Although Heparin-induced thrombocytopenia (HIT) is a rare complication of heparin treatment, it results in a high rate of morbidity and mortality, the cumulative rate of thrombosis recurrence, amputation and death approaching 52 % at one month if no specific treatment is initiated. It is therefore vital to diagnose HIT as early and as reliably as possible to permit appropriate management of this rare condition.

During the acute phase of HIT, clinicians and biologists can only suspect this complication with a greater or lesser degree of confidence. Clinical data are not sufficiently sensitive or specific to confirm or refute thr diagnosis of HIT.

Purpose : To create and validate a score predicting the diagnosis of HIT

Inclusion Criteria:

• all patients presenting, either during or immediately after treatment:

  • thrombocytopenia and/or venous or arterial thrombosis
  • for whom a request for biological assessment to check for HIT (anti-H-PF4 ELISA test) is to be addressed to the specialized haemostasis laboratory participating in the study

Exclusion Criteria:

• do not possess sufficient clinical data prior to performance of the biological test
• cannot assure follow-up of the patient until normalization of the platelet count

community sample