Safety of High-Dose Unfractionated Heparin for Prophylaxis of Venous Thromboembolism in Hospitalized Obese Patients

Abstract

Background Optimal dosing of unfractionated heparin (UFH) for thromboprophylaxis in the obese patient population is uncertain because of their high-risk, prothrombotic state and a complexity of pharmacokinetic considerations. Literature on the appropriateness of the use of a higher dose UFH regimen remains unclear and inconsistent. Objective To evaluate the safety of the use of 7500 units every 8 hours ( high-dose) of subcutaneous UFH compared with the use of 5000 units every 8 hours ( standard-dose) of subcutaneous UFH for thromboprophylaxis in obese patients (defined as BMI ≥30 kg/m2). Methods In a retrospective cohort study, 326 adult patients were included, with a BMI ≥30 kg/m2, who were admitted to a large, urban academic medical center between September 1, 2015, and September 1, 2018. Patients received either high-dose or standard-dose UFH for at least 48 hours. The primary end point was the incidence rate of bleeding events, defined as a ≥2-g/dL fall in hemoglobin level or receipt of transfusion of 2 or more units of packed red blood cells (pRBCs) from the start of the UFH order. Results The incidence rate of bleeding was significantly higher in those who received high-dose UFH (43%) compared with those who received standard-dose UFH (29%; P = 0.008). No significant difference was found between venous thromboembolism event rates. Conclusion and Relevance High-dose UFH was associated with an increased bleeding event rate compared with standard-dose UFH in patients with a BMI ≥30 kg/m2. This raises safety concerns about the appropriateness of utilizing this regimen in this population.