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Evaluation of Latex Immunoturbidimetric Assay Thresholds and HIT in Cardiothoracic Surgery
Hernandez, Jessica Patel, Hetal Biddlecome, Phil Kildea, Megan Dwivedi, Ruti Sridhara, Shashank Silvestry, Scott Cavarocchi, Nicholas Francis, John L. Ventura, Davide
Hernandez, Jessica
Patel, Hetal
Biddlecome, Phil
Kildea, Megan
Dwivedi, Ruti
Sridhara, Shashank
Silvestry, Scott
Cavarocchi, Nicholas
Francis, John L.
Ventura, Davide
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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.
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Date
2023-04-17
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SAGE Publications
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Keywords
Heparin-induced thrombocytopenia, Immunology, Cardiac surgery, Bioassay
Citation
Hernandez J, Patel H, Biddlecome P, et al. Evaluation of Latex Immunoturbidimetric Assay Thresholds and HIT in Cardiothoracic Surgery. Clinical and Applied Thrombosis/Hemostasis. 2023;29. doi: 10.1177/10760296231166370