Abstract Number: PB0570
Meeting: ISTH 2020 Congress
Background: Heparin Induced Thrombocytopenia (HIT) is an immune complication of treatment with heparin, in some cases resulting in life-threatening thrombosis. An accurate diagnosis is required to ensure appropriate clinical decisions are made.
Aims: We describe here a further EQA exercise in which laboratories employing different HIT assays were asked to test and interpret results for a sample from a different donor thought to have HIT based on clinical and laboratory findings.
Methods: Plasma was obtained with informed consent from a patient identified as having HIT antibodies by the Werfen Acustar assay. Plasma was buffered and lyophilised in aliquots and sent to participants in the UK NEQAS for Blood Coagulation (UK NEQAS BC) HIT programme.
Median, coefficient of variation (CV) and range of results were determined for each method and reagent group. Participants were also asked to make an interpretation (positive, equivocal or negative) for the sample.
Results: Results were received from 66 centres. 62% of centres reported a positive screen on the test sample, with 35% reporting a negative screen, and 3% equivocal results. 15/16 centres using ELISA-based assays reported a positive HIT screen, the 12 of which used the Lifecodes/Immucor PF4 IgG kit (median OD 0.72). 13/13 centres using the Werfen Acustar assay reported a positive HIT screen (median 4.09u/ml), compared to just 5/12 using the HemosIL HIT-ab PF4-H kit. 8/14 centres using the Biorad Diamed (ID-PaGIA heparin/PF4 antibody) test and 12/15 centres using the Stago STic Expert kit reported a negative screen. 1 centre reported a positive functional HIPA screen on the sample, and two centres reported heparin neutralisation or inhibition of their assay.
Conclusions: This exercise demonstrated further variability in interpretations for a sample with HIT antibodies, and the need for laboratories and clinicians to understand the clinical implications of reported HIT assay results.
To cite this abstract in AMA style:
Jennings I, Kitchen S, Kitchen D, Munroe-Peart S, Lowe A, Brown L, Walker I. Discrepant Interpretation of HIT Screening Results on the Same Sample – Data from a UK NEQAS for Blood Coagulation Exercise [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/discrepant-interpretation-of-hit-screening-results-on-the-same-sample-data-from-a-uk-neqas-for-blood-coagulation-exercise/. Accessed October 2, 2023.« Back to ISTH 2020 Congress
ISTH Congress Abstracts - https://abstracts.isth.org/abstract/discrepant-interpretation-of-hit-screening-results-on-the-same-sample-data-from-a-uk-neqas-for-blood-coagulation-exercise/