PB0350 - Prospective Study to Evaluate the Consolidated Performance of Two Automated Rapid Assays for the Diagnosis of Heparin-induced Thrombocytopenia

Sunday, June 25, 2023

18:30 – 19:30 ET

Room: Exhibition

Co-Author(s)

AB

Anna-Lise Bissola, MSc (she/her/hers)

Research Associate
Faculty of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
Hamilton, Ontario, Canada

Presenting Author(s)

Yi Zhang (she/her/hers)

MSc Candidate
Department of Biochemistry and Biomedical Sciences, McMaster University Hamilton, Ontario, Canada
Hamilton, Ontario, Canada

Co-Author(s)

JM

Jane Moore

Assistant Professor
Faculty of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
Hamilton, Ontario, Canada
NI

Nikola Ivetic

Postdoctoral Fellow
Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
Hamilton, Ontario, Canada
HB

Hina Bhakta

Research Technician
Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
Hamilton, Ontario, Canada
RC

Rumi Clare

Research Associate
Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
Hamilton, Ontario, Canada
JK

John G. Kelton

Professor
Faculty of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
Hamilton, Ontario, Canada
Donald Arnold, MD MSc (he/him/his)

Professor
McMaster University, Department of Medicine
HAMILTON, Ontario, Canada
Ishac Nazy, PhD

Associate Professor
Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada,
Hamilton, Ontario, Canada

Background: Most diagnostic laboratory enzyme immunoassays (EIA) for heparin-induced thrombocytopenia (HIT) are excellent for "ruling-out" HIT but suffer from reduced specificities. Alternatively, functional platelet-activation assays, including the 14C-serotonin release assay (SRA), offer better specificity and higher sensitivity, but are technically challenging to perform and require donor platelets. Rapid automatic assays for HIT may offer a solution to these diagnostic limitations, however, further practical evaluations of these assays are still needed.

Aims: This study compared the performances of latex immunoturbidimetric assay (LIA) and chemiluminescence immunoassay (CLIA), either alone or together, to identify platelet activating anti-PF4/heparin antibodies in a prospective cohort of patients with clinically suspected HIT.

Methods: A total of 1694 unique patient serum and/or plasma samples were collected between December 2018 and August 2020 based on a clinical suspicion of HIT. Based on sample avalibility, patients were tested in a commercial LIA (HemosIL®HIT-Ab(PF4-H)], n=756), CLIA ([HemosIL®AcuStarHIT-Ab(PF4-H)], n=1008), or both (n=541) according to manufacturer's instructions. The performance characteristics of each test was then determined against the standard SRA.

Results: Using the standard SRA as a reference, we determined the preliminary performance characteristics of the commercial LIA (sensitivity 91.4%, specificity 64.6%), CLIA (sensitivity 92.1%, specificity 83.1%), and an integrated LIA-CLIA algorithm (sensitivity 97.8%, specificity of 85.8%).

Conclusion(s): Compared to individual LIA or CLIA testing, an integrated LIA-CLIA testing algorithm showed improved diagnostic sensitivity (97.8%) and specificity (85.8%). These results further support using the LIA and CLIA in tandem to diagnose HIT to supplement platelet-activation assays if both instruments are avaliable. Moreover, our study found a slight reduction in both sensitivity and specificity compared to previous reports that used a retrospective cohort of prescreened suspected HIT patients. We demonstrate prospective studies accounting for clinician variability may more accurately evaluate the real-world performance of HIT diagnostic tests.