title: Risk of stroke and heart failure attributable to atrial fibrillation in middle-aged and elderly people: Results from a five-year prospective cohort study of Japanese community dwellers.
abstract: BACKGROUND
  The relative and absolute risks of stroke and heart failure attributable to atrial fibrillation (AF) have not been sufficiently examined.
  
  
  METHODS
  A prospective study of 23,731 community-dwelling Japanese individuals was conducted. Participants were divided into two groups based on the presence or absence of prevalent AF (n = 338 and n = 23,393, respectively). Excess events (EE) due to AF and relative risks (RRs) determined using the non-AF group as the reference for incident stroke and heart failure were estimated using Poisson regression stratified by age groups (middle-aged: 40-69 years old; elderly: 70 years of age or older) after adjustment for sex and age.
  
  
  RESULTS
  There were 611 cases of stroke and 98 cases of heart failure during the observation period (131,088 person-years). AF contributed to a higher risk of stroke both in middle-aged individuals (EE 10.4 per 1000 person-years; RR 4.88; 95% confidence interval [CI], 2.88-8.29) and elderly individuals (EE 18.3 per 1000 person-years; RR 3.05; 95% CI, 2.05-4.54). AF also contributed to a higher risk of heart failure in middle-aged individuals (EE 3.7 per 1000 person-years; RR 8.18; 95% CI, 2.41-27.8) and elderly individuals (EE 15.4 per 1000 person-years; RR 7.82; 95% CI, 4.11-14.9). Results obtained from multivariate-adjusted analysis were similar (stroke: EE 8.9 per 1000 person-years; RR 4.40; 95% CI, 2.57-7.55 in middle-aged and EE 17.4 per 1000 person-years; RR 2.97; 95% CI, 1.99-4.43 in elderly individuals; heart failure: EE 3.1 per 1000 person-years; RR 7.22; 95% CI, 2.06-25.3 in middle-aged and EE 14.1 per 1000 person-years; RR 7.41; 95% CI, 3.86-14.2 in elderly individuals).
  
  
  CONCLUSIONS
  AF increased the risk of stroke by the same magnitude as that reported previously in Western countries. AF increased the RR of heart failure more than that in Western populations.
authors.affiliation: Department of Internal Medicine, Iwate Medical University, Morioka, Japan; Department of Internal Medicine, Morioka Tsunagi Onsen Hospital, Morioka, Japan. Electronic address: m-ohsawa@k2.dion.ne.jp.
authors.forename: Masaki
authors.initials: M
authors.lastname: Ohsawa
authors.affiliation: Department of Preventive Medicine and Public Health, Keio University, Tokyo, Japan.
authors.forename: Tomonori
authors.initials: T
authors.lastname: Okamura
authors.affiliation: Department of Hygiene and Preventive Medicine, Iwate Medical University, Yahaba-cho, Iwate, Japan.
authors.forename: Kozo
authors.initials: K
authors.lastname: Tanno
authors.affiliation: Department of Neurosurgery, Iwate Medical University, Morioka, Japan.
authors.forename: Kuniaki
authors.initials: K
authors.lastname: Ogasawara
authors.affiliation: Department of Nutritional Sciences, Morioka University, Takizawa, Iwate, Japan.
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Itai
authors.affiliation: Department of Hygiene and Preventive Medicine, Iwate Medical University, Yahaba-cho, Iwate, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Yonekura
authors.affiliation: Department of Internal Medicine, Morioka Tsunagi Onsen Hospital, Morioka, Japan.
authors.forename: Kazuki
authors.initials: K
authors.lastname: Konishi
authors.affiliation: Department of Neurosurgery, Iwate Medical University, Morioka, Japan.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Omama
authors.affiliation: Department of Clinical Nursing, Shiga University of Medical Science, Otsu, Japan.
authors.forename: Naomi
authors.initials: N
authors.lastname: Miyamatsu
authors.affiliation: Department of Community Health Sciences, University of Calgary, Calgary, Canada.
authors.forename: Tanvir Chowdhury
authors.initials: TC
authors.lastname: Turin
authors.affiliation: Department of Internal Medicine, Iwate Medical University, Morioka, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Morino
authors.affiliation: Department of Internal Medicine, Iwate Medical University, Morioka, Japan.
authors.forename: Tomonori
authors.initials: T
authors.lastname: Itoh
authors.affiliation: Department of Hygiene and Preventive Medicine, Iwate Medical University, Yahaba-cho, Iwate, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Onoda
authors.affiliation: Department of Hygiene and Preventive Medicine, Iwate Medical University, Yahaba-cho, Iwate, Japan.
authors.forename: Kiyomi
authors.initials: K
authors.lastname: Sakata
authors.affiliation: Department of Internal Medicine, Iwate Medical University, Morioka, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Ishibashi
authors.affiliation: Department of Internal Medicine, Iwate Medical University, Morioka, Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Makita
authors.affiliation: Department of Internal Medicine, Iwate Medical University, Morioka, Japan.
authors.forename: Motoyuki
authors.initials: M
authors.lastname: Nakamura
authors.affiliation: Department of Internal Medicine, Iwate Medical University, Morioka, Japan.
authors.forename: Fumitaka
authors.initials: F
authors.lastname: Tanaka
authors.affiliation: Department of Health and Physical Education, Faculty of Education, Iwate University, Morioka, Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Kuribayashi
authors.affiliation: Iwate Health Service Association, Morioka, Japan.
authors.forename: Mutsuko
authors.initials: M
authors.lastname: Ohta
authors.affiliation: The Research Institute of Strategy for Prevention, Tokyo, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Okayama
mesh_terms: D000328:Adult; D000368:Aged; D001281:Atrial Fibrillation / Q000150:complications*; D005260:Female; D006333:Heart Failure / Q000453:epidemiology*; D006801:Humans; D057187:Independent Living; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D015995:Prevalence; D011446:Prospective Studies; D012306:Risk; D020521:Stroke / Q000453:epidemiology*
keywords: Absolute risk; Atrial fibrillation; Heart failure; Prospective study; Relative risk; Stroke