Christopher Coriasso, DO, MS
Critical Care Fellow
Mercy Hospital Saint Louis
Saint Louis, MO, United States
Disclosure information not submitted.
Title: Comparison of HEP and 4Ts Scores for the Diagnosis of Heparin-Induced Thrombocytopenia in the ICU
INTRODUCTION: Thrombocytopenia is common in ICU patients and heparin-induced thrombocytopenia (HIT) is one of the causes. HIT is a potentially fatal adverse drug reaction mediated by platelet-activating antibodies. Several clinical scoring systems have been proposed to help standardize the diagnosis of HIT. The HIT Expert Probability (HEP) score, a novel scoring system, has been designed to overcome the limitations of current scoring systems. The 4Ts score (magnitude of thrombocytopenia, timing of onset of thrombocytopenia, thrombosis or other clinical sequelae, and the likelihood of other causes of thrombocytopenia) has been the most extensively studied and most widely used of these scoring systems. In addition to the 4 domains in the 4Ts score, Hep score includes bleeding and explicit itemization of common other causes of thrombocytopenia. In this study, we aimed to assess the diagnostic accuracy of the HEP score and compare its performance to the 4Ts score in ICU patients.
Methods: A retrospective study of patients suspected of HIT in our ICU from 09/17 to 08/18. Each patient’s HEP score and 4T score was retrospectively calculated. A diagnosis of HIT was considered in patients with both positive ELISA antibodies and positive serotonin-release essay (SRA).
Results: A total of 152 patients were included; HIT was diagnosed in 8 patients (5.3%). At a cutoff of ≥ 3, the HEP score was 75 % sensitive (95% confidence interval [CI], 35 - 97), and 64 % specific (55-72) with a positive predictive value (PPV) of 10 % (7 – 15) and a negative predictive value (NPV) of 98 % (93 – 99) for HIT. A 4Ts score of ≥ 4 had a sensitivity of 100 % (95% CI, 63 - 100), a specificity of 45% (37-54), a PPV of 9 % (8 – 11), and NPV of 100 %. The 4Ts score had a higher area under the receiver operating characteristic (ROC) curves (AUCs) than the HEP score (0.89 +/- 0.10 vs 0.83 +/- 0.07, P = 0.0001). Hep score took about 5 min to calculate vs 2.5 min for the 4Ts score.
Conclusion: In a large community teaching hospital, our data suggest that either the 4Ts score or the
HEP score may be used in ICU patients suspected of HIT. The 4T score showed higher diagnostic accuracy and took shorter time to calculate than the HEP score. These findings should be investigated in large multicenter prospective studies.