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Hamostaseologie 2023; 43(01): 022-027
DOI: 10.1055/a-1986-1556
Original Article

Diagnostic Performance of a Particle Gel Immunoassay in Vaccine-Induced Immune Thrombotic Thrombocytopenia

Günalp Uzun
1   Centre for Clinical Transfusion Medicine, University Hospital of Tuebingen, Tuebingen, Germany
,
Karina Althaus
1   Centre for Clinical Transfusion Medicine, University Hospital of Tuebingen, Tuebingen, Germany
2   Institute for Clinical and Experimental Transfusion Medicine, Medical Faculty of Tuebingen, University Hospital of Tuebingen, Tuebingen, Germany
,
Stefanie Hammer
1   Centre for Clinical Transfusion Medicine, University Hospital of Tuebingen, Tuebingen, Germany
,
Yvonne Wanner
1   Centre for Clinical Transfusion Medicine, University Hospital of Tuebingen, Tuebingen, Germany
,
Stefanie Nowak-Harnau
1   Centre for Clinical Transfusion Medicine, University Hospital of Tuebingen, Tuebingen, Germany
,
Sigrid Enkel
1   Centre for Clinical Transfusion Medicine, University Hospital of Tuebingen, Tuebingen, Germany
,
Tamam Bakchoul
1   Centre for Clinical Transfusion Medicine, University Hospital of Tuebingen, Tuebingen, Germany
2   Institute for Clinical and Experimental Transfusion Medicine, Medical Faculty of Tuebingen, University Hospital of Tuebingen, Tuebingen, Germany
› Author Affiliations Funding/Acknowledgments This work was supported by grants from the German Research Foundation and from the Herzstiftung to T.B. (BA5158/4 and TSG-Study), by special funds from the state of Baden-Württemberg for coagulation research and blood donation service of German Red Cross to T.B. This study was partially presented as a poster contribution at the 17th Annual Meeting of the German Society for Clinical Chemistry and Laboratory [17. Jahrestagung der Deutschen Gesellschaft für Klinische Chemie und Laboratoriumsmedizin], October 13–14, 2022, in Mannheim, Germany. We thank Barbara Gubitz for her help during patient chart review.
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Abstract

Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a rare but serious complication of adenoviral vector-based COVID-19 vaccines. Similar to heparin-induced thrombocytopenia (HIT), antibodies reacting to platelet factor 4 (PF4) are responsible for platelet activation in VITT. The diagnosis of VITT includes the detection of anti-PF4 antibodies. Particle gel immunoassay (PaGIA) is one of the rapid immunoassays that is commonly used in the diagnosis of HIT to detect anti-PF4 antibodies. The aim of this study was to investigate the diagnostic performance of PaGIA in patients suspected of VITT. In this retrospective, single-center study, the correlation between PaGIA, enzyme immunoassay (EIA), and modified heparin-induced platelet aggregation assay (HIPA) in patients with findings suggestive of VITT was investigated. A commercially available PF4 rapid immunoassay (ID PaGIA H/PF4, Bio-Rad-DiaMed GmbH, Switzerland) and an anti-PF4/heparin EIA (ZYMUTEST HIA IgG, Hyphen Biomed) were used according to manufacturer's instructions. Modified HIPA was accepted as the gold standard test. Between March 8 and November 19, 2021, a total of 34 samples from clinically well-characterized patients (14 males, 20 females, mean age: 48.2 ± 18.2 years) were analyzed with PaGIA, EIA, and modified HIPA. VITT was diagnosed in 15 patients. Sensitivity and specificity of PaGIA were 54 and 67%, respectively. Anti-PF4/heparin optical density values were not significantly different between PaGIA positive and negative samples (p = 0.586). The sensitivity and specificity of EIA, on the other hand, were 87 and 100%, respectively. In conclusion, PaGIA is not reliable in the diagnosis of VITT because of its low sensitivity and specificity.

Keywords

diagnostic test - platelet factor 4 - rapid immunoassay - platelet immunology

Authors' Contributions

G.U., K.A., and T.B. designed the study. G.U., K.A., S.H., Y.W., S.N-H., and S.E. collected the clinical data and analyzed the test results. G.U., K.A., and T.B. performed the statistical analyses, interpreted the results, and wrote the manuscript. All authors read and approved the manuscript.




Publication History

Received: 14 October 2022

Accepted: 22 November 2022

Article published online:
20 February 2023

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