Prevalence of oral anticoagulant use among people with and without Alzheimer’s disease

BACKGROUND: Although cardio- and cerebrovascular diseases are common among people with Alzheimer's disease (AD), it is unknown how the prevalence of oral anticoagulant (OAC) use changes in relation to AD diagnosis. We investigated the prevalence of OAC use in relation to AD diagnosis in comparison to a matched cohort without AD. METHODS: Register-based Medication use and Alzheimer's disease (MEDALZ) cohort includes 70 718 Finnish people with AD diagnosed between 2005-2011. Point prevalence of OAC use (prescription register) was calculated every three months with three-month evaluation periods, from five years before to five years after clinically verified diagnosis and compared to matched cohort without AD. Longitudinal association between AD and OAC use was evaluated by generalized estimating equations (GEE). RESULTS: OAC use was more common among people with AD until AD diagnosis, (OR 1.17; 95% CI 1.13-1.22), and less common after AD diagnosis (OR 0.87; 95% CI 0.85-0.89), compared to people without AD. At the time of AD diagnosis, prevalence was 23% and 20% among people with and without AD, respectively. OAC use among people with AD began to decline gradually two years after AD diagnosis while continuous increase was observed in the comparison cohort. Warfarin was the most common OAC, and atrial fibrillation was the most common comorbidity in OAC users. CONCLUSION: Decline in OAC use among people with AD after diagnosis may be attributed to high risk of falling and problems in monitoring. However, direct oral anticoagulants (DOACs) that are nowadays more commonly used require less monitoring and may also be safer for vulnerable people with AD.