Clinical Feasibility of Monitoring Enoxaparin Anti-Xa Concentrations: Are We Getting it Right?

Abstract

<b>Background:</b> Anti-Xa monitoring is utilized to measure the extent of anticoagulation in certain patient populations receiving enoxaparin. It is essential to accurately obtain this pharmacodynamic marker for safe and effective anticoagulation management. <b>Objectives:</b> To determine the frequency of correctly drawn anti-Xa concentrations in accordance with predefined institutional criteria and to determine the number of dose adjustments implemented based on incorrectly drawn anti-Xa concentrations. <b>Methods:</b> This was a retrospective, single-center, cohort study among adult patients who received treatment doses of enoxaparin with measured anti-Xa concentrations. Patients were excluded if they were pregnant, on hemodialysis, or received prophylactic dosing. Anti-Xa levels were defined as correctly measured if they were drawn 3 to 5 hours after the dose during steady state concentrations. Descriptive statistics were performed and analyzed via SPSS software. <b>Results:</b> Overall, 203 patients were reviewed and 59 patients with 74 anti-Xa levels were included. The majority of anti-Xa levels (57/74; 77%) were drawn incorrectly and often resulted in collection of repeat anti-Xa samples. There were 12 documented dose adjustments and approximately 42% (5/12) were based on incorrectly drawn anti-Xa levels. Anti-Xa levels were within target range approximately 45% of the time. <b>Conclusions:</b> Enoxaparin anti-Xa concentrations are frequently drawn incorrectly and dose adjustments are often performed based on these unsupported anti-Xa levels. This may present a potential risk to compromise patient safety.