title: Bridging anticoagulation with low-molecular-weight heparin after interruption of warfarin therapy is associated with a residual anticoagulant effect prior to surgery.
abstract: Bridging anticoagulation with low-molecular-weight heparin (LMWH) is common in patients who require temporary interruption of warfarin before surgery or a procedure, but whether such patients have a residual anticoagulant effect just before a procedure is not known. Consecutive patients who received bridging anticoagulation with LMWH had anti-Xa levels measured just before a procedure. The proportion of patients with a residual anticoagulant effect, defined as an anti-Xa level > or = 0.10 IU/ml, was determined. Multivariable regression analysis identified predictors of a residual anticoagulant effect, expressed as an odds ratio (OR) and corresponding 95% confidence interval (CI). A pre-procedure residual anticoagulant effect was detected in 12 of 73 (16%) patients overall, in 11 of 37 (30%) patients who received therapeutic-dose LMWH, and in 1 of 36 patients (3%) who received low-dose LMWH. Receiving therapeutic-dose LMWH (OR = 118.8; 95% CI: 5.8, 999.9), and increasing age (OR = 4.0; 95% CI: 1.3, 12.5) were predictors of a residual pre-procedure anticoagulant effect. In patients who require bridging anticoagulation with LMWH, a residual anticoagulant effect from LMWH is detected in 1 of 6 patients, and receiving therapeutic-dose LMWH is the strongest predictor of such an effect.
authors.affiliation: Department of Medicine and St. Joseph's Heathcare, McMaster University, Hamilton, Canada. jdouket@mcmaster.ca
authors.forename: James D
authors.initials: JD
authors.lastname: Douketis
authors.forename: Karen
authors.initials: K
authors.lastname: Woods
authors.forename: Gary A
authors.initials: GA
authors.lastname: Foster
authors.forename: Mark A
authors.initials: MA
authors.lastname: Crowther
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000627:therapeutic use*; D001778:Blood Coagulation Disorders / Q000188:drug therapy*; D001835:Body Weight; D065427:Factor Xa Inhibitors; D005260:Female; D006470:Hemorrhage / Q000139:chemically induced; D006495:Heparin, Low-Molecular-Weight / Q000009:adverse effects / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011300:Preoperative Care / Q000379:methods; D012307:Risk Factors; D013514:Surgical Procedures, Operative; D013997:Time Factors; D016896:Treatment Outcome; D014859:Warfarin / Q000627:therapeutic use*
chemical_list: D000925:Anticoagulants; D065427:Factor Xa Inhibitors; D006495:Heparin, Low-Molecular-Weight; D014859:Warfarin