Utilization of adjusted body weight for dosing unfractionated heparin in obese patients with venous thromboembolism: A retrospective matched cohort study

Purpose: To evaluate the effectiveness of adjusted body weight (AjBW)-based dosing of unfractionated heparin (UFH) in obese patients vis a vis actual body weight (ABW)-based dosing in non-obese patients with venous thromboembolism (VTE). Methods: A retrospective chart review was conducted for obese and non-obese patients initiated on UFH for treating VTE from September 2013 to December 2014. Patients were excluded from the study if they were under 18 years old, developed heparin-induced thrombocytopenia during treatment, received thrombolytic therapy prior to UFH, or received UFH at a dose that did not follow the institution's protocol. The primary objective was to assess the efficacy of dosing UFH based on AjBW in achieving a therapeutic activated partial thromboplastin time (aPTT) within the first 24 h in obese patients, in comparison to the standard ABW-dosing for non-obese. Results: Of the 57 patients included in the study, 27 patients (47.4 %) were obese, and 30 patients (52.6 %) were non-obese; 16 (59.25 %) of the obese patients achieved a therapeutic aPTT within the first 24 h of AjBW-based dosed UFH, while 18 (60 %) of the non-obese patients achieved a therapeutic aPTT within the first 24 h of ABW-based dosed UFH (p = 0.45). Conclusion: AjBW-based dosing of UFH in obese patients demonstrates comparable efficacy to ABW-based dosing in non-obese patients.