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    Poster Networking

    Platelet Disorders, von Willebrand Disease and Thrombotic Microangiopathies

    Poster Networking Session

    PB0345 - Diagnosing heparin-induced thrombocytopenia: A prospective multicentre study

    Sunday, June 25, 2023
    18:30 – 19:30 ET
    Room: Exhibition

      Co-Author(s)

    • EL

      Emil List Larsen

      Resident
      Department of Clinical Biochemistry, Copenhagen University Hospital – Rigshospitalet
      Copenhagen, Hovedstaden, Denmark

      • Presenting Author(s)

    • Henning Nilius, MD, MSc (he/him/his)

      PhD Student & Resident
      Department of Clinical Chemistry, Inselspital, Bern University Hospital, and University of Bern, Bern, Switzerland
      Bern, Bern, Switzerland

      • Co-Author(s)

    • JS

      Jan-Dirk Studt

      Senior Physician
      Division of Medical Oncology and Hematology, University Hospital Zurich
      Zurich, Zurich, Switzerland

    • DT

      Dimitrios A. A. Tsakiris

      Professor
      Diagnostic Haematology, Basel University Hospital
      Basel, Basel-Stadt, Switzerland

    • Andreas Greinacher, MD

      Professor; Head of Institute
      Institut für Transfusionsmedizin, Universitätsmedizin Greifswald.
      Greifswald, Mecklenburg-Vorpommern, Germany

    • AM

      Adriana Mendez

      Senior Physician
      Department of Laboratory Medicine, Kantonsspital Aarau
      Aarau, Aargau, Switzerland

    • AS

      Adrian Schmidt

      Senior Physician
      Institute of Laboratory Medicine and Clinic of Medical Oncology and Hematology, City Hospital Triemli
      Zurich, Zurich, Switzerland

    • WW

      Walter A. A. Wuillemin

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

    • BG

      Bernhard Gerber

      Senior Physician
      Clinic of Hematology, Oncology Institute of Southern Switzerland
      Bellinzona, Ticino, Switzerland

    • PV

      Prakash Vishnu

      Consultant
      Departments of Hematology, St. Michael Medical Center, Virginia Mason Franciscan Health
      Seattle, Washington, United States

    • LG

      Lukas Graf

      Senior Physician
      Center for Laboratory Medicine, Hemophilia- and Hemostasis Center St. Gallen
      St. Gallen, Sankt Gallen, Switzerland

    • JK

      Johanna A. Kremer-Hovinga

      Professor
      Centre of Laboratory Medicine Section Hemostasis Inselspital Bern
      Bern, Bern, Switzerland

    • JG

      Jens P. Goetze

      Clinical Professor
      Department of Clinical Biochemistry, Copenhagen University Hospital – Rigshospitalet
      Copenhagen, Hovedstaden, Denmark

    • Tamam Bakchoul, MD (he/him/his)

      Medical Director
      Center for Clinical Transfusion Medicine, University Hospital of Tübingen
      Tübingen, Baden-Wurttemberg, Germany

    • Michael Nagler, MD, PhD, MSc

      Deputy Head
      Department of Clinical Chemistry, Inselspital, Bern University Hospital, and University of Bern, Bern, Switzerland
      Bern, Bern, Switzerland

    Background: Heparin-induced thrombocytopenia (HIT) is a life-threatening condition that requires urgent diagnostic clarification.

    Aims: Here we evaluated the current diagnostic practice for managing the suspicion of HIT in a prospective multicentre cohort study.

    Methods: Consecutive patients with suspected HIT were prospectively included in 11 study centers. Detailed clinical data and laboratory information were recorded and serum samples obtained. Platelet factor 4 (PF4)/heparin antibodies were quantified using an automated chemiluminescent immunoassay (CLIA; HemosIL AcuStar HIT-IgG). A washed-platelet heparin-induced platelet activation (HIPA) test was used as a reference standard to define HIT. The diagnostic accuracy of the 4Ts score, the CLIA, and the recommended algorithm serially combining both tests was examined.

    Results: Out of 1’448 patients included between 2018 and 2021, 1’318 were available for the current analysis. HIPA was positive in 111 patients (prevalence 8.4%). The median age was 67 years (inter-quartile range, IQR, 57 to 75), and the most frequent setting was intensive care unit (37.0%) or cardiovascular surgery (33.0%). The 4Ts score was scored as low risk in 625 patients (46.8%). The numbers of false-negative patients were 10 (0.8%; 4Ts score), 5 (0.4%; CLIA), and 15 (1.1%; current algorithm). The numbers of false-positive patients were 592 (44.9%; 4Ts score), 73 (5.5%; CLIA), and 50 (3.8%; algorithm), respectively.

    Conclusion(s): Applying the currently recommended diagnostic algorithm in clinical practice, only half of the patients require antibody testing. A significant number of patients, however, are misclassified by the algorithm, which can lead to delayed diagnosis (13.5%, false negative) and overtreatment (4.1%, false positive). Development of improved diagnostic algorithms for HIT diagnosis should be pursued.