What is the mortality and morbidity of heparin-induced thrombocytopenia (HIT)?

Updated: Sep 10, 2021
  • Author: Sancar Eke, MD, FASN; Chief Editor: Srikanth Nagalla, MD, MS, FACP  more...
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HIT is a severe prothrombotic condition, with affected individuals having a greater than 50% risk of developing new thromboembolic events. [26] The mortality rate is approximately 20%, and approximately 10% of patients require amputations or suffer other major morbidity. [14, 27, 28]

A consecutive study with 108 hospitalized patients diagnosed with HIT showed that thrombotic complications occurred in about 29%. Early, severe falls in platelet counts in elderly patients receiving heparin appear to be associated with the development of thrombotic complications. [27]

Thrombosis associated with HIT can involve the arterial system, the venous system, or both. Thrombotic complications may include deep venous thrombosisstrokemyocardial infarction, limb ischemia, and, rarely, ischemia of other organs. The thrombotic complications are fatal in about 29% of patients, and an additional 21% have to undergo limb amputations. [29]

Although HIT is a hypercoagulable disorder, patients remain at risk for major bleeding. A review by Pishko et al found that over a third of patients with HIT who were exposed to an alternative anticoagulant experienced a major bleeding event. Factors associated with increased risk of major bleeding included intensive care unit admission, platelet count <  25 × 109 /L, and renal dysfunction. [30]

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