Risk Stratification for Supratherapeutic Peak Anti-Xa Levels in Adult Patients on Therapeutic Enoxaparin

Area of Science:

• Pharmacology
• Nephrology
• Critical Care Medicine

Background:

• The American Society of Hematology advises against routine anti-Xa monitoring for enoxaparin due to limited evidence linking supratherapeutic levels to bleeding risk.
• However, anti-Xa monitoring is still used in specific patient groups with altered drug metabolism or excretion.

Purpose of the Study:

• To identify risk factors associated with supratherapeutic peak anti-Xa levels (≥1.10 IU/mL) in patients receiving therapeutic enoxaparin (1 mg/kg twice daily).

Main Methods:

• Retrospective, single-center study at an academic tertiary care hospital.
• Patients receiving enoxaparin 1 mg/kg twice daily with peak anti-Xa monitoring were categorized into supratherapeutic and therapeutic/subtherapeutic groups.
• Univariate and adjusted logistic regression analyses were performed to identify risk factors.

Main Results:

• Obesity (BMI ≥ 30 kg/m²), acute kidney injury (AKI), female sex, intensive care unit (ICU) service, high Sequential Organ Failure Assessment (SOFA) score (≥4), and creatinine clearance were associated with supratherapeutic levels in univariate analysis.
• Adjusted logistic regression identified BMI ≥ 30 kg/m² (OR 4.35-6.75) and AKI (OR 2.62) as significant risk factors for supratherapeutic enoxaparin levels.

Conclusions:

• Body mass index (BMI) ≥ 30 kg/m² and acute kidney injury (AKI) are significant risk factors for supratherapeutic anti-Xa levels in patients on therapeutic enoxaparin.
• Further research is needed to establish a clear association between anti-Xa levels and bleeding risk.