To cite this article: Pouplard C, Gueret P, Fouassier M, Ternisien C, Trossaert M, Ré gina S, Gruel Y. Prospective evaluation of the Ô4TsÕ score and particle gel immunoassay specific to heparin/PF4 for the diagnosis of heparin-induced thrombocytopenia. J Thromb Haemost 2007; 5: 1373-9.See also Arnold DM, Kelton JG. Testing for heparin-induced thrombocytopenia: are we there yet? This issue, pp 1371-2.Summary. Background: Heparin-induced thrombocytopenia (HIT) is a severe disease that is often difficult to diagnose. A clinical scoring system, the Ô4TsÕ score, has been proposed to estimate its probability before laboratory testing, and a particle gel immunoassay (H/PF4 PaGIA Ò ) 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 Ò was negative in 176 patients without HIT (99.4%, NPV) and the negative likelihood ratio (LR-) was 0.05. PaGIA Ò was positive in 37 patients, including 21 with HIT (positive predictive value = 56.8%), with a positive LR of 11.4. A negative PaGIA Ò 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 Ò appears to be a reliable strategy to rule out HIT.

Calibrated Automated Thrombography (CAT) has been widely used to assess in vitro thrombin generation as an informative intermediary phenotype of coagulation. Interlaboratory exercises have documented a worrisome poor reproducibility. There are some data on the normalisation with an appropriate external reference plasma (RP). This multicentre study of the French-speaking CAT Club aimed at providing further evidence for the usefulness of such a normalisation

With this new dual-color flow cytometric method, accurate evaluation of fetomaternal hemorrhage was achieved even in the face of HbF of maternal origin.

Oral doses of ACT-281959 and ACT-246475 were well tolerated. Platelet inhibition correlated with ACT-246475 exposure. Exploratory formulations enhanced the bioavailability and antiplatelet effect of ACT-246475.

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