Prescribing of Direct Oral Anticoagulants and Warfarin to Older People with Atrial Fibrillation in UK General Practice: a Cohort Study

Background: Anticoagulation for stroke prevention in atrial fibrillation (AF) has, historically, been under-used in older people. The aim of this study was to investigate prescribing of oral anticoagulants (OACs) for people aged ≥ 75 years in the UK before and after direct oral anticoagulants (DOACs) became available.

Methods: A cohort of patients aged ≥ 75 years with a diagnosis of AF was derived from the Clinical Practice Research Datalink (CPRD) between January 1, 2003, and December 27, 2017. Patients were grouped as no OAC, incident OAC (OAC newly prescribed) or prevalent OAC (entered study on OAC). Incidence and point prevalence of OAC prescribing were calculated yearly. The risk of being prescribed an OAC if a co-morbidity was present was calculated; the risk difference (RD) was reported. Kaplan-Meier curves were used to explore persistence with anticoagulation. A Cox regression was used to model persistence with warfarin and DOACs over time.

Results: The cohort comprised 165,596 patients (66,859 no OAC; 47,916 incident OAC; 50,821 prevalent OAC). Incidence of OAC prescribing increased from 111 per 1000 person-years in 2003 to 587 per 1000 person-years in 2017. Older patients (≥ 90 years) were 40% less likely to receive an OAC (RD -0.40, 95% CI -0.41 to -0.39) than younger individuals (75-84 years). The likelihood of being prescribed an OAC was lower with a history of dementia (RD -0.34, 95% CI -0.35 to -0.33), falls (RD -0.17, 95% CI -0.18 to -0.16), major bleeds (RD -0.17, 95% CI -0.19 to -0.15) and fractures (RD -0.13, 95% CI -0.14 to -0.12). Persistence with warfarin was higher than DOACs in the first year (0-1 year: HR 1.25, 95% CI 1.17-1.33), but this trend reversed by the third year of therapy (HR 0.75, 95% CI 0.63-0.89).

Conclusions: OAC prescribing for older people with AF has increased; however, substantial disparities persist with age and co-morbidities. Whilst OACs should not be withheld solely due to the risk of falls, these results do not reflect this national guidance. Furthermore, the under-prescribing of OACs for patients with dementia or advancing age may be due to decisions around risk-benefit management.

Trial Registration: EUPAS29923 . First registered on: 27/06/2019.