Period of residence in prefabricated temporary housing and psychological distress after the Great East Japan Earthquake: a longitudinal study

Objectives Previous studies have reported that displacement from one's own home after a natural disaster is associated with a higher degree of psychological distress. The present study investigated the longitudinal association between the period of residence in prefabricated temporary housing and psychological distress after the Great East Japan Earthquake. Design, setting and participants We conducted a longitudinal observation of 284 adults (aged >= 8 years) who had lived in prefabricated temporary housing in Miyagi, Northeastern Japan. The period of residence in prefabricated temporary housing was classified into three categories: <3, 3-4 and >4 years (ie, still living in prefabricated temporary housing). Outcomes The Kessler 6-item Psychological Distress Scale (K6) was assessed in both a baseline survey (2011) and a follow-up survey (2016). Higher psychological distress was defined by a K6 score of >= 5. We used Firth's penalised likelihood method in the multivariate logistic regression model to estimate the adjusted ORs and 95% Cls. Results Among the total participants, the proportion of individuals with higher psychological distress at the follow-up survey was significantly higher in the >4 years category (multivariate OR=4.00, 95% CI 1.67 to 10.16) than in the <3 years category. Among participants who had a lower degree of psychological distress at the baseline, the proportion of those whose psychological distress deteriorated was significantly higher in the >4 years category (multivariate OR=4.87, 95% CI 1.26 to 20.28) than in the <3 years category. On the other hand, among the participants who had a higher degree of psychological distress at the baseline, the proportion of those whose psychological distress ameliorated was significantly lower in the >4 years category (multivariate OR=0.26, 95% CI 0.06 to 0.85) than in the <3 years category. Conclusions The proportion of individuals with more severe psychological distress was higher among participants who had lived in prefabricated temporary housing for a long period.