What factors are associated with new social isolation years after the great East Japan Earthquake?: findings from the TMM CommCohort study.

BACKGROUND

The effects of disaster experiences on social isolation and related factors remain unclear. Using longitudinal data, this study aimed to identify new social isolation and its associated factors after the Great East Japan Earthquake (GEJE), which occurred on March 11, 2011.

METHODS

We analyzed longitudinal data from 12,795 participants who responded to self-report questionnaires, utilizing the Lubben Social Network Scale-6 (LSNS-6). Participants included 4,450 men and 8,345 women; the sex ratio of the analytic sample was broadly consistent with that of the study population at baseline. Baseline data were collected between fiscal years (FY) 2013 and 2015, and follow-up data were collected between FY2017 and FY2019. Social isolation was defined as a score < 12 on the LSNS-6. Based on their level of social isolation in the second survey, participants were categorized into two groups: not socially isolated and newly socially isolated. To examine factors associated with new social isolation, we used logistic regression analysis to calculate multivariate-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for the newly socially isolated group versus the not socially isolated group by sex.

RESULTS

New social isolation was associated with several lifestyle and psychosocial factors, exhibiting differences between men and women. Among men, factors associated with new social isolation were not currently smoking among those without house damage, living alone among those with house damage, and no exercise habits among those who experienced the death of family members due to GEJE. Among women who lost family members due to GEJE, insomnia was associated with new social isolation.

CONCLUSION

The occurrence of new social isolation years after the GEJE and its associated factors varied by sex and the presence of GEJE-related damages. To prevent new social isolation in the aftermath of a large-scale natural disaster, it is crucial to consider sex-specific factors contributing to social isolation.