Prospective evaluation of the ‘4Ts’ score and particle gel immunoassay specific to heparin/PF4 for the diagnosis of heparin‐induced thrombocytopenia

Background: Heparin‐induced thrombocytopenia (HIT) is a severe disease that is often difficult to diagnose. A clinical scoring system, the ‘4Ts’ score, has been proposed to estimate its probability before laboratory testing, and a particle gel immunoassay (H/PF4 PaGIA®) has also been developed for r...

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Bibliographic Details
Published in:Journal of thrombosis and haemostasis 2007-07, Vol.5 (7), p.1373-1379
Main Authors: POUPLARD, C., GUERET, P., FOUASSIER, M., TERNISIEN, C., TROSSAERT, M., RÉGINA, S., GRUEL, Y.
Format: Article
Language:English
Subjects:
4Ts score
Adolescent
Adult
Aged
Aged, 80 and over
Antigen-Antibody Complex - blood
Autoantibodies - blood
Drug Hypersensitivity - blood
Drug Hypersensitivity - diagnosis
Drug Hypersensitivity - etiology
Drug Hypersensitivity - immunology
Female
heparin
Heparin - adverse effects
Heparin - immunology
Humans
Immunoassay - methods
Immunoassay - statistics & numerical data
Immunoglobulin G - blood
Male
Middle Aged
particle gel immunoassay
Platelet Factor 4 - immunology
Platelet Factor 4 - metabolism
Predictive Value of Tests
Prospective Studies
Purpura, Thrombocytopenic, Idiopathic - blood
Purpura, Thrombocytopenic, Idiopathic - diagnosis
Purpura, Thrombocytopenic, Idiopathic - etiology
Purpura, Thrombocytopenic, Idiopathic - immunology
Sensitivity and Specificity
thrombocytopenia
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Summary:Background: Heparin‐induced thrombocytopenia (HIT) is a severe disease that is often difficult to diagnose. A clinical scoring system, the ‘4Ts’ score, has been proposed to estimate its probability before laboratory testing, and a particle gel immunoassay (H/PF4 PaGIA®) has also been developed for rapid detection of HIT antibodies. Aim: To evaluate the performance of both methods when HIT is suspected clinically. Methods: Two hundred thirteen consecutive patients were included in four centers. The probability of HIT was evaluated using the 4Ts score blind to antibody test results. HIT was confirmed only when the serotonin release assay (SRA) was positive. Results: The risk of HIT was evaluated by the 4Ts score as low (LowR), intermediate (IR) or high (HR) in 34.7%, 60.6% and 4.7% of patients, respectively. The negative predictive value (NPV) of the 4Ts score was 100%, as the SRA was negative in all LowR patients. PaGIA® was negative in 176 patients without HIT (99.4%, NPV) and the negative likelihood ratio (LR–) was 0.05. PaGIA® was positive in 37 patients, including 21 with HIT (positive predictive value = 56.8%), with a positive LR of 11.4. A negative PaGIA® result decreased the probability of HIT in IR patients from 10.9% before assay to 0.6%, whereas a positive result did not substantially increase the likelihood for HIT. Conclusion: The use of the 4Ts score with PaGIA® appears to be a reliable strategy to rule out HIT.
ISSN:1538-7933
1538-7836
1538-7836
DOI:10.1111/j.1538-7836.2007.02524.x