Hamostaseologie 2025; 45(S 01): S36
DOI: 10.1055/s-0044-1801596
Abstracts
Topics
T-06 Diagnostics and laboratory tests

The dynamic range of immunoassays for heparin-induced thrombocytopenia

Authors

  • H Nilius

    1   Inselspital University Hospital Bern, Department of Clinical Chemistry, Bern, Switzerland
    2   University of Bern, Graduate School for Health Sciencesuat, Bern, Switzerland

  • S Naas

    1   Inselspital University Hospital Bern, Department of Clinical Chemistry, Bern, Switzerland

  • J-D Studt

    3   University and University Hospital Zurich, Division of Medical Oncology and Hematology, Zürich, Switzerland

  • D A Tsakiris

    4   Basel University Hospital, Department of Haematology, Basel, Switzerland

  • A Greinacher

    5   Universitätsmedizin Greifswald, Institut für Immunologie und Transfusionsmedizin, Greifswald, Germany

  • A Mendez

    6   Kantonsspital Aarau, Institute of Laboratory Medicine, Aarau, Switzerland

  • A Schmidt

    7   Municipal Hospital Zurich Triemli, Institute of Laboratory Medicine and Clinic of Medical Oncology and Hematology, Zürich, Switzerland

  • W A Wuillemin

    8   Cantonal Hospital of Lucerne and University of Bern, Division of Hematology and Central Hematology Laboratory, Lucerne, Switzerland

  • B Gerber

    9   Oncology Institute of Southern Switzerland, Clinic of Hematology, Bellinzona, Switzerland

  • P Vishnu

    10   University of Washington, Fred Hutchinson Cancer Center, Division of Hematology, Seattle, USA

  • L Graf

    11   Cantonal Hospital of St Gallen, St Gallen, Switzerland

  • J A Kremer Hovinga

    12   Inselspital Bern University Hospital, Department of Hematology and Central Hematology Laboratory, Bern, Switzerland

  • T Bakchoul

    13   University Hospital of Tübingen, Centre for Clinical Transfusion Medicine, Tübingen, Germany

  • C Nakas

    1   Inselspital University Hospital Bern, Department of Clinical Chemistry, Bern, Switzerland
    14   University of Thessaly, Laboratory of Biometry, School of Agriculture, Volos, Greece

  • M Nagler

    1   Inselspital University Hospital Bern, Department of Clinical Chemistry, Bern, Switzerland
    15   University of Bern, Bern, Switzerland
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Introduction: Following the current guidelines, immunoassays for the diagnosis of heparin-induced thrombocytopenia (HIT) are interpreted in a dichotomous manner, categorizing test results as either positive or negative. However, the extent to which test results hold diagnostic significance across the entire dynamic range remains unclear.

Method: We utilized data from the prospective TORADI-HIT study, comprising 1393 consecutive patients with suspected HIT, to assess the diagnostic significance of three H/PF4 -immunoassay test results across their respective dynamic ranges (HemoSil Acustar HIT IgG [CLIA], Lifecodes PF4 IgG [ELISA], Diamed ID H-PF4 [PaGIA]). The diagnosis of HIT was determined by a washed-platelet heparin-induced platelet activation assay (HIPA). For each measurement point in the dataset, we computed likelihood ratios (LR), sensitivities, and specificities.

Results: The prevalence of HIT was 8.5% (n=119). A likelihood ratio of≥10 was first achieved at 0.3% of the dynamic range (0.4 U/ml; CLIA), 16% (0.64 OD; ELISA), and 1.6% (1:4 titre; PaGIA), respectively. A likelihood ratio of≥100 was present at 9.4% (12 U/ml; CLIA), 75.0% (3.0 OD; ELISA), 25.0% (1:64 titre; PaGIA), respectively. The slope of the linear regression line (LR ~ dynamic range) was 9.5 (CLIA), 0.9 (ELISA), and 4.6 (PaGIA). To provide post-test probabilities for individual test results, we calculated interval-specific likelihood ratios and integrated it into a web-based calculator (https://pcd-research.shinyapps.io/BayesianCalculator/).

Conclusion: In conclusion, despite all immunoassays demonstrating an association between diagnostic significance and results, the strength of that association varies with the assay, with the CLIA having the largest increase per measurement unit.



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Artikel online veröffentlicht:
13. Februar 2025

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