The effects of fasting in Muslim patients taking warfarin

Summary Background Anticoagulation with warfarin is influenced by dietary changes but the effect of fasting on warfarin therapy is unknown. Objectives To study changes in international normalized ratio (INR) and the percentage of time within therapeutic range (%TTR) before, during and after the Muslim fasting month (Ramadan) in stable warfarinised Muslim patients. Methods/Patients In this prospective study, weekly INR readings were taken at home visits from participating patients during three study periods: before, during and after Ramadan. Readings were blinded to patients and their primary physicians except for when pre‐set study endpoints were reached. Results Among 32 participating patients, mean INR increased by 0.23 (P = 0.006) during Ramadan from the pre‐Ramadan month and decreased by 0.28 (P