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Machhi R, Lindholm PF, Cooke D, Groth M, Martin KA. Improving Judicious Use of Heparin-Induced Thrombocytopenia Testing Through Electronic Health Record-Based Intervention. Jt Comm J Qual Patient Saf 2023; 49:648-654. [PMID: 37479590 PMCID: PMC10615670 DOI: 10.1016/j.jcjq.2023.06.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 06/26/2023] [Accepted: 06/28/2023] [Indexed: 07/23/2023]
Abstract
BACKGROUND Heparin-induced thrombocytopenia (HIT) is an immune-mediated drug reaction that can cause thromboembolism in the setting of thrombocytopenia. An enzyme-linked immunosorbent assay (ELISA)-based assay to screen for HIT antibodies (HAb) is available but has relatively low specificity and a correspondingly high false positive rate. The 4Ts score has been validated to determine the pretest probability of HIT. The authors hypothesized that an electronic health record (EHR)-based clinical decision support (CDS) tool incorporating the 4Ts score would reduce the volume of HAb orders. METHODS After implementing a CDS tool into the EHR, the researchers retrospectively evaluated the impact from November 2019 to October 2021, compared to a preintervention period (January to October 2019). The primary outcome was average tests per month. Secondary outcomes included rates of tests ordered per total inpatient encounters and proportion of HAb sent despite low 4Ts score in the postintervention study period. RESULTS Of 1,833 HAb sent during the study period, 1,217 occurred in the postintervention period. In the postintervention period compared with the preintervention period, the average orders per month was 50.5 (standard deviation [SD] 9.7) vs. 61.6 (SD 7.2) (p = 0.003), and the order incidence rate was 8.0 per 1,000 patient encounters postintervention vs. 9.2 per 1,000 patient encounters preintervention (rate ratio [RR] 0.87, 95% confidence interval [CI] 0.79-0.96, p = 0.002). Postintervention, 252 (20.7%) had a 4Ts score calculated as low probability, 759 (62.4%) as intermediate probability, and 131 (10.8%) as high probability, and 75 had no associated 4Ts score. CONCLUSION Implementation of a simple CDS tool reduced the rate of HAb orders, reducing unnecessary HAb testing.
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Li S, Fan L, Wang S, Zhao Y. Prospective evaluation of heparin-induced thrombocytopenia expert probability and 4T scores in Chinese patients with suspected heparin-induced thrombocytopenia. Chin Med J (Engl) 2019; 132:1441-1447. [PMID: 31205102 PMCID: PMC6629329 DOI: 10.1097/cm9.0000000000000261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Supplemental Digital Content is available in the text Background Diagnosis of heparin-induced thrombocytopenia (HIT) is challenging. This study aimed to compare the diagnostic performance of HIT expert probability (HEP) and 4T scores, and to evaluate the inter-observer reliability for the 4T score in a clinical setting. Methods This prospective study included HIT-suspected patients between 2016 and 2018. Three hematologists assessed the HEP and 4T scores. Correlations between scores and anti-platelet factor 4 (anti-PF4)/heparin antibodies were evaluated. Receiver operating characteristic curves and area under the curve (AUC) were used to assess the predictive accuracy of these two scoring models. The intraclass correlation coefficient (ICC) was used to assess the inter-observer agreement of 4T scores between residents and hematologists. Results Of the 89 subjects included, 22 (24.7%) were positive for anti-PF4/heparin antibody. The correlations between antibody titer and either HEP or 4T scores were similar (r = 0.392, P < 0.01 for the HEP score; r = 0.444, P < 0.01 for the 4T score). No significant difference in the diagnostic performance was displayed between these two scores (AUC for the HEP score: 0.778 vs. AUC for the 4T score: 0.741, P = 0.357). Only 72 4T scores were collected from the residents, with a surprisingly low percentage of observers (43.1%) presenting the four individual item scores which made up their 4T score. The AUC of 4T score assessed by residents and hematologists was 0.657 (95% confidence interval [CI]: 536–0.765) and 0.780 (95% CI: 0.667–0.869, P < 0.05), respectively. The ICC of 4T score between residents and hematologists was 0.49 (95% CI: 0.29–0.65, P < 0.01), demonstrating a fair inter-observer agreement. Conclusions The HEP score does not display a better performance for predicting HIT than the 4T score. With the unsatisfactory completion rate, the inter-observer agreement of 4T score in a tertiary hospital is fair, underscoring the necessity for continuing education for physicians.
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Bashover EM, Stefaniuk CM, Harding CV, Maitta RW. Use of a whole-cell ELISA to detect additional antibodies in setting of suspected heparin-induced thrombocytopenia. Eur J Haematol 2019; 103:99-106. [PMID: 31107976 DOI: 10.1111/ejh.13263] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 05/17/2019] [Indexed: 01/13/2023]
Abstract
OBJECTIVES Type II heparin-induced thrombocytopenia (HIT) is mediated by formation of antibodies to platelet factor 4 (PF4)-heparin complexes. We evaluated anti-PF4-heparin-negative samples for the presence of additional anti-platelet and anti-red blood cell (RBC) antibodies using whole-cell platelet/ RBC ELISAs we developed. METHODS Seventy-three samples tested for anti-PF4-heparin by ELISA were included: 62 tested negative, 9 tested positive, and 2 had equivocal results. Plasma specimens from healthy donors were used as controls. RESULTS 100% (9/9) anti-PF4-positive samples had anti-platelet antibodies detected by whole-cell platelet ELISA. 42.2% (27/64) anti-PF4-heparin-negative samples were negative for anti-platelet and anti-RBC antibodies. 32.8% (21/64) negative samples showed reactivity to both platelets and RBC; 12.5% (8/64) negative samples were each reactive with either platelet or RBC ELISA, respectively. Additionally, two samples that tested equivocal by anti-PF4-heparin ELISA had antibodies to both platelets and RBC by whole-cell ELISA. CONCLUSIONS Our study suggests that patients with thrombocytopenia testing negative for anti-PF4-heparin may still harbor antibodies to platelets. However, additional research is needed to determine the significance of these antibodies. Nevertheless, these findings may encourage clinicians to further investigate patients with possible immune-mediated etiologies of thrombocytopenia and anemia.
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Affiliation(s)
- Eva M Bashover
- Department of Pathology, Case Western Reserve University School of Medicine, University Hospitals Cleveland Medical Center, Cleveland, Ohio
| | - Catherine M Stefaniuk
- Department of Pathology, Case Western Reserve University School of Medicine, University Hospitals Cleveland Medical Center, Cleveland, Ohio
| | - Clifford V Harding
- Department of Pathology, Case Western Reserve University School of Medicine, University Hospitals Cleveland Medical Center, Cleveland, Ohio
| | - Robert W Maitta
- Department of Pathology, Case Western Reserve University School of Medicine, University Hospitals Cleveland Medical Center, Cleveland, Ohio
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Chen W, Ha JP, Hong H, Maitta RW. Absolute immature platelet counts in the setting of suspected heparin-induced thrombocytopenia may predict anti-PF4-heparin immunoassay testing results. Transfus Apher Sci 2018; 57:507-511. [DOI: 10.1016/j.transci.2018.04.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Revised: 03/30/2018] [Accepted: 04/01/2018] [Indexed: 12/15/2022]
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Williams JS, Autori PJ, Kidd SK, Piazza G, Connors MC, Czeisler CA, Scheuermaier KD, Duffy J, Klerman EB, Scheer FA, Kozak M, Driscoll SM, Goldhaber SZ. Heparin-Induced Thrombocytopenia in Healthy Individuals with Continuous Heparin Infusion. TH Open 2018; 2:e49-e53. [PMID: 31249929 PMCID: PMC6524859 DOI: 10.1055/s-0038-1624565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 12/05/2017] [Indexed: 10/26/2022] Open
Abstract
The risk for developing heparin-induced thrombocytopenia in healthy individuals is thought to be low, but monitoring recommendations remain controversial. Therefore, a retrospective cohort study was conducted to identify the incidence of thrombocytopenic events in a healthy research population exposed and re-exposed to continuous intravenous (IV) unfractionated heparin. The Division of Sleep Medicine and the Centre for Clinical Investigations at Brigham and Women's Hospital, Boston, Massachusetts, United States, instituted a standardized platelet monitoring procedure for all research protocols that involved heparin to detect platelet count decreases. Protocol-related frequent blood sampling required use of continuous IV unfractionated heparin infusion (5,000 unit/L in 0.45% saline at 40 mL/h) to maintain line patency over extended periods of IV access. From the years 2009 to 2012, a total of 273 healthy volunteers enrolled in Sleep Medicine research protocols met study criteria as having been exposed and/or re-exposed to continuously infused intravenous heparin for at least 4 hours. The mean continuous heparin exposure time was 88 ± 82 SD hours with a total of 397 heparin exposure and re-exposure events. Platelet count measurements were obtained on 629 occasions, representing a range from 2 to 9 draws per participant. No platelet count decrease of more than 50% was detected. There were no detected adverse bleeding or thrombotic events. In this retrospective study of healthy volunteers involved in a rigorously applied inpatient platelet monitoring protocol, heparin exposure and re-exposure did not lower platelet concentration and, therefore, does not appear to be associated with increased risk of HIT in this population.
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Affiliation(s)
- Jonathan S Williams
- Division of Endocrinology, Diabetes, and Hypertension, Brigham and Women's Hospital, Boston, Massachusetts, United States
| | - Paula J Autori
- Center for Clinical Investigations, Brigham and Women's Hospital, Boston, Massachusetts, United States
| | - Stephen K Kidd
- Department of Cardiology, Northwestern Memorial Hospital, Chicago, Illinois, United States
| | - Gregory Piazza
- Cardiovascular Division, Brigham and Women's Hospital, Boston, Massachusetts, United States
| | - Molly C Connors
- Division of Endocrinology, Diabetes, and Hypertension, Brigham and Women's Hospital, Boston, Massachusetts, United States
| | - Charles A Czeisler
- Division of Sleep Medicine, Brigham and Women's Hospital, Boston, Massachusetts, United States
| | - Karine D Scheuermaier
- Wits Sleep Laboratory, University of the Witwatersrand, Johannesburg, Braamfontein, South Africa
| | - Jeanne Duffy
- Division of Sleep Medicine, Brigham and Women's Hospital, Boston, Massachusetts, United States
| | - Elizabeth B Klerman
- Division of Sleep Medicine, Brigham and Women's Hospital, Boston, Massachusetts, United States
| | - Frank A Scheer
- Division of Sleep Medicine, Brigham and Women's Hospital, Boston, Massachusetts, United States
| | - Marjorie Kozak
- Center for Clinical Investigations, Brigham and Women's Hospital, Boston, Massachusetts, United States
| | - Sheila M Driscoll
- Center for Clinical Investigations, Brigham and Women's Hospital, Boston, Massachusetts, United States
| | - Samuel Z Goldhaber
- Cardiovascular Division, Brigham and Women's Hospital, Boston, Massachusetts, United States
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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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