An international external quality assessment for laboratory diagnosis of heparin‐induced thrombocytopenia
Author(s): ,
Julia J. M. Eekels
Affiliations:
Institut für Immunologie und Transfusionsmedizin, Universitätsmedizin Greifswald, Greifswald, Germany
,
Karina Althaus
Affiliations:
Institut für Immunologie und Transfusionsmedizin, Universitätsmedizin Greifswald, Greifswald, Germany. Transfusion Medicine, Medical Faculty of Tübingen, Tübingen, Germany
,
Tamam Bakchoul
Affiliations:
Transfusion Medicine, Medical Faculty of Tübingen, Tübingen, Germany
,
Hartmut Kroll
Affiliations:
Institute for Transfusion Medicine Dessau, Red Cross Blood Transfusion Service NSTOB, Dessau, Germany
,
Volker Kiefel
Affiliations:
Institut für Transfusionsmedizin, Universitätsmedizin Rostock, Rostock, Germany
,
Ishac Nazy
Affiliations:
Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Canada
,
Lau Soon Lee
Affiliations:
Department of Laboratory Medicine, Tan Tock Seng Hospital, Singapore, Singapore
,
Ulrich Sachs
Affiliations:
Institute for Clinical Immunology and Transfusion Medicine, Justus Liebig University, Giessen, Germany
,
Theodore. E. Warkentin
Affiliations:
Institute for Clinical Immunology and Transfusion Medicine, Justus Liebig University, Giessen, Germany. Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Canada
Andreas Greinacher
Affiliations:
Institut für Immunologie und Transfusionsmedizin, Universitätsmedizin Greifswald, Greifswald, Germany
Correspondence: Andreas Greinacher, Universitätsmedizin Greifswald, Institut für Immunologie und Transfusionsmedizin, Ferdinand‐Sauerbruch‐straße, 17475 Greifswald, Germany|Tel: +49 3834 86 5482|E‐mail: greinach@uni-greifswald.de
ISTH Academy. Greinacher A. Mar 1, 2019; 273409
Prof. Andreas Greinacher
Prof. Andreas Greinacher
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Objective
Heparin‐induced thrombocytopenia (HIT) is a potentially life‐threatening complication of heparin exposure. Diagnosis is most reliable using a combination of an enzyme immunoassay (EIA) that detects antibodies against platelet factor 4 (PF4)/heparin complexes (“antigen” assay) and a “functional” assay that detects platelet‐activating properties of the pathogenic HIT antibodies. No External Quality Assessment (EQA) is available for a combination of the tests. Here we report on the results of the first international EQA.
Methods
The pilot EQA was organized by the Department of Transfusion Medicine, Universitätsmedizin Greifswald, Germany. Six serum samples of patients, which were referred to Greifswald for HIT diagnosis, and one negative control sample were distributed to seven participants in Germany, Canada, and Singapore. Participants were asked to report the optical density (OD) values of their local EIA test for IgG‐specific antibodies against the PF4/heparin complexes and the results for a functional assay (HIPA or SRA). Consensus was defined as a minimum 70% agreement, i.e., agreement among at least five of the seven participating laboratories.
Results and conclusion
Six out of seven participants reported results for EIA, with a high quantitative accordance (97.6%). For the functional assay, consensus was reached for all samples except the negative control, for which some participants reported nonspecific reactivity. All HIT‐negative samples were correctly diagnosed by all participants; for HIT‐positive samples, consensus of 70% was reached. Although the limited availability of sample material is an obstacle to overcome, an EQA combining both EIA and functional testing is feasible.
Keyword(s)
blood platelets, heparin, laboratory proficiency testing, platelet factor 4, thrombocytopenia
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