[Falls and associated risk factors among elderly survivors of the Great East Japan Earthquake: RIAS Study].

Objective　An increasing incidence of disuse syndrome is commonly observed in areas affected by large-scale natural disasters. Consequently, the fall risk is high in such populations, necessitating adequate attention to fall prevention measures. It is important to identify factors associated with falls to prevent deterioration in functional ability. We investigated the risk factors associated with falls among elderly survivors in disaster-stricken areas using longitudinal data from the Research project for the prospective Investigation of health problems Among Survivors of the Great East Japan Earthquake (RIAS) Study.Methods　Of all data obtained from the RIAS Study, we used the data of 1,380 survivors who were aged ≥65 years, were not diagnosed with cancer or cardiovascular disease, did not need supportive care, and could participate in the annual survey between 2011 and 2016. Self-administered questionnaires were distributed, and anthropometric and grip tests were performed during the 2011 survey to obtain information regarding housing damage, the fear of falls, arthralgia, cognitive function psychological distress, insomnia, frequency of leaving the house, a history of hypertension, dyslipidemia, diabetes, alcohol consumption status, smoking status, and/or body mass index, and grip strength. Based on the responses obtained from each annual survey, a fall was defined as an event during which an individual had fallen at least once. Multivariate-adjusted odds ratio(OR) and 95% confidence interval(CI) for all variables related to falls were calculated using logistic regression with adjustment for sex and residential area. Similar analyses were performed based on age groups (65-74 years and ≥75 years).Results　The 5-year fall incidence rate was 35.5% (31.9% [men], 37.9% [women]). In men, cognitive dysfunction was significantly associated with falls (OR 1.50, 95%CI 1.01-2.22). In women, cognitive dysfunction (OR 1.82, 95%CI 1.34-2.47), insomnia (OR 1.41, 95%CI 1.02-1.94), dyslipidemia (OR 1.58, 95% 95% CI 1.11-2.25), and a history of smoking (OR 4.30, 95%CI 1.08-17.14) were significantly associated with falls. In women aged ≥75 years, partial housing damage (OR 7.93, 95%CI 1.85-33.91) and psychological distress (OR 2.83, 95%CI 1.09-.7.37) were also significantly associated with falls.Conclusion　This study suggests that cognitive dysfunction in both sexes and insomnia, dyslipidemia, and a history of smoking in women were significantly associated with falls, and partial housing damage and psychological distress were risk factors for falls in women aged ≥75 years. Fall prevention after large-scale natural disasters warrants close attention to known risk factors and environmental and mental health changes.