The duration of anticoagulation bridging therapy in clinical practice may significantly exceed that observed in clinical trials

Background Clinical trials involving frequent, standardized monitoring of the international normalized ratio (INR) demonstrated that a short course of low-molecular-weight-heparin (LMWH) can successfully bridge patients to oral anticoagulation. However, rigidly performed INR testing is often not feasible in the outpatient setting in actual clinical practice. The purpose of this study was to determine if the anticoagulation results of clinical trials of LMWH bridging therapy are also achieved in a single-center clinical practice setting. Methods We conducted a retrospective analysis of 100 patients initiating warfarin while receiving LMWH under the care of a university-based anticoagulation management service. Results Mean patient age was 56.1 +/- 16.3 years. The commonest indications for anticoagulation were venous thrombosis (57%) and atrial fibrillation (25%). Mean initial warfarin dose was 5.1 +/- 1.8 mg/day; 30% of patients received antiplatelet therapy. The mean total duration of LMWH therapy was 12.0 +/- 8.2 days, of which 9.8 +/- 8.0 days (median 7.5 days; interquartile range 4.3-13.0 days) occurred in the outpatient setting. Forty-one percent of patients received outpatient LMWH for < 7 days, 40% for 7-14 days, and 19% for > 14 days. A mean of 3.9 +/- 2.0 INRs were performed during LMWH therapy. Complications included It minor and 1 major bleeding episodes and 1 thrombotic event. Conclusions The duration of LMWH bridging therapy in practice may be significantly greater than previously reported in clinical trials, and the incidence of patients requiring prolonged (> 14 days) LMWH therapy is relatively high. Outpatient LMWH as employed in clinical practice safely bridges patients to oral anticoagulation. Strategies to shorten the duration of LMWH therapy are needed and are likely to improve clinical outcomes and reduce health care expenses.