OC 57.5 - A new, rapid HISCL HIT IgG Assay Kit offers increased specificity in the diagnosis of heparin-induced thrombocytopenia (HIT)

Tuesday, June 25, 2024

10:30 – 10:45 ICT

Room: 210 A-D

Presenting Author(s)

Annette Bowyer, BSc MSc PhD

Biomedical Scientist
Sheffield Teaching Hospitals
Sheffield, England, United Kingdom

Co-Author(s)

Steve Kitchen

Clinical Scientist
UK NEQAS Blood Coagulation
Sheffield, England, United Kingdom
KK

Katsushi Kobayashi

CEO
Sysmex Corporation
Kobe, Hyogo, Japan
KK

Kiyoko Kohama

Reagent Engineering Manager
Sysmex Corporation
Kobe, Hyogo, Japan
RW

Richard Wardle

Pathology Manager
Sheffield Teaching Hospitals
Sheffield, England, United Kingdom
RH

Ryo Hasegawa

Reagent Engineer
Sysmex Corporation
Kobe, Hyogo, Japan
AM

Ayano Mukaida

Reagent Engineer
Sysmex Corporation
Kobe, Hyogo, Japan
IP

Irfan Patel

Senior Product Specialist
Sysmex UK
Milton Keynes, England, United Kingdom

Background: Heparin-induced thrombocytopenia (HIT) is a potentially fatal complication of unfractionated or low molecular weight heparin therapy that can result in thrombocytopenia and thrombosis. It is caused by the development of IgG antibodies to complexes of platelet factor 4 (PF4) and heparin. Timely diagnosis of HIT is imperative to prevent further morbidity.

Aims: An evaluation of a rapid chemiluminescent enzyme immunoassay (CLEIA), HISCL HIT IgG Assay Kit with Automated Blood Coagulation Analyser CN-6500 was compared with automated and ELISA antibody assays in normal donors, patients suspected of having HIT and other subgroups.

Methods: HISCL HIT IgG, HemosIL AcuStar HIT-IgG (AcuStar), HemosIL HIT-Ab (HIT-Ab), ZYMUTEST HIA IgG and LIFECODES PF4 IgG were used for testing plasmas from 122 normal donors, 133 patients suspected of having HIT and a total of 183 other patients including those in intensive care units (ITU) or containing potentially interfering substances. HIT positive samples were tested by the HIPA functional assay, which was also performed in patients suspected of HIT and any other positive autoantibodies.

Results: False positive HIT results were measured in four normal donors by ELISA and four icteric/lipaemic samples by automated assays. No false positives were measured in these sample groups by HISCL HIT IgG (table 1).
In patients suspected of HIT, 40 were confirmed by HIPA as HIT positive and 93 were HIT negative. Assay sensitivity was 100% for all antibody tests excepted for HIT-Ab (97.5%). Specificity was 77.4% with HISCL HIT IgG whilst for other antibody assays was 62.4-74.2% (table 2).
The time to first result with HISCL HIT IgG was 17 minutes compared to 37 minutes for AcuStar.

Conclusion(s): HISCL HIT IgG is a rapid CLEIA which demonstrated equivalent sensitivity and improved specificity compared to other HIT antibody assays. No false positive results were measured by HISCL HIT IgG in normal donors, ITU or other subgroups.