Incidence and economic implications of heparin-induced thrombocytopenia in medical patients receiving prophylaxis for venous thromboembolism.

Study Objectives: To determine the incidence of heparin-induced thrombocytopenia (HIT) in patients admitted to a medical service who were given unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH) to prevent venous thromboembolism, the incremental cost of developing HIT, and the cost consequences of using LMWH to prevent venous thromboembolism in medical patients.

Design: Retrospective analysis with a nested case-control.

Setting: University-affiliated tertiary-care hospital.

Patients: A total of 10,121 adult medical patients admitted between August 1, 2000, and November 2, 2004, received UFH or LMWH to prevent venous thromboembolism during their admission. From these, patients with immune-mediated HIT were identified and served as case patients, and 3-5 matched control patients were identified for each case patient.

Measurements And Main Results: The development of HIT was determined for patients who received LMWH and for patients who received UFH. Costs were compared between the patients with HIT and the matched control patients. The cost of using LMWH to prevent venous thromboembolism was compared with the cost of using UFH. In patients receiving UFH and those receiving LMWH, the incidence of HIT was 0.51% (43/8420) and 0.084% (1/1189), respectively (p=0.037), with an overall incidence of 0.43% (44/10,121). Admissions that included development of HIT incurred an average cost of 56,364 dollars compared with 15,231 dollars (p<0.001) for admissions without HIT. Using LMWH to prevent venous thromboembolism in medical patients cost 13.88 dollars less per patient than using UFH.

Conclusions: For the prophylaxis of venous thromboembolism, LMWH was associated with a lower incidence of HIT than UFH in medical patients. An admission during which the patient develops HIT costs significantly more than an admission during which the patient does not develop HIT. Low-molecular-weight heparin is cost-effective for prevention of venous thromboembolism in medical patients.