Antifactor Xa Levels in Critically Ill Korean Patients Receiving Enoxaparin for Thromboprophylaxis: A Prospective Observational Study

Abstract

The aim of this study was to investigate antifactor Xa (aFXa) levels after once daily dose of 40 mg of enoxaparin and to evaluate factors influencing aFXa levels among Korean intensive care unit (ICU) patients. This prospective observational study was conducted between August and December 2011 in medical ICUs at Samsung Medical Center. AFXa levels between 0.1 and 0.3 U/mL were considered to be effective for antithrombotic activity. Fifty-five patients were included. The median aFXa levels were 0.22 (IQR 0.17-0.26) at 4 hr, 0.06 (IQR 0.02-0.1) at 12 hr, and 0 U/mL (IQR 0-0.03) at 24 hr. The numbers of patients showing effective antithrombotic aFXa levels were 48 (87.3%), 18 (32.7%), and 0 (0%) at 4, 12 and 24 hr, respectively. At 12 hr, higher sequential organ failure assessment (SOFA) scores and hyperbilirubinemia were significantly associated with low aFXa levels (OR, 0.58; 95% CI, 0.36-0.93; P = 0.02 and 0.06; 0.003-0.87; 0.04, respectively). Once daily dose of 40 mg of enoxaparin is inadequate for maintaining effective antithrombotic aFXa levels, and the inadequacy is more salient for patients with high SOFA scores and hyperbilirubinemia.

Plasma anti-FXa level as a surrogate marker of the adequacy of thromboprophylaxis in critically ill patients: A systematic review

“…Trial characteristics are presented in Table 1. Most of these studies (10 observational studies and two RCTs) tested the effects of different dosages of enoxaparin [15][16][17][18][19][20][21][22][23][24][25][26], whereas four observational studies assessed dalteparin [27][28][29][30], and one each tested certoparin [31] and nadroparin [32]. No studies testing tinzaparin were identified.…”

“…The median peak anti-FXa levels in ICU patients varied widely, from b 0.1 IU/mL [31] to 0.35 IU/mL [27]. The median trough anti-FXa levels were reported in four studies, and they varied between undetectable and b0.1 IU/mL [27,31,18,20].…”

“…The quality of the studies according to the Down and Black score is shown in Table 2. The median total score (interquartile range, IQR) was 19 [15][16][17][18][19][20]…”

“…Five studies reported trough levels, which were generally low (0-0.10 IU/mL) and in one study the low trough level correlated with the incidence of DVT (37 vs. 11%, p = 0.026) [19]. Median trough levels were generally low or undetectable [18,20]. Nine studies reported adverse events, with none of these studies detecting any correlation between bleeding events and anti-FXa levels [15,[18][19][20]22,23,24,33,26].…”

Comparing effects of different routes of heparin administration on the serum biomarkers of thrombosis

“…In some recent studies, significantly lower anti-Xa levels have been detected following single daily dose of sc. injection of enoxaparin in critically ill patients with normal renal function [11][12][13][14][15][16]. Robinson et al reported that critically ill patients required higher doses of sc.…”