Stroke risk reduction with oral anticoagulation using CHA2DS2-VASc in a Japanese AF population: A modeling analysis

Background: Current clinical guidelines recommend that risk stratification for ischaemic stroke in patients with nonvalvular AF (NVAF) should be performed using the CHA2DS2-VASc score (Congestive heart failure, Hypertension, Age≥ 75years [double], Diabetes mellitus, previous thromboembolism [double], Vascular disease, Age 65-74years, and female gender) to aid decision making for antithrombotic treatment, with a preference for Non-Vitamin K Oral Anticoagulants (NOACs) in those with CHA2DS2-VASc score ≥1. However, CHA2DS2-VASc score is not recommended in the 2014 Japanese Circulation Society (JCS) guidelines for patients with NVAF.

Methods: To assess the impact of the JCS approach to stroke prevention in AF, and model the impact of using a CHA2DS2-VASc based 2-step decision making strategy, we calculated the incidence of ischaemic stroke in NVAF patients without OAC on basis of the CHADS2 and CHA2DS2-VASc scores using published Japanese data, and estimated the preventable number of stroke events.

Results: Using a CHA2DS2-VASc-based approach, the potential annual stroke events based on the estimated total number of NVAF patients in Japan was 889,000, as follows: 4369 for dabigatran 150 mg, 6049 for dabigatran 110mg, 5918 for rivaroxaban (intention-to-treat; ITT), 5302 for apixaban, 5843 for edoxaban 60mg (ITT), and 7598 for edoxaban 30 mg (ITT), respectively. Using a CHADS2 score-based approach, the number of potential stroke events was much greater for each agent.

Conclusion: Our modelling analysis has shown that when considering antithrombotic treatment for Japanese NVAF patients, using a CHA2DS2-VASc-based approach would allow greater opportunities for stroke prevention.