Heparin-induced thrombocytopenia (HIT): Clinical and economic outcomes

Heparin-induced thrombocytopenia (HIT) is an immune-mediated adverse drug reaction that occurs following exposure to unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH). HIT with thrombosis (HITT) can cause devastating venous thromboembolism or arterial clots, prolonged hospitalization, and increased costs. To explore the economic and clinical implications of HIT and HITT, we initiated a single-center patient registry. In this report, we describe patient characteristics, comorbidities, management strategies, clinical outcomes, and costs. We enrolled 349 hospitalized patients with an enzyme immunoassay-confirmed diagnosis of HIT over a 40-month period. Patients were assessed for the primary outcome of 30-day mortality, as well as baseline characteristics, development of throm-bosis, and the economic impact of HIT. The primary outcome measure was 30-day mortality and occurred in 58 (16.6%) patients, 40 (15.3%) in the HIT group versus 18 (20.7%) in the HITT group (p=0.25). The frequency of HIT was greater in patients exposed to UFH than in patients exposed to LMWH (0.8% vs. 0.2%, respectively, p<0.001). Both HIT and HITT patients who were exposed to UFH had higher hospital costs than those exposed to LMWH ($113, 100 vs. $56,352, respectively, p<0.001). HIT remains an important clinical problem with a high mortality rate and significant cost, regardless of development of thrombosis. Prospective controlled trials need to be conducted to determine the optimal strategy to reduce the frequency of HIT.