Stratifying Therapeutic Enoxaparin Dose in Morbidly Obese Patients by BMI Class: A Retrospective Cohort Study
Enoxaparin is a low-molecular weight heparin (LMWH) commonly used for treatment of venous thromboembolism and acute coronary syndromes. The recommended dose for these conditions is weight-based (1 mg/kg) and doesn’t require dose-capping. However, previous studies have shown that in those with a body mass index (BMI) > 40 kg/m2, this dose results in supratherapeutic levels.
This study investigated enoxaparin dosing in morbidly obese patients with a goal of identifying a dose with the greatest chance of producing favorable anti-factor Xa (anti-Xa) levels.
This retrospective cohort study by electronic chart review was used to record data of patients who received enoxaparin with anti-Xa level monitoring between 2012 and 2017. The primary outcome was the enoxaparin dose that results in a therapeutic anti-Xa level (0.5–1.0 IU/mL) among three BMI groups. Secondary outcomes were bleeding and thromboembolic events.
Two hundred forty-one patients were included in the study, and 132 achieved a therapeutic dose. For those with a BMI of 40–50 kg/m2, the median therapeutic dose was 0.97 mg/kg every 12 h. In subjects with a BMI of 50–60 kg/m2, the median therapeutic dose was 0.70 mg/kg. Finally, the median therapeutic dose for subjects with a BMI over 60 kg/m2 was 0.71 mg/kg. In all three groups, 53–65% of patients had a supratherapeutic anti-Xa level while less than 10% had a subtherapeutic level. Relatively few patients (4.1%) experienced major bleeding and only one thromboembolic event was reported.
Standard dosing of enoxaparin in morbidly obese patients will most likely lead to supratherapeutic anti-Xa levels and thus further investigation is warranted to better determine appropriate dosing.
The authors wish to acknowledge the contribution of the Texas Tech University Health Sciences Center Clinical Research Institute for their assistance with this research.
Compliance with Ethical Standards
No funding was received in relation to the conduct of this study.
Conflict of interest
Young R. Lee, Peter J. Palmere, Caitlin E. Burton, and Taylor M. Benavides declare that they have no conflict of interest.
For this type of study, formal consent is not required.
Our study was reviewed and approved by the Texas Tech University Health Sciences Center Institutional Review Board.
- 1.World Health Organization. Obesity and overweight. Updated February 2018. https://www.who.int/news-room/fact-sheets/detail/obesity-and-overweight. Accessed 19 Apr 2019.
- 2.Centers for Disease Control and Prevention. Adult obesity facts. Updated August 2018. https://www.cdc.gov/obesity/data/adult.html. Accessed 19 Apr 2019.
- 3.Lovenox [package insert]. Bridgewater: Sanofi-Aventis U.S.; 2013.Google Scholar
- 9.Deal EN, Hollands JM, Riney JN, Skrupky LP, Smith JR, Reichley RM. Evaluation of therapeutic anticoagulation with enoxaparin and associated anti-Xa monitoring in patients with morbid obesity: a case series. J Thromb Thrombolysis. 2011;32:188–94. https://doi.org/10.1007/s11239-011-0584-7.CrossRefPubMedGoogle Scholar
- 10.Garcia DA, Baglin TP, Weitz JI, Samama MM. Parenteral anticoagulants: antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines. Chest. 2012;141(2 suppl):e24S–43S. https://doi.org/10.1378/chest.11-2291.CrossRefPubMedPubMedCentralGoogle Scholar
- 12.Nutescu EA, Spinler SA, Wittkowsky A, Dager WE. Low-molecular-weight heparins in renal impairment and obesity: available evidence and clinical practice recommendations across medical and surgical settings. Ann Pharmacother. 2009;43(6):1064–83. https://doi.org/10.1345/aph.1L194.CrossRefPubMedGoogle Scholar
- 13.Schulman S, Kearon C, Subcommittee on Control of Anticoagulation of the Scientific and Standardization Committee of the International Society on Thrombosis and Haemostasis. Definition of major bleeding in clinical investigations of antihemostatic medicinal products in non-surgical patients. J Thromb Haemost. 2005;3(4):692–4.CrossRefGoogle Scholar