Differences in the clinical course of heparin induced thrombocytopenia before and after the availability of HIT IgG...

To determine whether the HIT IgG class platelet factor 4 (PF4) enzyme immunoabsorbant assay (EIA) influenced the duration of parenteral direct thrombin inhibitor (pDTI) therapy or bleeding risk in patients started on pDTI for a presumed diagnosis of HIT.

187 patients started on pDTI for presumed HIT were assessed in two time periods before (period 1, n=88 patients) and after the introduction of an IgG-specific assay (period 2, n=99 patients).

Patients in period 2 were treated with pDTI therapy for a median of 5 days less (p<0.0001) however the incidence of Grade III and IV bleeding episodes was not different. Bleeding was observed to occur early during the hospital course at a median of 2-3 days after initiation of the pDTI. The average pDTI drug acquisition cost was markedly decreased in period 2 when compared to period 1 (p<0.0001).

Implementation of the IgG class HIT EIA resulted in a decrease in the number of days on a pDTI and a decrease in the average pDTI acquisition cost per patient without an observed change in serious bleeding events.