In five patients, INR was measured twice daily for 5 days. By simulating preoperative discontinuation of warfarin therapy, we found that the INR decreases exponentially, with wide interpatient variation in the rate of decrease.
Age is associated with a slower rate of decrease.
For patients with a higher steady-state INR, a longer wait is necessary. Ann Intern Med. From the University of California, Davis, California. For current author addresses, see end of text . Long-term warfarin therapy must frequently be discontinued before surgical and dental procedures.