Background and rationale for the study (Risks of an excessively prolonged INR) The risk of hemorrhage in patients with asymptomatic warfarin-associated coagulopathy has been highlighted by Hylek and colleagues (8). In this study, 114 patients who presented with INR values of more than 6.0 simply had their warfarin withheld until the INR had declined to the desired range. In the two-week follow-up period, 10 of the 114 (8.8%, 95% confidence interval (CI) 3.6 to 14.0) patients experienced bleeding including 5 major and two fatal bleeds. Thus the risk of major hemorrhage and fatal hemorrhage was 4.4% (95% CI 0.6, 8.1), and 1.7% (95% CI 0, 4.2), respectively. Similarly, Oden and colleagues (4) demonstrated the mortality rate attributable to bleeding per 100 patient years of follow-up was 22 fold higher in patients with INR values between 6.0 and 6.9, compared with patients with an INR between 2.0 and 2.4. The observation that excessive elevation of the INR is associated with bleeding suggests that identifying an effective technique to lower the INR will reduce bleeding.