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Semin Thromb Hemost 2014; 40(02): 254-260
DOI: 10.1055/s-0034-1365842
Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Proficiency Testing Results for Heparin-Induced Thrombocytopenia in North America

Kristi J. Smock
1   Department of Pathology and ARUP Laboratories Institute for Clinical and Experiment Pathology, ARUP Laboratories, University of Utah, Salt Lake City, Utah
,
Marlies R. Ledford-Kraemer
2   CLOT-ED, Inc., Islamorada, Florida
,
Piet Meijer
3   ECAT Foundation, Leiden, The Netherlands
,
Peihong Hsu
4   Department of Pathology/Laboratory Medicine, Hofstra North Shore-LIJ School of Medicine, Lake Success, New York
,
Elizabeth M. Van Cott
5   Department of Pathology, Massachusetts General Hospital, Boston, Massachusetts
› Author Affiliations
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Publication History

Publication Date:
04 February 2014 (online)

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Abstract

Between 2010 and 2012, North American Specialized Coagulation Laboratory Association (NASCOLA) distributed five proficiency testing challenges to evaluate laboratory testing for heparin-induced thrombocytopenia (HIT). Results (n = 355) were submitted from 43 unique laboratories for 10 samples (3 positive, 2 weak positive, and 5 negative). The vast majority of results were from commercial enzyme-linked immunosorbent assay (ELISA) methods, predominantly polyvalent assays. Laboratories performed well in the classification of clear negative and positive samples. All results (100%) submitted for the five negative samples (n = 173) and 97% of immunological results submitted for the three positive samples (n = 105) were correctly classified (the incorrect responses were two borderline classifications and, from a gel-agglutination method, one negative classification). There was more difficulty in the classification of the two weak positive samples (n = 70). In one survey, 61% of results from the weak positive sample were classified as positive, while 21% were called negative, 16% were called borderline, and 2% were called inconclusive. In a second survey, 16% of results from the weak positive sample were called positive, while 56% were called negative, and 28% were called borderline. Significant interlaboratory variation was observed for ELISA results, with coefficients of variation of about 20 to 30%. We conclude that there is variability in HIT laboratory testing and that identification of weak positive samples can be challenging.

Keywords

heparin-induced thrombocytopenia - proficiency testing - ELISA - NASCOLA - ECAT