HEP_Score_for_Heparin_Induced_Thrombocytopenia_guideline v.1

The heparin-induced thrombocytopenia expert probability (HEP) score is a tool that can potentially aid in diagnosing patients with suspected HIT, and to avoid expensive HIT workups in some patients. Variables and related values: Thrombocytopenia Features: - Type of heparin-induced thrombocytopenia (HIT) onset suspected: Typical, Rapid. - Magnitude of platelet count fall (Peak to nadir count since heparin): <30%=-1, 30-50%=1, >50%=3. - Timing of fall in platelet count for patients in whom typical onset HIT is suspected: Fall begins <4 days after heparin exposure=-2, Fall begins 4 days after heparin exposure=2, Fall begins 5-10 days after heparin exposure=3, Fall begins 11-14 days after heparin exposure=2, Fall begins >14 days after heparin exposure=-1 - Timing of fall in platelet count for patients in whom rapid (less than 100 days) onset HIT is suspected:Fall begins <4 days after heparin exposure=-2, Fall begins <48 hours after heparin re-exposure=2, Fall begins >48 hours after heparin re-exposure=-1 - Nadir platelet count: ≤20 x 109/L=-2, >20 x 109/L=2 - Thrombosis For patients in whom typical onset HIT is suspected: New VTE or ATE ≥4 days after heparin exposure=3, Progression of pre-existing VTE or ATE while receiving heparin=2 - Thrombosis for patients with prior heparin exposure (last 100 days) and rapid onset HIT is suspected: New VTE or ATE after heparin exposure=3, Progression of pre-existing VTE or ATE while receiving heparin - Skin necrosis at subcutaneous heparin injection sites=3 - Acute systemic reaction after intravenous heparin bolus=2 - Presence of bleeding, petechiae or extensive bruising=-1 Other Causes of Thrombocytopenia: - Presence of chronic thrombocytopenic disorder=-1 - Newly initiated non-heparin medication known to cause thrombocytopenia= -1 - Severe infection=-2 - Severe disseminated intravascular coagulation (DIC) (Fibrinogen <100 mg/dL and D-dimer >5 µg/mL)=-2 - Indwelling intra-arterial device IABP, VAD, ECMO= -2 - Cardiopulmonary bypass within previous 96 hours=-1 - No other apparent cause=3 Interpretation: HEP Scores <2 suggest a lower probability of HIT, HEP Scores ≥2 are 100% sensitive for HIT.

Maryam Razavi

maryam.razavi2009@gmail.com

@CambioCDS

Diagnosing patients with suspected HIT, and to avoid expensive HIT workups in some patients.

In clinical practice, HEP score may be used to diagnose patients with suspected HIT through recording thrombocytopenia features and other causes of thrombocytopenia.

1. Cuker A, Arepally G, Crowther MA, Rice L, Datko F, Hook K, Propert KJ, Kuter DJ, Ortel TL, Konkle BA, Cines DB. The HIT Expert Probability (HEP) Score: a novel pre-test probability model for heparin-induced thrombocytopenia based on broad expert opinion. J Thromb Haemost 2010; 8: 2642–50. 2. Lee Joseph, Gomes MPV, Al Solaiman F, St John J, Ozaki A, Raju M, Dhariwal M, Kim ESH. External Validation Of The HIT Expert Probability (HEP) Score, a Novel Pre-Test Probability Model For Heparin-Induced Thrombocytopenia Based On Broad Expert Opinion. Blood (Impact Factor: 9.06). 12/2013; 122(21):1699.

OBSERVATION.hep_score_for_heparin_induced_thrombocytopenia.v0