(1735) Assessment of Prophylactic Enoxaparin Dosing in Trauma Patients With Augmented Renal Clearance

Introduction: Trauma patients are at increased risk for venous thromboembolism (VTE) and augmented renal clearance (ARC). Those with ARC may have increased enoxaparin clearance and, as a result, reduced efficacy. Evidence assessing prophylactic weight-based (PPX-WB) enoxaparin in trauma patients with ARC is lacking. Recognizing the potential impact ARC may have on enoxaparin clearance, this study aimed to assess the incidence of subtherapeutic anti-Xa levels (AXA) in trauma patients.

Methods: This retrospective review evaluated trauma patients with ARC, defined as a 12-hour Urinary Measured CrCl (UUN) ≥ 130 mL/min, admitted to University of Utah Hospital (UUH) surgical intensive care unit who received PPX-WB enoxaparin dosed at 0.5 mg/kg and had an AXA collected within 96 hours of meeting ARC criteria. Data was obtained from the UUH electronic data warehouse, EPIC Slicer Dicer, and chart review. The primary outcome was incidence of patients with a subtherapeutic AXA. Secondary outcomes included incidence of patients with therapeutic and supratherapeutic AXA, time from trauma to start of PPX-WB enoxaparin, and incidence of VTE, major bleed, and clinically relevant non-major bleed (CRNMB) while receiving PPX-WB enoxaparin.

Results: A total of 15 patients were included in the analysis with the majority being male (87%). Averages (mean ± SD) for baseline characteristics include: age 33±9 years, ARCTIC score 6.5±1.1, UUN 212.6±74.8 mL/min, enoxaparin dose 45.3±9.9 mg (0.50±0.04 mg/kg), and AXA 0.3±0.1 units/mL. There was 1 incidence of a subtherapeutic AXA and 1 incidence of a supratherapeutic AXA. On average, PPX-WB enoxaparin was started 2.0±0.8 days after the trauma occurred. There was 1 VTE event in the patient with a subtherapeutic AXA. There were 3 cases of major bleeds, all of which met the definition of major bleed due to a hemoglobin drop by >2 g/dL or requiring 2 or more units of packed red blood cells, and 1 case of CNRMB. None of the bleeding events were in the patient with a supratherapeutic AXA.

Conclusions: 6.7% (1/15) of patients with ARC had a subtherapeutic AXA. Enoxaparin clearance may be affected by ARC; however, given the small study size, further analysis is needed to assess the impact of ARC on enoxaparin clearance in trauma patients.