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The effects of fasting in muslim patients taking warfarin.
J Thromb Haemost. 2013 Dec 20;
Authors: Lai Y, Cheen M, Lim S, Yeo F, Nah S, Kong M, Mya D, Lee L, Ng H
Abstract
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 time within therapeutic range (%TTR) before, during and after the Muslim fasting month (Ramadan) in stable warfarinised Muslim patients.
PATIENTS/METHODS: In this prospective study, weekly INR readings were taken at home visits on participating patients during three study periods- before, during and after Ramadan. Readings were blinded to patients and their primary physicians except when pre-set study end-points 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<0.001) after Ramadan. There was no significant difference (p=1.000) in mean INR between the non-Ramadan months.%TTR declined from 80.99% before Ramadan to 69.56% during Ramadan (p=0.453). The first out-of-range INR was seen around 12.1 days (95% CI 9.0-15.1) after the start of fasting and returned within range about 10.8 days (95% CI 7.9-13.7) after Ramadan. Time above range increased from 10.80% pre-Ramadan to 29.87% during Ramadan (p=0.027), while time below range increased from 0.57% during Ramadan to 15.49% post-Ramadan (p=0.006). No bleeding or thrombotic events were recorded.
CONCLUSIONS: Fasting significantly increases the mean INR of medically stable patients taking warfarin and the likelihood of having an INR above therapeutic targets. For patients maintained at the higher end of INR target ranges or at increased risk of bleeding, closer monitoring or dosage adjustment may be necessary during fasting. This article is protected by copyright. All rights reserved.
PMID: 24354801 [PubMed - as supplied by publisher]