Background Data on stroke, mortality and associated comorbidities in elderly patients with atrial fibrillation (AF) in Japan may differ from Western countries. There have been few systematic comparisons between stroke risk profiles and outcomes among community-based elderly (aged ≥75 years) patients with AF in Japan and the UK.

Objective and methods We compared clinical characteristics, stroke risk and outcomes among elderly patients with AF from the Fushimi AF Registry (Japan; N=1791) and the Darlington AF Registry (UK; N=1338).

Results The Fushimi cohort had a mean age 81.8 (standard deviation (SD) 5.3) years and CHA₂DS₂-VASc (congestive heart failure, hypertension, age ≥75 years (double), diabetes mellitus, previous thromboembolism (double), vascular disease, age 65–74 years and female gender) score 4.3 (1.4), whereas the Darlington cohort had a mean age 83.6 (5.7) years and CHA₂DS₂-VASc score 4.4 (1.4). Over a 12-month follow-up period, observed stroke and mortality rates in Fushimi were 3.4% (n=61) and 11.5% (n=206), while corresponding event rates in the Darlington cohort were 4.4% (n=59) and 14.1% (n=188), respectively. Appropriate use of oral anticoagulation (OAC, essentially a vitamin K antagonist) was <60% in both registries.

On multivariable analysis, ethnicity (Japan vs UK) was neither associated with the risk of stroke (OR 0.92, 95% CI 0.63 to 1.36; p=0.69) nor death (OR 0.92, 95% CI 0.80 to 1.27; p=0.92). In a subgroup analysis of elderly patients not receiving OAC (n=1489), a history of stroke was associated with the risk of stroke (OR 2.42, 95% CI 1.39 to 4.12; p=0.002), but not ethnicity (OR 0.86, 95% CI 0.50 to 1.47; p=0.58).

Conclusions Elderly (age ≥75 years) patients with AF in both Japan and the UK are at similarly high risk of stroke and death, with OAC still underused in both populations. Ethnicity was not independently associated with the risk of stroke, regardless of OAC use or non-use.