title: Synergistic or independent impacts of low frequency of going outside the home and social isolation on functional decline: A 4-year prospective study of urban Japanese older adults.
abstract: OBJECTIVE
  Decreased frequency of going outside the home and being socially isolated are regarded as predictors of poor health. The object of the present study was to clarify whether these factors have synergistic or independent impacts on future functional decline.
  
  
  METHODS
  We examined a prospective cohort of 2427 community-dwelling persons, aged ≥65 years, who responded to the baseline mail survey in Wako City, in 2008. Participants were asked about the frequency of going outside the home, social isolation status (having contact less than once a week with anyone outside household), functional capacity (Tokyo Metropolitan Institute of Gerontology-Index of Competence), age, sex, annual income, self-rated health, depressive mood and mobility.
  
  
  RESULTS
  Of 1575 persons (72.1%) who completely responded to the follow-up survey (T2) in 2012, we defined the groups as follows: group 1, not isolated and going outside the home every day (n = 897); group 2, not isolated and going outside the home less than every day (n = 311); group 3, isolated and going outside the home every day (n = 224); and group 4, isolated and going outside the home less than every day (n = 143). Multiple logistic regression analyses showed that the variables identifying group 3 for men and group 2 for women with reference to group 1 were predictors of subsequent functional decline even after adjustment for confounders (odds ratios 2.01, 1.63; 95% CI 1.20-3.38, 1.03-2.56, respectively).
  
  
  CONCLUSIONS
  Social isolation regardless of going outside the home every day for men and going outside the home less than every day regardless of being not socially isolated for women might predict functional decline. Geriatr Gerontol Int 2017; 17: 500-508.
authors.affiliation: Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Fujiwara
authors.affiliation: Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan.
authors.forename: Mariko
authors.initials: M
authors.lastname: Nishi
authors.affiliation: Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan.
authors.forename: Taro
authors.initials: T
authors.lastname: Fukaya
authors.affiliation: Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan.|Sei-Gakuin University, Saitama, Japan.
authors.forename: Masami
authors.initials: M
authors.lastname: Hasebe
authors.affiliation: Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan.
authors.forename: Kumiko
authors.initials: K
authors.lastname: Nonaka
authors.affiliation: Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Koike
authors.affiliation: Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Suzuki
authors.affiliation: Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan.
authors.forename: Yoh
authors.initials: Y
authors.lastname: Murayama
authors.affiliation: Nihon Fukushi University, Aichi, Japan.
authors.forename: Masashige
authors.initials: M
authors.lastname: Saito
authors.affiliation: Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan.
authors.forename: Erika
authors.initials: E
authors.lastname: Kobayashi
mesh_terms: D000203:Activities of Daily Living; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D015577:Geriatric Assessment / Q000379:methods; D006801:Humans; D057187:Independent Living / Q000523:psychology*; D007398:Interpersonal Relations; D007564:Japan; D016015:Logistic Models; D008137:Longitudinal Studies; D008297:Male; D015999:Multivariate Analysis; D011237:Predictive Value of Tests; D011446:Prospective Studies; D018570:Risk Assessment; D012737:Sex Factors; D012934:Social Isolation / Q000523:psychology*; D011795:Surveys and Questionnaires; D014041:Tokyo; D014505:Urban Population; D016138:Walking / Q000706:statistics & numerical data*
keywords: functional decline; going outside the home; social isolation; urban Japanese elderly