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Thromb Haemost
DOI: 10.1055/a-2791-6535
Original Article: Stroke, Systemic or Venous Thromboembolism

Evaluation of Prophylactic Enoxaparin Anti-Xa Levels in Individuals ≥150 kg

Authors

  • Logan M. Olson

    1   Department of Pharmacy, Nebraska Medicine, Omaha, Nebraska, United States

  • Shelby R. Wells

    1   Department of Pharmacy, Nebraska Medicine, Omaha, Nebraska, United States

  • William J. Peppard

    2   Department of Pharmacy, Froedtert and the Medical College of Wisconsin, Milwaukee, Wisconsin, United States

  • Bradley J. Peters

    3   Department of Pharmacy, Mayo Clinic Rochester, Rochester, Minnesota, United States

  • Elizabeth R. Lyden

    4   Department of Biostatistics, University of Nebraska Medical Center, Omaha, Nebraska, United States

  • Emily F. Cantrell

    5   Department of Surgery, University of Nebraska Medical Center, Omaha, Nebraska, United States
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Graphical Abstract

Abstract

Background

Optimal dosing of prophylactic enoxaparin for individuals ≥150 kg is unknown due to limited inclusion in previous studies.

Objective

Estimate an optimal weight-based prophylactic enoxaparin dose for individuals ≥150 kg.

Patients/Methods

This multicenter, retrospective study included ≥150 kg adult patients admitted to the hospital between January 2014 and April 2024, who received twice daily prophylactic enoxaparin (goal peak anti-Xa 0.2–0.4 IU/mL). At least one peak anti-Xa was required, obtained 3 to 5 hours after the 3rd consecutive dose. The primary outcome was the range of dosing that produced goal prophylactic peak anti-Xa following linear regression modeling. Secondary outcomes were hospital and intensive care unit (ICU)/progressive care unit (PCU) length of stay (LOS), in-hospital mortality, and VTE/bleed events within 72 hours after an eligible peak anti-Xa.

Results and Conclusion

A total of 311 encounters and 388 peak anti-Xa levels were assessed. Patients were 46 (37–55) years old, 53.1% were male, and weighed 183.3 kg (166.1–204.1) with a BMI of 61.3 kg/m2 (54.8–69.4). Creatinine clearance was 179.6 mL/min (126.5–228.2) and patients received 4 doses (4–6) before peak anti-Xa, with a time between of 249 minutes (227–271). Linear regression modeling revealed a statistically significant correlation (r2 = 0.27) between weight-based dose and peak anti-Xa (p < 0.0001). Enoxaparin 0.34 mg/kg (95% CI 0.33–0.36) twice daily was predicted to achieve a peak anti-Xa of 0.3 IU/mL. Hospital LOS was 8 days (4–15), ICU/PCU LOS was 8 days (4–14, n = 158), and only two patients (0.6%) died during hospitalization. One VTE event was observed. Our results suggest an appropriate empiric weight-based prophylactic enoxaparin dose for hospitalized patients ≥150 kg is 0.34 mg/kg twice daily.

Keywords

anti-factor Xa - deep vein thrombosis - dosing - low-molecular-weight heparins - obesity


Publication History

Received: 02 December 2025

Accepted after revision: 18 January 2026

Article published online:
28 January 2026

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