Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2025 Apr;58(4):556-565.
doi: 10.1007/s11239-025-03097-z. Epub 2025 Apr 5.

Evaluation of unfractionated heparin dosing using an antifactor-Xa-based protocol in non-obese vs. obese patients for acute venous thromboembolism

Trenton Flanagan  1 , Monica Sharma  2 , Uyen-Thi Cao  3   4 , Xuan Wang  5 , Vivek Kataria  2
Affiliations

Evaluation of unfractionated heparin dosing using an antifactor-Xa-based protocol in non-obese vs. obese patients for acute venous thromboembolism

Trenton Flanagan et al. J Thromb Thrombolysis. 2025 Apr.

Abstract

The pharmacokinetic profile of heparin may result in supratherapeutic antifactor-Xa levels using total weight-based protocols for the treatment of venous thromboembolism (VTE) in obese patients. Previous literature has been limited by choice of monitoring assay and inconsistent dosing strategies. The goal of this study was to evaluate safety and efficacy outcomes of an antifactor-Xa based UFH VTE protocol in obese vs. non-obese patients. This was a single center, retrospective study of adult patients with an acute VTE treated with our institution specific UFH VTE protocol. Patients were screened from the preceding 3 years for inclusion into the obese (BMI ≥ 30 kg/m2) or non-obese (BMI < 30 kg/m2) groups. The primary outcome was the weight-based rate of UFH (units/kg/hr) required to attain a therapeutic anti-Xa level. Secondary outcomes included rate required to attain steady state, time to first therapeutic anti-Xa level and steady state, proportion of patients to attain at least one therapeutic anti-Xa level and steady state, number of rate changes required to attain steady state, and proportion of anti-Xa levels being therapeutic, subtherapeutic, or supratherapeutic at the first anti-Xa level drawn, within the first 24 h of treatment, and for the duration of treatment with UFH. Safety outcomes evaluated the incidence of any major or non-major bleeding event, requiring reversal agents, or having additional thrombotic events. The primary outcome of weight-based rate at first therapeutic anti-Xa level was significantly lower in the obese group, and this was consistent for attainment of steady state, as well (14 units/kg/hour vs. 16 units/kg/hour, p < 0.001). Patients in the obese group had significantly more supratherapeutic anti-Xa levels within 24 h (50% vs. 33%, p < 0.0001) and for the total duration of UFH therapy (40% vs. 25%, p < 0.0001) No significant differences in clinically overt bleeding rates were found. Obese patients required a lower weight-based rate of UFH to attain therapeutic anti-Xa levels for the treatment of VTE. Additionally, there appears to be an inverse relationship between weight-based UFH rate and total UFH rate at the first therapeutic anti-Xa and steady state as BMI increases. Future studies should focus on dosing strategies that improve attainment of therapeutic anti-Xa levels in obese patients.

Keywords: Anticoagulation; Antifactor-Xa; Heparin; Obesity; Venous thromboembolism.

PubMed Disclaimer

Conflict of interest statement

Declarations. Competing interests: The authors have no competing interests to declare that are relevant to the content of this article. The authors did not receive support from any organization for the submitted work. Research involving human and animal participants: This retrospective chart review study involving human participants was in accordance with the ethical standards of the institutional research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical Standards. Approval was obtained from the Institutional Review Board of the Baylor Research Institute.

Similar articles

See all similar articles

References

    1. Bell EJ, Lutsey PL, Basu S et al (2016) Lifetime risk of venous thromboembolism in two cohort studies. Am J Med. https://doi.org/10.1016/j.amjmed.2015.10.014 - DOI - PubMed - PMC
    1. Goldhaber SZ (2010) Risk factors for venous thromboembolism. J Am Coll Cardiol 56(1):1–7. https://doi.org/10.1016/j.jacc.2010.01.057 - DOI - PubMed
    1. Puurunen MK, Gona PN, Larson MG, Murabito JM, Magnani JW, O’Donnell CJ (2016) Epidemiology of venous thromboembolism in the Framingham Heart Study. Thromb Res 145:27–33. https://doi.org/10.1016/j.thromres.2016.06.033 - DOI - PubMed - PMC
    1. Eichinger S, Hron G, Bialonczyk C et al (2008) Overweight, obesity, and the risk of recurrent venous thromboembolism. Arch Intern Med 168(15):1678–1683. https://doi.org/10.1001/archinte.168.15.1678 - DOI - PubMed
    1. Harris E (2023) US obesity prevalence surged over the past decade. JAMA 330(16):1515. https://doi.org/10.1001/jama.2023.19201 - DOI - PubMed

MeSH terms

LinkOut - more resources