Objective: To recommend strategies to bridge therapy with low-molecular-weight heparin (LMWH) in obese patients and in patients with renal dysfunction.
Methods: A MEDLINE search was performed of the literature from January 1966-November 2005. Published material dealing with bridging of anticoagulation therapy or short-term use of LMWH therapy in patients with renal dysfunction or obesity was reviewed. The manufacturers of enoxaparin, dalteparin, and tinzaparin were contacted for the references used to determine dosing recommendations.
Results: Although LMWH has been commonly used to bridge therapy, our search revealed no trials that specifically examined LMWH bridge therapy in obese patients or in patients with renal dysfunction. However, nine trials using LMWH in obese patients and 14 trials using LMWH in patients with renal dysfunction were identified. When compared with normal-weight individuals, obese patients receiving enoxaparin and dalteparin based on total body weight did not demonstrate higher hemorrhage rates or antifactor Xa levels. Subtherapeutic antifactor Xa levels were more common with once-daily dosing of enoxaparin than with dosing every 12 hours. Enoxaparin accumulates in patients with a creatinine clearance of 30 ml/minute or less; in this population, enoxaparin dosage adjustments have been attempted. Tinzaparin does not accumulate in patients with a creatinine clearance of 20 ml/minute or greater after at least 10 days of dosing.
Conclusion: Obese patients, weighing 90-150 kg, receiving LMWH for bridge therapy should receive dosages based on total body weight. Unfractionated heparin is recommended in patients weighing more than 150 kg; however, if LMWH is used, antifactor Xa levels should be monitored. Bridging with enoxaparin should be limited to patients with a creatinine clearance greater than 30 ml/minute. The use of enoxaparin 1 mg/kg once/day for patients with a creatinine clearance of 30 ml/minute or less is not recommended for anticoagulation bridge therapy. Tinzaparin may be considered for cross-coverage of high-risk patients with recent or recurrent venous thromboembolism who have a creatinine clearance of at least 20 ml/minute.