The East Japan earthquake of March 11, 2011, with a magnitude of 9.0, was the most powerful earthquake in Japan on record. The earthquake and the tsunami that followed resulted in immense damage. A hydrogen explosion at the Fukushima-Daiichi nuclear plant resulted in the contamination of a large area. The Japanese government reported that 335,000 people, including 95,000 in Fukushima, were evacuated.

The following month, 280 residents with intellectual disabilities and 80 caregivers at nine facilities in Fukushima were evacuated and moved to Kamogawa, located about 190 miles away from the nuclear plant in the prefecture of Chiba. In Fukushima, there were 46 facilities for residents with intellectual disabilities in total before the earthquake. In Chiba, the 280 individuals evacuated from Fukushima stayed in a facility on a hill near the coast that was originally intended for youths. Because the facility contained many bunk beds and windows that easily opened, it required renovation to keep residents safe. The caregivers were separated from their family in Fukushima and had few friends to rely on. In addition, they were worried about deciding to give their work priority over their family and friends. Caring for and supporting the residents were extremely difficult for the caregivers because of their high level of physical and emotional stress.

To investigate the impact of the earthquake and the subsequent evacuation on the caregivers’ burden, we sent questionnaires to the caregivers from Fukushima and to caregivers at an equivalent facility in Chiba who were not forced to evacuate.

This was a cross-sectional study. Caregivers who had been evacuated from the nine facilities in Fukushima (N=58) and at three nonevacuated facilities in Chiba (N=62) were mailed surveys between the middle of August 2011 and the beginning of January 2012. Several psychiatrists had independently determined that the Fukushima and Chiba facilities provided an equivalent level of care for disabled persons. The participants were all over the age of 20 years old. The survey included the 12-item General Health Questionnaire (GHQ-12) and additional questions about the participants’ gender, age, years of employment, quality of sleep, and drinking and smoking habits (1–3). Global scores on the GHQ-12 range from 0 to 12, with higher scores indicating greater severity (4). We used a standard drink equivalent of 10 grams of ethanol to reflect daily alcohol consumption.

Questionnaires were returned by 48 (83%) caregivers from Fukushima and 48 (77%) caregivers from Chiba. After excluding anonymous responders and responders who returned incomplete documents, the sample included 46 participants (23 males and 23 females) from Fukushima and 46 participants (26 males and 20 females) from Chiba, with mean ages of 43.93±11.23 years and 39.80±12.88 years, respectively. The study protocol was approved by the Kameda General Hospital Institutional Review Board. After a complete description of the study was provided to the participants, written informed consent was obtained.

All data were screened for normality, homogeneity of variance, and outliers. We performed a Mann-Whitney U test to examine the groups for differences in the GHQ-12 global scores, which were not normally distributed. Correlation coefficients were calculated for demographic variables (gender and age) and relevant clinical variables (evacuation or no evacuation, years of employment, and higher GHQ-12 global score). According to a previous study performed in Japan, we used 3 as the cut-off for the GHQ-12 global score and a score of ≥3 to indicate psychiatric morbidity (5). We considered a score of 8, equal to the 75th percentile of the distribution, to indicate a more severe condition. We set the correlation coefficient at ≥.5 to be considered strongly correlated with one another (collinearity). The variables were not strongly correlated with one another in this case.

A logistic regression analysis was performed by using a higher GHQ-12 score as the dependent variable and gender, age, years of employment, and evacuation as the covariates. Thereafter, we performed a chi square test comparing each item of the GHQ-12 and the presence of evacuation. Next we divided the GHQ-12 items into two groups that have been associated with psychological distress (items 2, 5, 6, 9, 10, and 11) and social dysfunction (items 1, 3, 4, 7, and 8) in the general Japanese population (6). We performed the median tests to examine the caregiver groups for differences in the GHQ-12 integrated score for each factor. Statistical significance was set at p<.05. All tests were two sided, and all of the statistical analyses were conducted by using the SPSS, version 18.0, software program.

The mean values for the GHQ-12 global scores were 6.17±4.14 for the evacuated group and 3.54±3.26 for the nonevacuated group. A statistically significant difference was found for the presence of evacuation and a GHQ-12 global score ≥3 (χ²=3.94, df=1, p=.047). There were no statistically significant differences between the participants with regard to the presence of evacuation and the categorical variables of gender, quality of sleep, and frequency of drinking and smoking.

According to the Mann-Whitney U tests, caregivers from Fukushima had a significantly higher mean GHQ-12 global score (p<.01) than the caregivers from Chiba. The results from the logistic regression analysis indicated that the presence of evacuation produced a statistically significant relative risk (RR) of a GHQ-12 global score ≥3 (RR=2.81, 95% confidence interval [CI]=1.06–7.48, p=.04). In addition, a GHQ-12 global score ≥8 was linked to evacuation (RR=3.57, CI=1.24–10.24, p=.02).

There were statistically significant differences between the presence of evacuation and items 1, 2, 3, 7, and 12 of the GHQ-12 (Table 1). Compared with caregivers from Chiba, the caregivers from Fukushima had a significantly higher GHQ-12 integrated score for the items related to social dysfunction (p<.001). By contrast, there was no statistically significant difference between the two groups on items related to psychological distress.

In this study, the presence of evacuation was the basis of increased emotional stress among caregivers. In particular, there was a trend for the evacuated caregivers to have more social dysfunction than psychological distress.

Moreover, the evacuation itself was probably not the only factor affecting the differences in the GHQ-12 global scores. Caregivers from Fukushima had lost their homes and loved ones and had family members who had been injured and who continued to be exposed to the elevated level of radiation in Fukushima. It is important to ensure that going forward, caregivers from the evacuated facilities receive adequate rest and compensation and that facilities be adequately staffed to allow caregivers to assist disabled persons should another disaster occur.

The psychological stress after a large-scale disaster, such as an earthquake, continues for a long period (7,8). Furthermore, the burden on the caregivers at nursing homes in Japan was already problematic before the disaster (9–11) because of long working hours and low pay, which led to a shortage of such caregivers.

According to Doi and Minowa (6), the mean GHQ-12 global score among Japanese men and women aged 30 to 39 years was 2.83±3.05 and 3.14±2.97, respectively. In this study, the mean GHQ-12 global score for participants from the nonevacuated facilities (mean=39.8 years) was 3.54±3.26. Compared with the general Japanese population, even these workers had higher GHQ-12 scores. This finding is consistent with the increased emotional stress experienced by the caregivers.

There are limitations to the methodology of this study. First, the sample size was limited to a nonrandomized and unmasked sample of 92 participants. Therefore, the results of this study cannot be generalized beyond the sample. Also, no causal relationship could be determined because of the cross-sectional nature of the study.

This study demonstrated a statistically significant difference between the emotional stress of the caregivers and evacuation following an earthquake. A future follow-up study should focus on the influence of time on the caregiver burden.

The authors report no competing interests.