title: Non-therapeutic anti-FXa levels are common among medical ward patients treated with enoxaparin.
abstract: Thromboembolism is treated with a weight-adjusted enoxaparin dose without the need for laboratory monitoring. This study aims to determine the prevalence of sub and supra-therapeutic anti-factor Xa (aFXa) levels among medical ward patients treated with enoxaparin, and to identify potential factors associated with non-therapeutic aFXa levels. aFXa levels were measured in a cohort of medical ward patients treated with curative enoxaparin regimen (1 mg/kg bid) in the Ha'emek Medical Center in the northeastern area of Israel. The relative risk (RR) ratio for sub and supra-therapeutic aFXa levels was estimated in demographic and clinical subgroups. Of the 294 included patients, only 78.6% had therapeutic aFXa levels, while 13.3% and 8.1% had sub and supra-therapeutic levels, respectively. On univariate analysis, females, smoking, BMI ≥ 30, and cancer were significantly associated with supra-therapeutic aFXa levels; fibrates and warfarin use were significantly associated with sub-therapeutic aFXa levels (P < 0.05). On multivariate analysis, females and patients with cancer were independently at increased risk for supra-therapeutic levels RR 3.35(95% CI 1.50, 7.48), RR 3.61(95% CI 1.50, 8.70), respectively. Fibrates and warfarin were associated with sub-therapeutic levels RR 2.99(95% CI 1.44, 6.20), RR 3.42(95% CI 1.73, 6.76), respectively. Standard curative enoxaparin regimen is associated with increased risk for supra-therapeutic aFXa levels in females and patients with cancer and sub-therapeutic levels in patients treated with fibrates and warfarin. This may suggest the need for anticoagulation monitoring in high-risk patients with these conditions.
authors.affiliation: Medicine Department C, Ha'emek Medical Center, Afula, Israel. saliba_wa@clalit.org.il
authors.forename: Walid
authors.initials: W
authors.lastname: Saliba
authors.forename: Orna
authors.initials: O
authors.lastname: Nitzan
authors.forename: Wasseem
authors.initials: W
authors.lastname: Rock
authors.forename: Gilat
authors.initials: G
authors.lastname: Ron
authors.forename: Luci
authors.initials: L
authors.lastname: Zalman
authors.forename: Lee
authors.initials: L
authors.lastname: Goldstein
authors.forename: Idit
authors.initials: I
authors.lastname: Lavi
authors.forename: Mazen
authors.initials: M
authors.lastname: Elias
mesh_terms: D000368:Aged; D000925:Anticoagulants / Q000627:therapeutic use; D001323:Autoantibodies / Q000097:blood*; D017984:Enoxaparin / Q000627:therapeutic use*; D015951:Factor Xa / Q000276:immunology*; D005260:Female; D005343:Fibrinolytic Agents / Q000627:therapeutic use*; D006801:Humans; D007557:Israel; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D013923:Thromboembolism / Q000188:drug therapy*
chemical_list: D000925:Anticoagulants; D001323:Autoantibodies; D017984:Enoxaparin; D005343:Fibrinolytic Agents; D015951:Factor Xa