Trends in prescription of oral anticoagulants in elderly individuals with atrial fibrillation in UK primary care

Study type
Protocol
Date of Approval
Study reference ID
23_003487
Lay Summary

Anticoagulants are medications that are used to reduce the formation of blood clots. They are often prescribed to patients with irregular heart rhythm such as atrial fibrillation to prevent strokes (blood clots in the brain). The most commonly used oral anticoagulants are vitamin K antagonists (VKAs) and direct oral anticoagulants (DOACs). Although effective at reducing the risk of clotting, VKAs are impractical to use, and may be associated with significant bleeding complications. DOACs were introduced in the UK in 2008 as potentially interesting alternatives to VKAs. They work as well as warfarin in reducing blood clots but cause fewer bleedings and are also easier to use. Atrial fibrillation is common in elderly patients and oral anticoagulants have been shown to be very effective to prevent stroke in this population. However, they are often underprescribed to these patients. It is not clear whether the recent introduction of DOACs has led to an increase in the number of elderly patients prescribed anticoagulants. Therefore, the objective of this study will be to describe temporal trends in the prescription of oral anticoagulants to patients with atrial fibrillation aged 80 and above between 2011 and 2021 in the UK. We will also describe the characteristics of patients who are treated with these medications. These findings will inform physicians and public decision makers on the use of oral anticoagulants over time in elderly patients.

Technical Summary

Individuals with atrial fibrillation have a five-fold increased risk of ischaemic stroke compared to those without atrial fibrillation. Direct oral anticoagulants (DOACs) are recommended over vitamin K antagonists for most patients with nonvalvular atrial fibrillation (NVAF) for the prevention of stroke, including elderly patients. However, oral anticoagulants (OACs) are often under-prescribed to the elderly in clinical practice. A better understanding of the prescribing trends since the approval of DOACs for stroke prevention in NVAF in 2011 and obstacles to DOACs prescription in this population could help improve the management of these patients. Thus, we will conduct a cohort study to describe temporal trends in prescriptions of OACs in elderly patients in UK primary care between 2011 and 2021. The cohort will include all patients aged 80 years and older with NVAF registered in the CPRD during the study period. We will estimate incident rates of OAC prescriptions for each calendar year using a Poisson distribution, overall and stratified by age, sex, OAC molecule, and nation. We will also identify the predictors of OAC initiation and persistence. Finally, we will describe changes in baseline characteristics of elderly patients newly prescribed OACs over time. Given that OACs have been underprescribed in this elderly population, the results of this study will provide insight as to how OAC prescribing have evolved in UK primary care practices in the last decade.

Health Outcomes to be Measured

First prescription of DOACs (apixaban, edoxaban, dabigatran, rivaroxaban) and VKAs in elderly patients with NVAF, overall and by age, sex, particular comorbidities, UK nations and individual OAC molecules.
Baseline characteristics of patients newly prescribed OAC (age, sex, comorbidities, comedications, measures of health utilization).
Predictors of initiation and persistence of OAC treatment
Prevalence of OAC utilization overall and by age, sex, UK nations and OAC molecules.

Collaborators

Samy Suissa - Chief Investigator - Sir Mortimer B Davis Jewish General Hospital
Christel Renoux - Corresponding Applicant - McGill University
Ekaterina Pazukhina - Collaborator - McGill University
Erica Moodie - Collaborator - McGill University
Sarah Beradid - Collaborator - Sir Mortimer B Davis Jewish General Hospital