PB0787 - Concordance of Low Molecular Weight and Unfractionated Heparin Serotonin Release Assays

Monday, June 26, 2023

18:30 – 19:30 ET

Room: Exhibition

Presenting Author(s)

Edward Wong, MD

Medical Director, Coagulation
Quest Diagnostics
Secaucus, New Jersey, United States

Co-Author(s)

MS

Mervyn Sahud

Consultant
Quest Diagnostics
Chantilly, Virginia, United States
JD

Jeffrey Dlott

Consultant
Quest Diagnostics
Chantilly, Virginia, United States
BW

Bin Wei

Scientific Director
Quest Diagnostics
Chantilly, Virginia, United States
MS

Michael Stepanian

Manager
Quest Diagnostics
Chantilly, Virginia, United States
LN

Lina Noh

Data analyst/Administrative Assistant
Quest Diagnostics
Chantilly, Virginia, United States
LW

Laura Worfolk, PhD

Scientific Director, Coagulation
Quest Diagnostics, Virginia, United States
Fr

Frederick racke

Medical Director
Quest Diagnostics
San Juan Capistrano, California, United States

Background: Heparin-induced thrombocytopenia (HIT) is typically due to the development of an IgG antibody to a neoantigen upon exposure to unfractionated heparin (UFH) or low molecular weight heparin (LMWH) that can cause platelet activation and subsequent thrombosis. Functional detection of these antibodies can be determined using a UFH or LMWH 14C-serotonin release assay (SRA). However, little is known of the concordance of LMWH and UFH SRA and whether distinguishing antibodies to either LMWH or to UFH is important.

Aims: To determine the concordance rate of HIT antibodies due to LMWH or UFH

Methods: 10-year retrospective review of results from samples tested for both LMWH and UFH 14C-SRA release testing from 2012 to 2021. Serotonin release testing was performed as described by Sheridan et al. Blood. 1986;67:17-30. Concordance was defined as the same qualitative results (positive, indeterminate, or negative) for both LMWH and UFH SRA testing. Concordance was stratified by result.

Results: A total of 1,420 patient results were evaluated. The median (5th and 95th percentiles) yearly number of patients tested for both LMWH and UFH SRA was 147 (99 and 184). Yearly median overall (positive, indeterminate, and negative) concordance rate was 92.7% (85.5% and 95.6%). In contrast, yearly median overall for any discordance was 7.3% (4.4% and 14.5%). The yearly median major (negative vs positive or vice versa) discordance rate was 2.7% (1.1% and 6.4%). Of the major discordance results over the10-year period, positive LMWH/negative UFH SRA results were 2 to 3 times higher than positive UFH/negative SRA results.

Conclusion(s): A high percentage (>90%) of LMWH and UFH SRA test results were concordant. In contrast, a small percentage ( < 3%) of test results demonstrated major discordance. Further study is needed to correlate administration of UFH vs LMWH with testing results and determine whether either or both types of SRA testing are needed.