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.
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Contributors MA and GYHL are joint senior authors. GYHL formulated the hypothesis, supervised the analysis and manuscript drafting. KS performed the analysis and wrote the first draft. All other authors contributed to data collection and critical review of the manuscript.
Funding The Fushimi AF Registry is supported by research funding from Boehringer Ingelheim, Bayer Healthcare, Pfizer, Bristol-Myers Squibb, Astellas Pharma, AstraZeneca, Daiichi-Sankyo, Novartis Pharma, MSD, Sanofi-Aventis and Takeda Pharmaceutical. This research was partially supported by the Practical Research Project for Life-Style related Diseases including Cardiovascular Diseases and Diabetes Mellitus from Japan Agency for Medical Research and Development, AMED (15656344).
Competing interests KS: received a research grant from the Sasakawa foundation. DAL: investigator-initiated educational grants from Bayer Healthcare, Boehringer Ingelheim and Bristol-Myers-Squibb. Speaker's bureau for Boehringer Ingelheim, Bayer, and Bristol Myers Squibb/Pfizer. DAL is a Steering Committee member of a Bristol-Myers-Squibb Phase IV trial. AW: clinical advisor to Boehringer Ingelheim, Pfizer, BMS, Sanofi Aventis and Daiichi-Sankyo. Speaker for Boehringer Ingelheim, Sanofi and Pfizer. MA: received lecture fees from Pfizer, Bristol-Myers Squibb, Boehringer Ingelheim, Bayer Healthcare. GYHL: consultant for Bayer/Janssen, Astellas, Merck, Sanofi, BMS/Pfizer, Biotronik, Medtronic, Portola, Boehringer Ingelheim, Microlife and Daiichi-Sankyo. Speaker for Bayer, BMS/Pfizer, Medtronic, Boehringer Ingelheim, Microlife, Roche and Daiichi-Sankyo.
Ethics approval Ethical committees of the National Hospital Organization Kyoto Medical Center and Ijinkai Takeda General Hospital.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement Data sharing would need application from respective IRBs and data management authorities in Japan and the UK.