functionally inhibitory factor in the serum/plasma of COVID-19 patients highly unlikely. CONCLUSION COVID-19 patients often present with strong reactivity in PF4/heparin antigen tests without the presence of platelet-activating antibodies. Diagnosis of HIT requires confirmation of heparin-dependent, platelets activating antibodies to avoid overdiagnosis and overtreatment with non-heparin anticoagulants.
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Affiliation(s)
- Justine Brodard
- Department of Hematology and Central Hematology Laboratory, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Johanna A Kremer Hovinga
- Department of Hematology and Central Hematology Laboratory, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Pierre Fontana
- Division of Angiology and Haemostasis, University Hospitals of Geneva, Geneva, Switzerland
| | - Jan-Dirk Studt
- Department of Medical Oncology and Hematology, University Hospital Zürich, Zürich, Switzerland
| | - Yves Gruel
- Department of Hematology-Hemostasis, University Hospital of Tours, Tours, France
| | - Andreas Greinacher
- Institut für Immunologie und Transfusionsmedizin, Universitätsmedizin Greifswald, Greifswald, Germany
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Zaydman MA, Brestoff JR, Jackups R. Using information theory to optimize a diagnostic threshold to match physician-ordering practice. J Biomed Inform 2021; 117:103756. [PMID: 33766781 DOI: 10.1016/j.jbi.2021.103756] [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: 10/13/2020] [Revised: 03/12/2021] [Accepted: 03/13/2021] [Indexed: 10/21/2022]
Abstract
OBJECTIVE Clinicians order laboratory tests in an effort to reduce diagnostic or therapeutic uncertainty. Information theory provides the opportunity to quantify the degree to which a test result is expected to reduce diagnostic uncertainty. We sought to apply information theory toward the evaluation and optimization of a diagnostic test threshold and to determine if the results would differ from those of conventional methodologies. We used a heparin/PF4 immunoassay (PF4 ELISA) as a case study. MATERIALS AND METHODS The laboratory database was queried for PF4 ELISA and serotonin release assay (SRA) results during the study period, with the latter serving as the gold standard for the disease heparin-induced thrombocytopenia (HIT). The optimized diagnostic threshold of the PF4 ELISA test was compared using conventional versus information theoretic approaches under idealized (pretest probability = 50%) and realistic (pretest probability = 2.4%) testing conditions. RESULTS Under ideal testing conditions, both analyses yielded a similar optimized optical density (OD) threshold of OD > 0.79. Under realistic testing conditions, information theory suggested a higher threshold, OD > 1.5 versus OD > 0.6. Increasing the diagnostic threshold improved the global information value, the value of a positive test and the noise content with only a minute change in the negative test value. DISCUSSION Our information theoretic approach suggested that the current FDA approved cutoff (OD > 0.4) is overly permissive leading to loss of test value and injection of noise into an already complex diagnostic dilemma. Because our approach is purely statistical and takes as input data that are readily accessible in the clinical laboratory it offers a scalable and data-driven strategy for optimizing test value that may be widely applicable in the domain of laboratory medicine. CONCLUSION Information theory provides more meaningful measures of test value than the widely used accuracy-based metrics.
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Affiliation(s)
- Mark A Zaydman
- Department of Pathology and Immunology, Washington University School of Medicine, St Louis, MO, USA.
| | - Jonathan R Brestoff
- Department of Pathology and Immunology, Washington University School of Medicine, St Louis, MO, USA
| | - Ronald Jackups
- Department of Pathology and Immunology, Washington University School of Medicine, St Louis, MO, USA
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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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Catalano MA, Prasad V, Spring AM, Cassiere H, Chang TY, Hartman A, Yu PJ. Heparin-induced thrombocytopenia in patients readmitted after open cardiac surgical procedures: A case series. JTCVS OPEN 2020; 4:36-42. [PMID: 36004296 PMCID: PMC9390529 DOI: 10.1016/j.xjon.2020.07.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 07/29/2020] [Accepted: 07/29/2020] [Indexed: 12/12/2022]
Abstract
Objectives Heparin-induced thrombocytopenia (HIT) is an immune-mediated complication that occurs in a small percentage of patients exposed to heparin. Concerns of HIT are particularly high in patients undergoing cardiac procedures requiring cardiopulmonary bypass, as they are exposed to high doses of heparin intraoperatively. Our aim was to identify and assess the hospital courses of patients who were diagnosed with HIT during readmission following cardiac surgery. Methods A retrospective review of patients who underwent open cardiac surgical procedures from June 2017 through October 2019 was performed. Of these, we identified patients who were newly diagnosed with HIT upon readmission. HIT positivity was defined as a positive anti-PF4 antibody screening test, plus a positive serotonin release assay. Results Of the 2496 patients identified, 13 patients were HIT positive on index admission and were excluded. Of the remaining 2483 patients, 351 were readmitted within 30 days. Six were newly diagnosed with HIT during readmission, 5 of whom presented with thrombotic complications. One patient was readmitted with thrombocytopenia and was started on argatroban; the remaining 5 did not have a significantly lower platelet count on readmission. Of the 12 patients readmitted for venous thromboembolism, 4 tested positive for HIT. Conclusions HIT can have a delayed appearance following open heart surgery. Venous thromboembolism appears to be a significant indicator for HIT during readmission, even in the absence of thrombocytopenia. This may support the use of non-heparin anticoagulation for cardiac surgery patients readmitted with thromboembolism until HIT status is determined.
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Affiliation(s)
- Michael A. Catalano
- Division of Cardiovascular and Thoracic Surgery, Zucker School of Medicine at Hofstra/Northwell, Manhasset, NY
| | - Vikram Prasad
- Division of Cardiovascular and Thoracic Surgery, Zucker School of Medicine at Hofstra/Northwell, Manhasset, NY
| | - Alexander M. Spring
- Division of Cardiovascular and Thoracic Surgery, Zucker School of Medicine at Hofstra/Northwell, Manhasset, NY
| | - Hugh Cassiere
- Division of Cardiovascular and Thoracic Surgery, Zucker School of Medicine at Hofstra/Northwell, Manhasset, NY
| | - Tylis Y. Chang
- Department of Pathology, Zucker School of Medicine at Hofstra/Northwell, Manhasset, NY
| | - Alan Hartman
- Division of Cardiovascular and Thoracic Surgery, Zucker School of Medicine at Hofstra/Northwell, Manhasset, NY
| | - Pey-Jen Yu
- Division of Cardiovascular and Thoracic Surgery, Zucker School of Medicine at Hofstra/Northwell, Manhasset, NY
- Address for reprints: Pey-Jen Yu, MD, 300 Community Dr, Manhasset, NY 11030.
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11
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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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Kataria V, Moore L, Harrison S, Hernandez O, Vaughan N, Schwartz G. Evaluation of Serotonin Release Assay and Enzyme-Linked Immunosorbent Assay Optical Density Thresholds for Heparin-Induced Thrombocytopenia in Patients on Extracorporeal Membrane Oxygenation. Crit Care Med 2020; 48:e82-e86. [PMID: 31939806 DOI: 10.1097/ccm.0000000000004090] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES Heparin-induced thrombocytopenia is a recognized concern in patients on extracorporeal life support. The purpose of this study was to evaluate the applicability of an enzyme-linked immunosorbent assay optical density threshold less than 1 to rule out heparin-induced thrombocytopenia in patients on extracorporeal membrane oxygenation. DESIGN Retrospective, single-center study. SETTING Patients were recruited from a prospectively maintained database of all patients on extracorporeal membrane oxygenation from 2012 to 2018 at a tertiary referral center. PATIENTS Forty-seven patients on extracorporeal membrane oxygenation support. INTERVENTIONS The primary objective was to evaluate the application of enzyme-linked immunosorbent assay optical density thresholds and the serotonin release assay in patients on extracorporeal membrane oxygenation. Patients were divided into two cohorts, serotonin release assay negative and serotonin release assay positive. In order to perform a sensitivity and specificity analysis of enzyme-linked immunosorbent assay optical density thresholds, heparin-induced thrombocytopenia negative was defined as an optical density less than 1.0 and heparin-induced thrombocytopenia positive as an optical density greater than or equal to 1.0. MEASUREMENTS AND MAIN RESULTS Utilizing the prespecified optical density thresholds, a specificity and negative predictive value of 89% and 95% were achieved, respectively. CONCLUSIONS This assessment has helped to identify optical density thresholds for patients undergoing extracorporeal membrane oxygenation. Our data suggest that an optical density threshold of 1.0 may aid clinicians in objectively ruling out heparin-induced thrombocytopenia without sending a confirmatory serotonin release assay. Increasing the optical density threshold to 1.0 resulted in a high specificity and negative predictive value.
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Affiliation(s)
- Vivek Kataria
- Department of Pharmacy, Baylor University Medical Center, Dallas, TX
| | - Leanne Moore
- Department of Pharmacy, Baylor University Medical Center, Dallas, TX
| | - Sarah Harrison
- Department of Pharmacy, Baylor University Medical Center, Dallas, TX
| | - Omar Hernandez
- Department of Perfusion Services, Baylor University Medical Center, Dallas, TX
| | - Nathan Vaughan
- Department of Surgery, Baylor University Medical Center, Dallas, TX
| | - Gary Schwartz
- Department of Thoracic Surgery and Lung Transplantation, Baylor University Medical Center, Dallas, TX
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Huynh A, Arnold DM, Kelton JG, Smith JW, Horsewood P, Clare R, Guarné A, Nazy I. Characterization of platelet factor 4 amino acids that bind pathogenic antibodies in heparin-induced thrombocytopenia. J Thromb Haemost 2019; 17:389-399. [PMID: 30582672 DOI: 10.1111/jth.14369] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Indexed: 12/18/2022]
Abstract
Essentials Many patients produce antibodies but few lead to heparin-induced thrombocytopenia (HIT). Pathogenic epitopes are difficult to identify as HIT antibodies are polyclonal and polyspecific. KKO binding to platelet factor 4 (PF4) depends on 13 amino acids, three of which are newly observed. Five amino acids in PF4 can help distinguish pathogenic from non-pathogenic antibodies. SUMMARY: Background Heparin-induced thrombocytopenia (HIT) is an adverse drug reaction that results in thrombocytopenia and, in some patients, thrombotic complications. HIT is mediated by antibodies that bind to complexes of platelet factor 4 (PF4) and heparin. The antigenic epitopes of these anti-PF4/heparin antibodies have not yet been precisely defined, because of the polyspecific immune response that characterizes HIT. Objectives To identify PF4 amino acids essential for binding pathogenic HIT antibodies. Methods Alanine scanning mutagenesis was utilized to produce 70 single point mutations of PF4. Each PF4 mutant was used in an enzyme immunoassay (EIA) to test their capacity to bind a platelet-activating murine monoclonal anti-PF4/heparin antibody (KKO) and HIT patient sera (n = 9). Results and Conclusions We identified 13 amino acids that were essential for binding KKO because they directly affected either the binding site or the antigenic conformation of PF4. We also identified 10 amino acids that were required for the binding of HIT patient sera and five of these amino acids were required for binding both KKO and the HIT patient sera. The 10 amino acids required for binding HIT sera were further tested to differentiate pathogenic HIT antibodies (platelet activating, n = 45) and non-pathogenic antibodies (EIA-positive but not platelet activating, n = 28). We identified five mutations of PF4 that were recognized to be essential for binding pathogenic HIT antibodies. Using alanine scanning mutagenesis, we characterized possible binding sites of pathogenic HIT antibodies on PF4.
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Affiliation(s)
- Angela Huynh
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Donald M Arnold
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
- McMaster Centre for Transfusion Research, Hamilton, Ontario, Canada
- Canadian Blood Services, Hamilton, Ontario, Canada
| | - John G Kelton
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - James W Smith
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Peter Horsewood
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Rumi Clare
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Alba Guarné
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
| | - Ishac Nazy
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
- McMaster Centre for Transfusion Research, Hamilton, Ontario, Canada
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Ivetic N, Arnold DM, Smith JW, Huynh A, Kelton JG, Nazy I. A platelet viability assay (PVA) for the diagnosis of heparin-induced thrombocytopenia. Platelets 2019; 30:1017-1021. [DOI: 10.1080/09537104.2018.1562169] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Nikola Ivetic
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
| | - Donald M. Arnold
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - James W. Smith
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Angela Huynh
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - John G. Kelton
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Ishac Nazy
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
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Patel R, Varga C. Heparin-induced thrombocytopenia in a cardiac surgery patient with early and persistent thrombocytopenia and initial negative immunological and functional assays. Thromb Res 2018; 169:93-95. [DOI: 10.1016/j.thromres.2018.07.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 06/28/2018] [Accepted: 07/03/2018] [Indexed: 10/28/2022]
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Maeda T, Nakagawa K, Murata K, Kanaumi Y, Seguchi S, Kawamura S, Kodama M, Kawai T, Kakutani I, Ohnishi Y, Kokame K, Okazaki H, Miyata S. Identifying patients at high risk of heparin-induced thrombocytopenia-associated thrombosis with a platelet activation assay using flow cytometry. Thromb Haemost 2017; 117:127-138. [DOI: 10.1160/th16-06-0482] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Accepted: 09/17/2016] [Indexed: 01/21/2023]
Abstract
SummaryTo diagnose heparin-induced thrombocytopenia (HIT), detection of platelet-activating antibodies (HIT antibodies) is crucial. However, serum platelet activation profiles vary across patients and depend on test conditions. We evaluated the association between clinical outcomes and platelet-activating profiles assessed by a platelet microparticle assay (PMA), which detects activation of washed platelets induced by HIT antibodies, in 401 consecutive patients clinically suspected of having HIT. We made modifications to the assay, such as donor selection for washed platelets that increased sensitivity. Serum that activated platelets at a therapeutic (but not high) heparin concentration was defined as positive. Of these, serum that activated platelets within 30 minutes or in the absence of heparin was defined as strongly positive. The remaining samples were considered weakly positive. As a result, 97 % and 93 % of patients who tested strongly and weakly positive had clinical profiles consistent with HIT, respectively. The incidence of thromboembolic events (TEEs) after heparin exposure in patients who tested strongly positive, weakly positive, and negative was 61 %, 40 %, and 29 %, respectively. Among patients who did not experience a TEE on the day HIT was suspected, there was no significant difference in the cumulative incidence of subsequent TEEs between patients who tested strongly and weakly positive when argatroban was initiated on the same day (19.0 % vs 7.1 %, p=0.313), but there was a significant difference when argatroban therapy was delayed by one or more days (61.1 % vs 17.6 %, p=0.007). The modified PMA is effective in diagnosing HIT and identifying patients at high risk for HIT-associated TEEs.Supplementary Material to this article is available online at www.thrombosis-online.com.
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17
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Vanderbilt CM, McFarland C, Lind SE. Evaluation of a Reflex Testing Algorithm for Suspected Heparin-Induced Thrombocytopenia. Am J Clin Pathol 2017; 148:390-397. [PMID: 29059268 DOI: 10.1093/ajcp/aqx078] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
OBJECTIVES We implemented a policy of reflex serotonin-release assay (SRA) testing for all patients with a positive heparin-induced thrombocytopenia (HIT) immunoassay. METHODS We identified all patients who had SRA testing sent as a consequence of a positive HIT immunoassay test. We reviewed charts of patients to calculate the 4Ts clinical score, determined the effect of testing on clinical management, and documented the change in utilization of direct thrombin inhibitors (DTIs). RESULTS The likelihood of a positive SRA varied with the optical density (OD) of the immunoassay. The performance of the immunoglobulin G (IgG)-specific and polytypic enzyme-linked immunosorbent assay was not statistically different. Both OD and 4Ts score correlated with the likelihood of a positive SRA but demonstrated poor specificity. Discontinuation of DTIs in patients with negative SRAs resulted in decreased drug utilization. CONCLUSIONS The IgG-specific HIT immunoassay OD correlates with the likelihood of a positive SRA but does not achieve high specificity. The reflex testing algorithm allows for definitive classification of patients, and the cost of such a reflex testing program may be offset by decreased utilization of DTIs.
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Affiliation(s)
| | - Craig McFarland
- Medicine, University of Colorado School of Medicine and the University of Colorado Hospital, Aurora
| | - Stuart E Lind
- Departments of Pathology
- Medicine, University of Colorado School of Medicine and the University of Colorado Hospital, Aurora
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Abstract
PURPOSE OF REVIEW The purpose of this review is to summarize recent findings on heparin-induced thrombocytopenia (HIT), a prothrombotic disorder caused by platelet-activating IgG targeting platelet factor 4 (PF4)/polyanion complexes. RECENT FINDINGS HIT can explain unusual clinical events, including adrenal hemorrhages, arterial/intracardiac thrombosis, skin necrosis, anaphylactoid reactions, and disseminated intravascular coagulation. Sometimes, HIT begins/worsens after stopping heparin ('delayed-onset' HIT). Various HIT-mimicking disorders are recognized (e.g., acute disseminated intravascular coagulation/'shock liver' with limb ischemia). HIT has features of both B-cell and T-cell immune responses; uptake of PF4/heparin complexes into macrophages ('macropinocytosis') facilitates the anti-PF4/heparin immune response. Antibody-induced activation of monocytes and platelets via their FcγIIA receptors triggers an intense procoagulant response. Sometimes, HIT antibodies recognize PF4 bound to (platelet-associated) chondroitin sulfate, explaining how HIT might occur without concurrent or recent heparin (delayed-onset HIT, 'spontaneous HIT syndrome'). The molecular structure of HIT antigen(s) has been characterized, providing a rationale for future drug design to avoid HIT and improve its treatment. The poor correlation between partial thromboplastin time and plasma argatroban levels (risking subtherapeutic anticoagulation) and need for intravenous administration of argatroban have led to increasing 'off-label' treatment with fondaparinux or one of the direct oral anticoagulants. SUMMARY Understanding the molecular mechanisms and unusual clinical features of HIT will improve its management.
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19
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Markovic I, Debeljak Z, Bosnjak B, Marijanovic M. False positive immunoassay for heparin-induced thrombocytopenia in the presence of monoclonal gammopathy: a case report. Biochem Med (Zagreb) 2017; 27:030801. [PMID: 29180919 PMCID: PMC5696753 DOI: 10.11613/bm.2017.030801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 09/19/2017] [Indexed: 11/09/2022] Open
Abstract
Heparin induced thrombocytopenia (HIT) is a life-threatening disorder which diagnosis depends on laboratory evaluation. The objective of this report is to present the impact of different laboratory methods for HIT detection on the diagnostic evaluation process. In this case, a 78-year old female patient previously diagnosed with monoclonal gammopathy of undetermined significance (MGUS) was administered with heparin for pulmonary embolism treatment. Patient’s initial diagnostic work-up (determination of platelet count and prothrombin time measurement for monitoring of pharmacotherapy) was followed by the clinical estimation of HIT likelihood by “4Ts” score, two immunoassays (ID-PaGIA Heparin/PF4 Antibody Test and ELISA PF4 IgG assay) and one functional test called high-performance liquid chromatography serotonin release assay (HPLC-SRA). The result of “4Ts” score indicated a low likelihood of HIT but persistent thrombocytopenia that appeared days after discontinuation of heparin therapy suggested delayed-onset HIT. Both immunoassays were positive for presence of HIT-autoantibodies, while the functional HPLC-SRA was negative. Since different methods gave opposing results, their interpretation required great attention. In comparison to the HPLC-SRA, immunoassays are prone to the analytical interferences associated with the presence of non-specific antibodies, which may lead to false positive results. In this case, where the patient is known to produce antibodies of undetermined significance, HIT was ruled out as the possible cause of persistent thrombocytopenia primarily due to the negative result of HPLC-SRA, which is not prone to this type of interferences, but also due to the low “4Ts” clinical score.
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Affiliation(s)
- Ivana Markovic
- Institute of Clinical Laboratory Diagnostics, Osijek University Hospital, Osijek, Croatia.,Faculty of Medicine, JJ Strossmayer University of Osijek, Osijek, Croatia
| | - Zeljko Debeljak
- Institute of Clinical Laboratory Diagnostics, Osijek University Hospital, Osijek, Croatia.,Faculty of Medicine, JJ Strossmayer University of Osijek, Osijek, Croatia
| | - Bojana Bosnjak
- Faculty of Medicine, JJ Strossmayer University of Osijek, Osijek, Croatia.,Institute of Transfusion Medicine, Osijek University Hospital, Osijek, Croatia
| | - Maja Marijanovic
- Institute of Transfusion Medicine, Osijek University Hospital, Osijek, Croatia
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20
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Choxi AA, Patel PA, Augoustides JG, Benitez-Lopez J, Gutsche JT, Murad H, Rodriguez-Blanco YF, Fabbro M, Crookston KP, Gerstein NS. Bivalirudin for Cardiopulmonary Bypass in the Setting of Heparin-Induced Thrombocytopenia and Combined Heart and Kidney Transplantation—Diagnostic and Therapeutic Challenges. J Cardiothorac Vasc Anesth 2017; 31:354-364. [DOI: 10.1053/j.jvca.2016.07.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2016] [Indexed: 12/25/2022]
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21
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Brent J, Burkhart K, Dargan P, Hatten B, Megarbane B, Palmer R, White J. Adverse Drug Reactions in the Intensive Care Unit. CRITICAL CARE TOXICOLOGY 2017. [PMCID: PMC7153447 DOI: 10.1007/978-3-319-17900-1_33] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Adverse drug reactions (ADRs) are undesirable effects of medications used in normal doses [1]. ADRs can occur during treatment in an intensive care unit (ICU) or result in ICU admissions. A meta-analysis of 4139 studies suggests the incidence of ADRs among hospitalized patients is 17% [2]. Because of underreporting and misdiagnosis, the incidence of ADRs may be much higher and has been reported to be as high as 36% [3]. Critically ill patients are at especially high risk because of medical complexity, numerous high-alert medications, complex and often challenging drug dosing and medication regimens, and opportunity for error related to the distractions of the ICU environment [4]. Table 1 summarizes the ADRs included in this chapter.
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Affiliation(s)
- Jeffrey Brent
- Department of Medicine, Division of Clinical Pharmacology and Toxicology, University of Colorado, School of Medicine, Aurora, Colorado USA
| | - Keith Burkhart
- FDA, Office of New Drugs/Immediate Office, Center for Drug Evaluation and Research, Silver Spring, Maryland USA
| | - Paul Dargan
- Clinical Toxicology, St Thomas’ Hospital, Silver Spring, Maryland USA
| | - Benjamin Hatten
- Toxicology Associates, University of Colorado, School of Medicine, Denver, Colorado USA
| | - Bruno Megarbane
- Medical Toxicological Intensive Care Unit, Lariboisiere Hospital, Paris-Diderot University, Paris, France
| | - Robert Palmer
- Toxicology Associates, University of Colorado, School of Medicine, Denver, Colorado USA
| | - Julian White
- Toxinology Department, Women’s and Children’s Hospital, North Adelaide, South Australia Australia
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22
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Sun L, Gimotty PA, Lakshmanan S, Cuker A. Diagnostic accuracy of rapid immunoassays for heparin-induced thrombocytopenia. A systematic review and meta-analysis. Thromb Haemost 2016; 115:1044-55. [PMID: 26763074 DOI: 10.1160/th15-06-0523] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 12/03/2015] [Indexed: 01/15/2023]
Abstract
The platelet factor 4/heparin ELISA has limited specificity for heparin-induced thrombocytopenia (HIT) and frequently does not provide same-day results. Rapid immunoassays (RIs) have been developed which provide results in 30 minutes or less. We conducted a systematic review and meta-analysis to evaluate the diagnostic accuracy of RIs for HIT. We searched the literature for studies in which samples from patients with suspected HIT were tested using a RI and a functional assay against which the performance of the RI could be measured. We performed sensitivity analyses of studies that directly compared different RIs with each other and with ELISAs. Estimates of sensitivity and specificity for each RI were calculated. Twenty-three articles, collectively involving six different RIs, met eligibility criteria. All RIs exhibited high sensitivity (0.96 to 1.00); there was wider variability in specificity (0.68 to 0.94). Specificity of the IgG-specific chemiluminescent assay (IgG-CA) was greater than the polyspecific chemiluminescent assay [0.94 (95 %CI 0.89-0.99) vs 0.82 (0.77-0.87)]. The particle gel immunoassay demonstrated greater specificity than the polyspecific ELISA [0.96 (0.95-0.97) vs 0.91 (0.89-0.92)]. The IgG-CA and lateral flow immunoassay [0.94 (0.91-0.97)] exhibited greater specificity than the IgG-specific ELISA [0.86 (0.82-0.90)]. Given their high sensitivity and rapid turnaround time, RIs are a reliable means of excluding HIT at the point-of-care in patients with low or intermediate clinical probability. Additionally, some RIs have greater specificity than HIT ELISAs. In summary, IgG-specific RIs appear to have improved diagnostic accuracy compared with ELISAs in patients with suspected HIT and may reduce misdiagnosis and overtreatment.
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Affiliation(s)
| | | | | | - Adam Cuker
- Adam Cuker, MD, MS, Hospital of the University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104, USA, Tel.: +1 215 615 6555, Fax: +1 215 615 6599, E-mail:
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23
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Nazi I, Arnold DM, Warkentin TE, Smith JW, Staibano P, Kelton JG. Distinguishing between anti-platelet factor 4/heparin antibodies that can and cannot cause heparin-induced thrombocytopenia. J Thromb Haemost 2015; 13:1900-7. [PMID: 26291604 DOI: 10.1111/jth.13066] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Accepted: 07/20/2015] [Indexed: 01/23/2023]
Abstract
BACKGROUND Many patients exposed to heparin develop antibodies against platelet factor 4 (PF4) and heparin, yet only those antibodies that activate platelets cause heparin-induced thrombocytopenia (HIT). Patients who produce anti-PF4/heparin antibodies without developing HIT either have antibodies that do not cause platelet activation or produce pathogenic antibodies at levels that are insufficient to cause HIT. Understanding the differences between anti-PF4/heparin antibodies with and without HIT will improve test methods and reduce overdiagnosis. AIMS To investigate the presence of low levels of platelet-activating antibodies in patients investigated for HIT who had anti-PF4/heparin antibodies but failed to cause platelet activation in the (14) C-serotonin release assay (SRA). MATERIALS/METHODS We developed a platelet activation assay similar to the SRA using exogenous PF4 without added heparin (PF4-SRA). This assay was able to detect low levels of platelet-activating antibodies. We used this PF4-SRA to test for platelet-activating antibodies in patients investigated for HIT. RESULTS The PF4-SRA detected platelet-activating antibodies in seven (100%) of seven SRA-positive sera even after the samples were diluted until they were no longer positive in the standard SRA. Platelet-activating antibodies were detected in 14 (36%) of 39 patients who had anti-PF4/heparin antibodies but tested negative in the SRA and did not have clinical HIT. The clinical diagnosis of HIT was confirmed by chart review and concordant with the SRA results. CONCLUSIONS A subset of heparin-treated patients produce subthreshold levels of platelet-activating anti-PF4/heparin antibodies that do not cause HIT. An increase in the titer of these pathogenic antibodies, along with permissive clinical conditions, could lead to HIT.
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Affiliation(s)
- I Nazi
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON, Canada
| | - D M Arnold
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON, Canada
- Canadian Blood Services, Hamilton, ON, Canada
| | - T E Warkentin
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON, Canada
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada
| | - J W Smith
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON, Canada
| | - P Staibano
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON, Canada
| | - J G Kelton
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON, Canada
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Sanidas EA, Viniou NA, Diamantopoulos P, Barbetseas J. Heparin induced thrombocytopenia. Contemporary therapeutic approaches in light of the new oral anticoagulants. Hamostaseologie 2015; 35:372-5. [PMID: 26302031 DOI: 10.5482/hamo-15-04-0013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Accepted: 08/12/2015] [Indexed: 12/12/2022] Open
Abstract
Heparin induced thrombocytopenia (HIT) is a prothrombotic syndrome initiated by platelet-activating auto-antibodies with potentially devastating complications. Once the diagnosis of HIT is suspected, discontinuation of heparin and treatment with an alternative anticoagulant are mandatory. While established drugs for HIT are no longer available, parenteral factor Xa inhibitors, thrombin inhibitors and perhaps the direct oral anticoagulants provide additional treatment options. The aim of this review was to highlight the current clinical aspects regarding HIT focusing on the role of novel medications.
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Affiliation(s)
- E A Sanidas
- Elias Sanidas MD, PhD, FACC, FESC, Department of Cardiology, Laiko General Hospital, 17 Agiou Thoma street, 11527, Athens, Greece,
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25
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Bianchi CF, Petrucci O. Another off-label novel oral anticoagulant to HIT cardiac surgery patients. J Thorac Cardiovasc Surg 2015; 150:e20-2. [DOI: 10.1016/j.jtcvs.2015.05.024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Accepted: 05/06/2015] [Indexed: 11/16/2022]
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