Imputability of heparin in heparin induced thrombocytopenia: a 10 year experience of the Centre Regional de Pharmacovigilance of Reims-Champagne Ardenne.

The imputability of heparin in heparin induced thrombocytopenia (HIT) was analysed retrospectively in the chart records of 86 cases documented by the Centre Regional de Pharmacovigilance (CRPV) of Reims-Champagne Ardenne over a period of 10 years. Considerable difficulties are encountered in evaluating the degree of imputability. Chronological criteria seem to be determinant in the final imputability score, whereas semiological criteria are particularly difficult to interpret, especially as it is not yet clearly established whether biological tests should be taken into account. The method of assessment requires more precise adaptation to the specific case of HIT and could be improved by redefinition of the criteria in collaboration between pharmacologists and haematologists.