Evaluation of weight based enoxaparin dosing on anti-Xa concentrations in patients with obesity
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Current treatment dose of enoxaparin is based on total body weight (TBW), however dosage in obesity remains unclear. “Dose capping” commonly occurs if TBW > 100 kg minimising bleeding risk. However, this may result in under-dosing and increasing embolisation risk. The primary objective evaluated efficacy of current dosing strategies in obese patients and determined if resultant anti-Xa concentrations (aXaC) were therapeutic. The secondary objective was to investigate if an uncapped 0.75–0.85 mg/kg (TBW) twice daily dose, advocated by previous authors, results in therapeutic aXaC (0.5–1.0 IU/ml). This retrospective study included 133 patients with a median TBW of 128 kg, producing 59% therapeutic, 15% sub-therapeutic and 26% supra-therapeutic aXaC. Approximately 60% of patients in each dose group (< 0.75, 0.75–0.85 and > 0.85 mg/kg) had a therapeutic aXaC, however the percentage of sub-therapeutic versus supra-therapeutic was higher in the < 0.75 (27% vs 9%) and > 0.85 mg/kg (10% vs 34%) groups respectively. Most patients who weighed 100–119 kg (TBW) received doses > 0.85 mg/kg, however 32% had toxic aXaC. Those between 120 and 139 kg (TBW) had a high percentage of therapeutic aXaC (87%) when dosed < 0.75 mg/kg and a high percentage of supra-therapeutic aXaC (71%) when dosed > 0.85 mg/kg; although numbers were low. Dose reduction occurred in patients > 140 kg (TBW), however < 0.75 mg/kg resulted in higher percentage of sub-therapeutic aXaC (42%). Dosing at 0.75–0.85 mg/kg results in 62% of therapeutic, 14% sub-therapeutic and 24% supra-therapeutic aXaC. This appears to be a “safe” starting dose-range, however all obese patients should have aXaC monitoring due to high inter-patient variability.
KeywordsEnoxaparin Low-molecular weight heparin Obesity Morbid obesity Anticoagulation Anti-Xa
Compliance with ethical standards
Conflict of interest
The authors declare they have no conflict of interest.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. This study was also approved by the Human Research Ethics Committee (Reference Number: HREC/16/QWMS/23).
A waiver of consent was granted for this project by the Human Research Ethics Committee.
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