Predictors of decline in IADL functioning among older survivors following the Great East Japan earthquake: A prospective study

Introduction We described associations between the type of disaster experience and change in instrumental activities of daily living among older adult survivors before-after a terrible disaster. Methods The study took advantage of a “natural experiment” afforded by the Japan Gerontological Evaluation Study (JAGES), a nationwide cohort study established in 2010, seven months prior to the earthquake and tsunami. A follow-up survey was conducted in 2013. This study was conducted in Iwanuma, which was directly struck by tsunami. Our sample comprised community-dwelling aged survivors in Iwanuma who responded to questions about personal circumstances and functional status both before and after the disaster (N = 3547). Personal experiences of earthquake and tsunami damage was used as an exposure variable. The outcome was changes in self-reported 13-item instrumental activities of daily living (IADL), which was assessed both before and after the disaster. Results Among the participants, 931 reported losing family member(s) to the disaster, while a further 549 reported losing friend(s). More than half of the participants reported any damage to their houses while approximately 1 in 8 lost their car(s). The multivariable OLS regression revealed that complete house loss and disruption of internal medicine were associated with significantly worse IADL: −0.67 points (95%CI: −0.99, −0.34) for entirely destroyed homes; −0.40 points (95% CI: −0.71, −0.092) for disruption of internal medicine. By contrast, loss of family/friends/pets/cars and disruption to the other medical service were not associated with decline in IADL. Conclusion Complete house loss and disruption of access to internal medicine after a disaster were associated with significant adverse impact on decline in physical and cognitive functions 2.5 years after the disaster, while loss of family/friends was not.