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Multicenter Study
. 2023 Jan-Dec:29:10760296231166370.
doi: 10.1177/10760296231166370.

Evaluation of Latex Immunoturbidimetric Assay Thresholds and HIT in Cardiothoracic Surgery

Jessica Hernandez  1   2   3 , Hetal Patel  2   4 , Phil Biddlecome  2   4 , Megan Kildea  2   4 , Ruti Dwivedi  2   4 , Shashank Sridhara  2   4 , Scott Silvestry  5 , Nicholas Cavarocchi  6 , John L Francis  7 , Davide Ventura  3   4
Affiliations
Multicenter Study

Evaluation of Latex Immunoturbidimetric Assay Thresholds and HIT in Cardiothoracic Surgery

Jessica Hernandez et al. Clin Appl Thromb Hemost. 2023 Jan-Dec.

Erratum in

Abstract

Background: Heparin-induced thrombocytopenia (HIT) is a common differential diagnosis in cardiothoracic surgery. The latex immunoturbidimetric assay (LIA) is an enhanced immunoassay that has recently been introduced for the detection of total HIT immunoglobulin and retains a higher specificity of 95% compared to the enzyme-linked immunosorbent assay.

Objectives: To investigate if a semiquantitative relationship exists between increasing LIA levels beyond the current positivity threshold and its correlation to positive serotonin release assay results in cardiothoracic surgery.

Methods: This was a multicenter, observational cohort of cardiothoracic surgery patients initiated on anticoagulation with heparin-based products. To conduct sensitivity and specificity analysis of LIA values, HIT positive was defined as a LIA value ≥1 unit/mL and HIT negative was defined as a LIA level <1 unit/mL. A receiver operating characteristic (ROC) analysis was utilized to evaluate the predictive performance of the LIA.

Results: At manufactures' cutoffs of ≥1.0 unit/mL, LIA sensitivity and specificity was 93.8% and 22%, respectively, yielding a false positive rate of 78%. At a higher cutoff of 4.5 units/mL, LIA sensitivity and specificity was 75% and 71%, respectively, yielding a false positive rate of 29% and an area under the ROC curve of 0.75 (P = .01; 95% confidence interval: 0.621-0.889). Bivalirudin was initiated in 84.6% of false positive LIA results.

Conclusion: This study suggests that the diagnostic accuracy of the LIA can be optimized by increasing the LIA positivity threshold. Proposing a higher LIA cutoff, may mitigate unwarranted anticoagulation and bleeding outcomes.

Keywords: bioassay; cardiac surgery; heparin-induced thrombocytopenia; immunology.

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Conflict of interest statement

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Figures

Figure 1.
Figure 1.
Institutional HIT diagnostic and treatment pathway. **National Reference Laboratory—ARUP Laboratories: 500 Chipeta Way Salt Lake City, UT, USA. Abbreviations: HIT, heparin-induced thrombocytopenia; LIA, latex immunoturbidimetric assay; SRA, serotonin release assay.
Figure 2.
Figure 2.
LIA AUROC at various LIA cutoffs. Abbreviations: AUROC, area under the receiver operating curve; LIA, latex immunoturbidimetric assay.
See this image and copyright information in PMC

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