Diagnosing Heparin-Induced Thrombocytopenia: How Accurate Is the Recommended Algorithm?

Heparin-induced thrombocytopenia (HIT) is a high-risk condition that requires immediate therapy with high-risk medications; thus, accurate diagnosis is critical. Because HIT-antibody testing has a relatively high false-positive rate, guidelines direct clinicians to use an algorithm that starts with the 4Ts score and then recommends antibody testing in patients whose 4Ts scores indicate intermediate or high risk for HIT. In this prospective study of 1300 patients with possible HIT, investigators assessed the accuracy of the 4Ts score and the guideline-recommended diagnostic algorithm. The reference-standard test for comparison was a heparin-induced platelet activation assay; prevalence of HIT was 8.4% by reference-standard testing.

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