Premium
The effects of fasting in Muslim patients taking warfarin
Author(s) -
Lai Y. F.,
Cheen M. H. H.,
Lim S. H.,
Yeo F. H. I.,
Nah S. C.,
Kong M. C.,
Mya D.,
Lee L. H.,
Ng H. J.
Publication year - 2014
Publication title -
journal of thrombosis and haemostasis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.947
H-Index - 178
eISSN - 1538-7836
pISSN - 1538-7933
DOI - 10.1111/jth.12496
Subject(s) - medicine , warfarin , target range , prospective cohort study , major bleeding , significant difference , pediatrics , atrial fibrillation , economics , macroeconomics
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 M uslim fasting month ( R amadan) in stable warfarinised M uslim 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‐ R amadan 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‐ R amadan months. % TTR declined from 80.99% before R amadan to 69.56% during R amadan ( 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 to range at about 10.8 days (95% CI , 7.9–13.7) after R amadan. Time above range increased from 10.80% pre‐ R amadan to 29.87% during R amadan ( P = 0.027), while time below range increased from 0.57% during R amadan to 15.49% post‐ R amadan ( 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.