Prevalence of atrial fibrillation in the general population of Japan: An analysis based on periodic health examination
Introduction
Atrial fibrillation (AF) is one of the common arrhythmias encountered in general practice as well as in the field of cardiology. AF could be responsible for increased mortality and various morbidities including clinical symptoms, impaired cardiac function and thromboembolism [1], [2], [3], [4], [5]. Several epidemiological studies from Western countries showed that prevalence of AF increased with the aging of the population and that the increase became striking after 60 years of age, affecting approximately 8% to 9% of people aged 80 years or more [6], [7], [8], [9], [10].
Several predisposing factors for AF other than aging are known [11], [12]. Among them are hypertension, myocardial infarction, valvular heart disease, congestive heart failure, diabetes mellitus, alcohol drinking and others [11], [12]. The prevalence, mortality and morbidity of various cardiovascular diseases may differ between Western countries and Japan. For example, prevalence of hypertension of Japan seems higher than that of the USA, but lower than that of England and Germany [13], [14], [15], [16]. Another example is coronary artery disease. The incidence of myocardial infarction is lower and the prognosis after myocardial infarction is better in Japan than in Western countries [17], [18], [19]. Therefore, it seems conceivable that the epidemiology of AF could differ between Western countries and Japan. However, the epidemiological study of AF has been limited in Japan [20], [21], [22]; these epidemiological studies [20], [21], [22] showed the prevalence of AF was lower in Japan than in Western countries [6], [7], [8], [9], [10].
Japan has a periodic health examination system for company employees and community residents that cover the country. The Industrial Safety and Health Law decrees provision of a health examination that includes an electrocardiogram for examinees aged 40 years or more. In order to determine the prevalence of AF in the general population of Japan, we conducted a cooperative epidemiological study using the data from periodic health examinations of more than 600,000 subjects over the age of 40 years.
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Subjects and methods
Data from periodic health examinations of community residents and employees of companies and local governments performed in 2003 were collected. After obtaining approval of the study design from the ethics committee of the participating institutes, which are distributed from the northern part of the main island of Honshu to Kyushu island of Japan, the health examination data were collected from company clinics, health screening centers, and local governments of the prefectures where the
Results
Data of 630,138 subjects aged 40 years or more were collected from 25 company clinics, nine health screening centers of communities, and five local governments. Approximately 47% of the subjects were male; 31% of the subjects were aged 50–59 years, 27% were aged 40–49 years, and 23% were aged 60–69 years. Employees of companies and local governments accounted for 34% of all subjects of the study group.
Major findings
The major findings of the present study were as follows. First, the prevalence rate of AF increased as people aged, and was three times greater in men than in women. Second, the estimated number of people with AF was approximately 720,000 in Japan, and the overall prevalence was 0.56%, which is two-thirds of that of the USA [8]. The number of people having AF in Japan is projected to be 1.034 million in the year of 2050, which is one fifth of that in the USA [9].
Comparison with data of previous studies
In Japan, epidemiological
Conclusions
Although limited for these reasons, the present study, based on the data of annual health examinations of more than 600,000 people, showed the rate of AF increased as the population aged in Japan, as in Western countries. The prevalence of AF was approximately two thirds of that in the USA [8], and the projected increase in the number of people having AF in Japan is modest when compared with that of the USA [9], [26] in the year of 2050.
Acknowledgements
This study was conducted with the support of the Japanese Society of Circulation.
The authors of this manuscript have certified that they comply with the Principles of Ethical Publishing in the International Journal of Cardiology [35].
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