(ASPOT17) Trends in concomitant prescribing of anticoagulants and antiseizure medications among people with stroke in the United Kingdom.

Background:
Post-stroke seizure is an important complication which may require long-term treatment with antiseizure medications (ASMs). Current clinical guidelines do not recommend the use of antiseizure medications in combination with oral anticoagulants. However, there are lack of population-base studies monitoring the utilisation of this medication combination.

Objectives:
This study aimed to identify temporal trends in the combined use of oral anticoagulants and ASMs in people with stroke.

Methods:
A retrospective cohort study was conducted using the UK Clinical Practice Research Datalink (CPRD) data. People aged ≥18 years who have been diagnosed with stroke between January 1, 2011 and December 31, 2020 were identified. First stroke-related general practitioner visit was considered as the ‘index stroke diagnosis’. People with at least one oral anticoagulant prescription within one year following stroke were included. Concomitant use of oral anticoagulants and ASMs was defined as having overlapping prescriptions for at least 14 days. Incidence rates of concomitant medication use were calculated for different combinations of interest. Poisson regression models were used to examine the temporal trends.

Results:
Of 17,796 people using anticoagulants, 2,850 had a concomitant ASM prescription for at least 14 days. Compared to 2012, the overall incidence rates of concomitant use of oral anticoagulants and ASMs increased significantly in 2017 (from 15.3 to 19.6 per 100 anticoagulant users; p=0.0022) and in 2018 (to 18.8 per 100 anticoagulant users; p=0.0129). Between 2012 and 2020, the incidence rates of concomitant use of non-Vitamin K oral anticoagulants (NOACs) and ASMs increased significantly from 1.4 to 13.4 per 100 anticoagulant users (p < 0.0001), while the concomitant use of Vitamin K antagonists (VKAs) with ASMs decreased from 14.3 to 3.0 per 100 anticoagulant users (p < 0.0001) during the same period. By ASM regimen, the incidence rates of concomitant use of oral anticoagulants and non-enzyme inducing ASMs increased significantly in 2017 (from 13.9 to 18.3 per 100 anticoagulant users; p=0.0010) and in 2018 (to 17.7 per 100 anticoagulant users; p=0.0039) compared to 2012. In contrast, no significant changes were observed over time for the concomitant use of oral anticoagulants and enzyme-inducing ASMs (from 2.3 to 1.5 per 100 anticoagulant users; p=0.1294).

Conclusions:
An increasing trend was observed in the combined use of anticoagulants and ASMs. Notably, NOACs were preferred over VKAs, and the use of non-enzyme-inducing ASMs increased in recent years. The findings of this study will contribute to a better understanding of the current treatment patterns in managing post-stroke seizures. Further research is needed to investigate the potential drug-drug interactions between oral anticoagulants and ASMs.