Comparison of initial warfarin dosing in hospitalised patients considered sensitive to warfarin: low‐dose versus standard‐dose strategy

Abstract

Warfarin dosages are individualised based on disease state, target International Normalised Ratio (INR) and potential risk factors for bleeding. This retrospective case series study compared and evaluated the safety and time to reach target INR (therapeutic INR and INR >3) of two warfarin dose initiation strategies (2.5 vs 5–7.5 mg; Groups 1 and 2, respectively) in potentially warfarin‐sensitive patients. In addition, the incidence of bleeding within 15 days of starting warfarin therapy was determined. In in all, 137 patients were included in the study. The mean (±SD) time to reach an INR ≥2.0 was 7.4 ± 2.3 vs 5.84 ± 1.82 days in Groups 1 and 2, respectively. There was no significant difference between groups in patients attaining INR >3 (p = 0.1487). In conclusion, some patients considered sensitive to warfarin could receive a loading dose of 5–7.5 mg and attain therapeutic INR faster than patients receiving 2.5 mg without an increased risk of bleeding.