Evaluation of a Reflex Testing Algorithm for Suspected Heparin-Induced Thrombocytopenia

Abstract Objectives We implemented a policy of reflex serotonin-release assay (SRA) testing for all patients with a positive heparin-induced thrombocytopenia (HIT) immunoassay. Methods We identified all patients who had SRA testing sent as a consequence of a positive HIT immunoassay test. We reviewe...

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Bibliographic Details
Published in:American journal of clinical pathology 2017-11, Vol.148 (5), p.390-397
Main Authors: Vanderbilt, Chad M, McFarland, Craig, Lind, Stuart E
Format: Article
Language:English
Subjects:
Algorithms
Anticoagulants
Anticoagulants - adverse effects
Enzyme-linked immunosorbent assay
Hematologic Tests - economics
Hematologic Tests - methods
Heparin
Heparin - adverse effects
Humans
Immune response
Immunoassay
Immunoglobulin G
Optical density
Platelet Activation
Serotonin
Serotonin - metabolism
Side effects
Thrombin
Thrombocytopenia
Thrombocytopenia - diagnosis
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Summary:Abstract Objectives We implemented a policy of reflex serotonin-release assay (SRA) testing for all patients with a positive heparin-induced thrombocytopenia (HIT) immunoassay. Methods We identified all patients who had SRA testing sent as a consequence of a positive HIT immunoassay test. We reviewed charts of patients to calculate the 4Ts clinical score, determined the effect of testing on clinical management, and documented the change in utilization of direct thrombin inhibitors (DTIs). Results The likelihood of a positive SRA varied with the optical density (OD) of the immunoassay. The performance of the immunoglobulin G (IgG)–specific and polytypic enzyme-linked immunosorbent assay was not statistically different. Both OD and 4Ts score correlated with the likelihood of a positive SRA but demonstrated poor specificity. Discontinuation of DTIs in patients with negative SRAs resulted in decreased drug utilization. Conclusions The IgG-specific HIT immunoassay OD correlates with the likelihood of a positive SRA but does not achieve high specificity. The reflex testing algorithm allows for definitive classification of patients, and the cost of such a reflex testing program may be offset by decreased utilization of DTIs.
ISSN:0002-9173
1943-7722
DOI:10.1093/ajcp/aqx078