Changes in quality of vitamin K antagonist treatment and clinical outcomes during Ramadan: a Dutch population-based...

Ramadan fasting alters the timing and content of food, including dietary vitamin K, and medication intake, potentially affecting stability of vitamin K antagonist (VKA) treatment and clinical outcomes.

To assess population-level changes in VKA treatment quality and incidence of clinical events, including bleeding and venous and arterial thromboembolism, during Ramadan in the Netherlands.

Data from 17 Dutch anticoagulation clinics were linked to Statistics Netherlands. Prevalent VKA users in 2013-2019 with an immigration background who were likely to fast during Ramadan (ie, the Ramadan cohort) were studied from 2 months preceding Ramadan until 2 months after. During each 30-day interval, VKA treatment quality and risk of clinical events were assessed. A cohort of native Dutch VKA users was studied as negative control.

The Ramadan cohort included 3835 VKA users (median age 65.8 years, 55.2% male). Frequency of international normalized ratio (INR) monitoring, INR variability, and time within target range remained similar across Ramadan. However, the proportion of supratherapeutic INRs was slightly higher during (18.9% ± 31.5% [mean ± SD]) and after Ramadan (month +1, 19.9% ± 32.7% and month +2, 19.7% ± 32.8%) compared with before (month -2, 18.1 ± 30.9% and month -1, 17.8 ± 31.5%). Meanwhile, there was a higher proportion of clinically relevant dose reductions during Ramadan (4.7%) than the other months (3.6%-4.3%). These were not observed in the native Dutch cohort (N = 139,207). Monthly risk of the composite of bleeding and thromboembolic events remained unchanged across Ramadan in both cohorts.

There were no clinically relevant population-level changes across Ramadan in VKA treatment quality and clinical outcomes, except for a slightly higher proportion of supratherapeutic INRs and dose reductions.