748: EVALUATION OF ANTI-XA TARGET ATTAINMENT WITH PROPHYLACTIC ENOXAPARIN DOSING REGIMENS IN OBESITY

Abstract

Introduction: Venous thromboembolism (VTE) is a common complication among hospitalized patients, especially among the critically ill. Obesity doubles the risk of a patient experiencing a VTE event during their hospitalization. To combat this increased risk pharmacologic prophylaxis with enoxaparin is commonly utilized. The optimal dosing strategy for enoxaparin in morbidly obese patients is currently unknown. Previous studies have demonstrated a negative correlation between body weight and anti-Xa activity and enoxaparin 40 mg daily resulted in subtherapeutic anti-Xa levels in 82% of patients. The objective of this study was to assess anti-Xa target attainment in patients receiving enoxaparin at a dose of 40 mg twice daily, 60 mg twice daily, or 0.5 mg/kg twice daily. Methods: This study was a single-center retrospective cohort study of critically ill patients with a BMI ≥ 40 kg/m2 receiving prophylactic enoxaparin at a dose of 40 mg twice daily, 60 mg twice daily, or 0.5 mg/kg twice daily. The primary outcome was attainment of a target anti-Xa level (0.2-0.5 IU/mL). Secondary outcomes included the incidence of VTE, major bleeding, subtherapeutic anti-Xa, and supratherapeutic anti-Xa. Results: Sixty-five patients were evaluated, and four patients were excluded. Twenty-eight patients received 40 mg twice daily, twenty-two patients received 60 mg twice daily, and eleven patients received 0.5 mg/kg twice daily. Target anti-Xa levels were achieved more often among patients receiving 0.5 mg/kg twice daily compared to both 60 mg twice daily and 40 mg twice daily (100% versus 59.1% versus 21.4%, p < 0.001). VTE was rare occurring in one patient receiving 60 mg twice daily. Major bleeding occurred in three patients, two were receiving 60 mg twice daily and one was receiving 40 mg twice daily. Conclusions: Among morbidly obese ICU patients, enoxaparin 0.5 mg/kg twice daily was associated with a significantly greater rate of anti-Xa target attainment. This indicates that an aggressive, weight-based dosing method may be optimal among morbidly obese critical care patients. Future studies are necessary to determine the impact of this dosing regimen on clinically relevant outcomes.