title: Longitudinal association between time-varying social isolation and psychological distress after the Great East Japan Earthquake.
abstract: BACKGROUND
  The association between social isolation and psychological distress among disaster survivors is inconclusive. In addition, because these previous studies were cross-sectional in design, the longitudinal association between time-varying social isolation and psychological distress was not clear. The present study examined the longitudinal association between social isolation and psychological distress after the Great East Japan Earthquake.
  
  
  METHODS
  We analyzed longitudinal data for 959 adults who had responded to the self-report questionnaires about Lubben Social Network Scale-6 (LSNS-6) and K6 in both a community-based baseline survey (2011) and a follow-up survey (2014) after the disaster. Participants were categorized into four groups according to changes in the presence of social isolation (<12/30 of LSNS-6) at two time points (2011 and 2014): "remained socially isolated", "became not socially isolated", "remained not socially isolated", and "became socially isolated". We defined a K6 score of ≥ 10/24 as indicating the presence of psychological distress. We used multiple logistic regression analysis to estimate the adjusted odds ratios (ORs) and 95% confidence intervals (CIs) to indicate how the change in social isolation was related to changes in psychological distress over 3 years.
  
  
  RESULTS
  Among the participants who had not shown psychological distress at the baseline, the rates of deterioration of psychological distress were significantly lower in participants who "became not socially isolated" (multivariate OR = 0.26, 95% CI = 0.08-0.70) and "remained not socially isolated" (multivariate OR = 0.49, 95% CI = 0.27-0.91), compared with participants who "remained socially isolated". Among the participants who had psychological distress at the baseline, the rate of improvement of psychological distress was significantly higher in participants who "remained not socially isolated" (multivariate OR = 2.61, 95% CI = 1.08-6.44).
  
  
  CONCLUSIONS
  The present findings suggest that prevention of social isolation may be an effective public health strategy for preventing psychological distress after a natural disaster.
authors: Department of Rehabilitation, Faculty of Health Science, Tohoku Fukushi University, Sendai, Japan; Division of Epidemiology, Department of Health Informatics and Public Health, Tohoku University School of Public Health, Graduate School of Medicine, Sendai, Japan. Electronic address: sone-t@umin.ac.jp.
authors: Toshimasa
authors: T
authors: Sone
authors: Department of Preventive Medicine and Epidemiology, Tohoku Medical Megabank Organization, Tohoku University, Sendai, Japan.
authors: Naoki
authors: N
authors: Nakaya
authors: Division of Epidemiology, Department of Health Informatics and Public Health, Tohoku University School of Public Health, Graduate School of Medicine, Sendai, Japan.
authors: Yumi
authors: Y
authors: Sugawara
authors: Division of Epidemiology, Department of Health Informatics and Public Health, Tohoku University School of Public Health, Graduate School of Medicine, Sendai, Japan.
authors: Yasutake
authors: Y
authors: Tomata
authors: Division of Epidemiology, Department of Health Informatics and Public Health, Tohoku University School of Public Health, Graduate School of Medicine, Sendai, Japan.
authors: Takashi
authors: T
authors: Watanabe
authors: Division of Epidemiology, Department of Health Informatics and Public Health, Tohoku University School of Public Health, Graduate School of Medicine, Sendai, Japan.
authors: Ichiro
authors: I
authors: Tsuji
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D004190:Disasters; D055866:Earthquakes; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D012934:Social Isolation / Q000523:psychology*; D013315:Stress, Psychological / Q000453:epidemiology*; D011795:Surveys and Questionnaires; D017741:Survivors / Q000523:psychology* / Q000706:statistics & numerical data; D013997:Time Factors; D055815:Young Adult
keywords: Longitudinal study; Psychological distress; Social isolation; Victim