title: Comparison of anti-Xa levels in obese and non-obese pediatric patients receiving treatment doses of enoxaparin.
abstract: OBJECTIVE
  To determine if using actual body weight to dose enoxaparin in obese pediatric patients results in higher anti-Xa levels compared with non-obese pediatric patients.
  
  
  METHODS
  This was a retrospective case-matched study of obese and non-obese pediatric patients receiving treatment doses of enoxaparin in a tertiary care children's hospital. Patients were included if they were initiated on treatment doses of enoxaparin, had appropriate anti-Xa levels drawn, and were between 2 and 18 years of age. Patients with renal insufficiency, hyperbilirubinemia, goal anti-Xa level <0.5 or >1 unit/mL, or receiving mechanical circulatory support were excluded. Obese patients who met study criteria were matched on a 1:1 basis with non-obese patients.
  
  
  RESULTS
  All baseline characteristics were similar except for body mass index percentile (98.2 ± 2 vs 48.7 ± 15, P < .01). Obese patients had higher initial anti-Xa levels (0.67 ± 0.27 vs 0.53 ± 0.24 unit/mL, P = .028). Over time, obese patients required a lower mean dose to achieve therapeutic anti-Xa levels than non-obese patients (0.81 ± 0.19 vs 1.1 ± 0.4 mg/kg, P = .005).
  
  
  CONCLUSIONS
  The mean initial anti-Xa level was higher in obese pediatric patients compared with non-obese pediatric patients, but a dosage adjustment was not required. Obese patients may need closer monitoring over time to avoid supratherapeutic levels and possible bleeding events.
authors.affiliation: Department of Pharmacy, Texas Children's Hospital, Houston, TX 77030, USA.
authors.forename: Ashley A
authors.initials: AA
authors.lastname: Richard
authors.forename: Shelly
authors.initials: S
authors.lastname: Kim
authors.forename: Brady S
authors.initials: BS
authors.lastname: Moffett
authors.forename: Lisa
authors.initials: L
authors.lastname: Bomgaars
authors.forename: Donald
authors.initials: D
authors.lastname: Mahoney
authors.forename: Donald L
authors.initials: DL
authors.lastname: Yee
mesh_terms: D000293:Adolescent; D000925:Anticoagulants / Q000008:administration & dosage*; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D016903:Drug Monitoring; D017984:Enoxaparin / Q000008:administration & dosage*; D015951:Factor Xa / Q000032:analysis*; D065427:Factor Xa Inhibitors; D005260:Female; D006801:Humans; D008297:Male; D009765:Obesity / Q000097:blood*; D012189:Retrospective Studies
chemical_list: D000925:Anticoagulants; D017984:Enoxaparin; D065427:Factor Xa Inhibitors; D015951:Factor Xa