Risk of thrombosis in patients with malignancy and heparin-induced thrombocytopenia.

Heparin-induced thrombocytopenia (HIT) is a common immunological drug reaction. After exposure to heparin, some patients develop heparin dependent antibodies with no evidence of thrombosis, while others are at risk of thrombocytopenia, thrombosis, limb loss, and death. We conducted a retrospective chart review on all patients serologically positive for HIT by HPIA ELISA in a single tertiary-care hospital, to determine whether patients with malignancy had an increased risk of thrombotic complications. Medical records of 55 patients who tested positive for HIT and met clinical criteria for HIT were analyzed. All patients had been treated with unfractionated heparin. Malignancy was diagnosed in 11 patients, either at surgery or post-mortem examination. A higher rate of venous thrombosis and pulmonary embolism was observed in patients with HIT and malignant disease when compared to patients with no underlying malignancy (odds ratio 13.6, 95% CI 2.9-63.8).