The characteristics of non-respondents and respondents of a mental health survey among evacuees in a disaster: The Fukushima Health Management Survey.

The Fukushima Medical University conducted a mental health care program for evacuees after the Fukushima Daiichi nuclear power plant accident. However, the mental health status of non-respondents has not been considered for surveys using questionnaires. Therefore, the aim of this study was to clarify the characteristics of non-respondents and respondents. The target population of the survey (FY2011-2013) is people living in the nationally designated evacuation zone of Fukushima prefecture. Among these, the participants were 967 people (20 years or older). We examined factors that affected the difference between the groups of participants (i.e., non-respondents and respondents) using multivariate logistic regression analysis. Employment was higher in non-respondents (p=0.022) and they were also more socially isolated (p=0.047) when compared to respondents; non-respondents had a higher proportional risk of psychological distress compared to respondents (p<0.033). The results of the multivariate logistic regression analysis showed that, within the participants there was a significant association between employment status (OR=1.99, 95% confidence interval [CI]:1.12-3.51) and psychological distress (OR=2.17, 95% CI:1.01-4.66). We found that non-respondents had a significantly higher proportion of psychological distress compared to the respondents. Although the non-respondents were the high-risk group, it is not possible to grasp the complexity of the situation by simply using questionnaire surveys. Therefore, in the future it is necessary to direct our efforts towards the mental health of non-respondents and respondents alike.