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. 2017 Mar;52(3):214-220.
doi: 10.1310/hpj5203-214.

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

Wesley D Kufel, Robert W Seabury, William Darko, Luke A Probst, Christopher D Miller

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

Wesley D Kufel et al. Hosp Pharm. 2017 Mar.

Abstract

Background: 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. Objectives: 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. Methods: 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. Results: 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. Conclusions: 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.

Keywords: anti-Xa monitoring; enoxaparin; low molecular weight heparin; pharmacodynamic monitoring.

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Figures

Figure 1.
Figure 1.
Anti-Xa concentrations included in analysis.
Figure 2.
Figure 2.
Correctly drawn anti-Xa levels based on defined criteria: anti-Xa level drawn 3–5 hours post dose during steady state concentrations (after the third dose of every 12 hour dosing or after the second dose of every 24 hour dosing).
Figure 3.
Figure 3.
Dose adjustments based on anti-Xa level: anti-Xa level drawn 3–5 hours post dose during steady state concentrations (after the third dose of every 12 hour dosing or after the second dose of every 24 hour dosing).
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