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Ageing
Impact of the 2011 Great East Japan Earthquake and Tsunami on functional disability among older people: a longitudinal comparison of disability prevalence among Japanese municipalities
  1. Yasutake Tomata1,
  2. Masako Kakizaki1,
  3. Yoshinori Suzuki2,
  4. Shuji Hashimoto3,
  5. Miyuki Kawado3,
  6. Ichiro Tsuji1
  1. 1Division of Epidemiology, Department of Public Health and Forensic Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan
  2. 2Faculty of Human Sciences, Department of Health and Nutrition, Sendai Shirayuri Women's College, Sendai, Japan
  3. 3Department of Hygiene, Fujita Health University School of Medicine, Toyoake, Japan
  1. Correspondence to Dr Yasutake Tomata, Division of Epidemiology, Department of Public Health and Forensic Medicine, Tohoku University Graduate School of Medicine 2-1, Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8575, Japan; y-tomata{at}med.tohoku.ac.jp

Abstract

Objective To examine the hypothesis that disability prevalence has increased to a greater degree in the areas severely affected by the earthquake and tsunami of 11 March 2011 than in other areas.

Methods Longitudinal analysis using public statistics data from the Ministry of Health, Labour and Welfare in Japan. The analysis included 1549 municipalities covered by the Long-term Care Insurance (LTCI) system. ‘Disaster areas’ were defined as three prefectures (Iwate, Miyagi, Fukushima). The outcome measure was the number of aged people (≥65 years) with LTCI disability certification. Rates of change in disability prevalence from February 2011 to February 2012 were used as the primary outcome variable, and were compared by analysis of covariance between ‘Coastal disaster areas’, ‘Inland disaster areas’ and ‘Non-disaster areas’.

Results Regarding disability prevalence at all levels, the mean value of the increase rate in Coastal disaster areas (7.1%) was higher than in Inland disaster areas (3.7%) and Non-disaster areas (2.8%) (p<0.001).

Conclusions The areas that were severely affected by the earthquake and tsunami had a significantly higher increase in disability prevalence during the 1 year after the earthquake disaster than other areas.

  • DISABILITY
  • DISASTER RELIEF
  • EPIDEMIOLOGY
  • GERONTOLOGY

https://doi.org/10.1136/jech-2013-203541

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    Background

    Natural disasters are known to have a chronic effect on the functioning of older persons.1 The Great East Japan Earthquake (GEJE) and tsunami on 11th March 2011 took the lives of more than 15 000 people, but also affected the health of survivors.2 ,3 To date, it has been reported that injury,4 cardiovascular diseases,5–7 pneumonia,2 ,8 post-traumatic stress disorder,9 ,10 and cognitive function decline11 have increased since the GEJE. These acute conditions might result in chronic changes in health and function status, that is, an increase in the incidence of functional disability. Because of aging of the global population, and the fact that older people are more vulnerable to disability, any increase in the disabled older population after a disaster would pose a large burden. To our knowledge, however, no study has yet addressed the hypothesis that the prevalence of disability is higher in a disaster area than in other areas.

    Long-term Care Insurance (LTCI) system in Japan is a standard unified nationwide certification system for disabled older persons. Because the numbers of individuals certified in each municipality are reported in the form of nationwide statistics every month, it is possible to compare the disability prevalence in the older population.

    The aim of the present study was to examine the hypothesis that the disability prevalence would have increased in the areas severely affected by the GEJE, relative to other areas of Japan.

    Methods

    Study design

    The authors performed an ecological study, using data from the Report on the Status of the LTCI Project, issued by the Ministry of Health, Labour and Welfare of Japan.12

    To confirm if the changes that occurred in the 1-year period after the GEJE were particularly bigger than those which occurred in the 1-year period before it, statistical data for the 26 months from February 2010 to March 2012 were collected. These data included the status of municipalities at the end of each month.

    All municipalities included in the LTCI system as of 31st March 2012 (n=1580) were defined as the study subjects. Because most municipalities become insurers in the LTCI system, the term ‘municipalities’ was used in the present study as an alternative term for ‘insurer’ in the LTCI system.

    Outcome

    Functional disability was defined according to disability certification in the LTCI system. Disability prevalence (%) in each municipality every month was calculated as the ‘number of persons who were certified for LTCI/number of insured elderly population aged ≥65 years’.

    The LTCI is a mandatory form of social insurance to assist the frail elderly in their daily activities.13 ,14 Every person aged >65 years is eligible for formal caregiving services. A person must be certified according to the nationally uniform standard to receive caregiving services in the LTCI system. If a person is judged to be eligible for benefits, the Municipal Certification Committee decides on one of seven levels of support, ranging from Support Levels 1 and 2 to Care Levels 1 through 5. In brief, the LTCI certification levels are defined as follows: Support Level 1 is defined as ‘limited in instrumental activities of daily living but independent in basic activities of daily living (ADL)’, Care Level 2 is defined as ‘requiring assistance in at least one basic ADL task’, and Care Level 5 is defined as ‘requiring care in all ADL tasks’. A community-based study has shown that levels of LTCI certification are well correlated with ability to perform ADLs, and with the Mini Mental State Examination score.15 LTCI certification has already been used as a measure of functional disability.16

    Statistical analysis

    Among all municipalities (n=1580), as one area had become amalgamated into a city as a result of municipal boundary change, these two areas were treated as a single subject (consequently, n=1579).

    The municipalities were excluded if: (1) any data from February 2010 to March 2012 had been rendered unavailable (n=15 in figure 1); (2) data had been recorded on the classification system used before April 2006 (n=2); or (3) the outcome variable (mild disability or moderate to severe disability) when stratified by the age structure of the population (65–74 years or ≥75 years) was 0% at any point, because it was a village where the population scale was particularly small (n=13). As a result, a total of 1549 subject municipalities were included in the analysis.

    Figure 1
    Figure 1

    Map of the disaster areas, coastal disaster areas, and areas for which data were not available, in relation to the epicenter of the GEJE. The area surrounded by the bold line was defined as ‘Disaster areas’ in the present study (Iwate, Miyagi, Fukushima). Among ‘Disaster areas’, the number of municipalities included in ‘Coastal disaster areas’ was 24 (black fill). The number of municipalities for which data were not available was 15 (diagonal).

    In the present study, ‘Disaster areas’ were defined to be municipalities in the prefectures of Iwate, Miyagi, and Fukushima, which were extensively damaged by the GEJE.4 Furthermore, the disaster areas were classified into ‘Coastal disaster areas’ and ‘Inland disaster areas’ in assessing the damage caused by the tsunami (figure 1). Additionally, ‘Non-disaster areas’ were defined as the municipalities in the other 44 prefectures in Japan.

    The primary outcome was the rate of change in disability prevalence from February 2011 to February 2012 (eg, ‘5.0%’ means ‘1.05-fold’). The outcome was divided according to disability level into three patterns: ‘all’, ‘mild (Care Level ≤1)’ and ‘moderate to severe (Care Level ≥2)’. This cutoff was suggested by the previous study.17 Analysis of covariance was used for estimating the adjusted means and 95% CI. The adjustment item was the proportion of persons ≥75 years with reference to all the insured elderly persons (%) at the baseline (February, 2011).

    Furthermore, the adjusted mean rates of monthly change in disability prevalence from February 2010 were calculated to verify that the increase of disability prevalence had been particularly marked after the GEJE.

    All data were analysed using IBM SPSS V.20 (IBM Software Group, Chicago, Illinois, USA). All statistical tests described were two-sided, and differences at p<0.05 were accepted as significant.

    Results

    Baseline characteristics

    The baseline characteristics in February 2011 were as follows (see online supplementary table S1). The mean (SD) number of insured elderly persons aged ≥65 years was 22 251 (39 990) in the Coastal disaster areas, 10 081(14 360) in the Inland disaster areas, and 19 082 (41 630) in the Non-disaster areas (p=0.149 by ANOVA). The mean disability prevalence was 16.1% (1.3%) in the Coastal disaster areas, 16.7% (1.9%) in the Inland disaster areas, and 16.7% (2.8%) in the Non-disaster areas (p=0.578 by ANOVA).

    One-year change in disability prevalence

    The rates of change in disability prevalence after 1 year from the occurrence of the GEJE were compared between regions, and the results are shown in table 1. The disability prevalence at all levels increased by 2.8% in the Non-disaster areas and 3.7% in the Inland disaster areas. By comparison, the increase was 7.1% in the Coastal disaster areas (p<0.001).

    View this table:
    Table 1

    Regional comparisons of rates of change in disability prevalence during the 1 year following the month before the Great East Japan Earthquake (n=1549 municipalities)

    When stratified by the increase in the level of disability, the increase in mild disability in Coastal disaster areas (12.6%) was higher than in Inland disaster areas (4.8%) and Non-disaster areas (3.3%) (p<0.001). For the increase in moderate to severe disability, although that in Coastal disaster areas was higher than Non-disaster areas and the Inland disaster areas, the difference was not significant (p=0.190).

    Monthly change in disability prevalence

    The disability prevalence increased in each region from February 2010 to February 2011 (see online supplementary figure S1–S3). In the Coastal disaster areas, however, the disability prevalence decreased from February to May 2011, and afterwards showed a dramatic increase up to September 2011 in all the disability levels.

    Discussion

    The purpose of this study was to test the hypothesis that the disability prevalence would have increased more markedly after the GEJE in Coastal areas, where the damage was especially great, than in other areas. The results showed that the rate of change in disability prevalence was especially high in the Coastal disaster areas, even when compared with the inland areas of the same prefectures. This increasing trend in the Coastal disaster areas was particularly notable at the mild level.

    Additionally, the difference between the mild level and the moderate to severe level, with reference to the trend of the degree of increase, could not be explained by the decrease of disability prevalence in the Coastal disaster areas from February to May 2011, because this decrease was equal between the mild-to-moderate level and the moderate-to-severe level (crude change ratio; −5.7% vs −4.3%, data not shown).

    Many elderly people died, or were moved by the GEJE. Therefore, the disability prevalence might have increased even if the number of the disabled elderly had not increased. To confirm this, we examined the changes in the number of the elderly (insured persons) and the disabled elderly persons in the Coastal disaster areas from February 2011 to February 2012. We found that, while the number of the elderly had decreased (crude change ratio; −2.7%, data not shown), the number of the disabled elderly had increased (crude change ratio; 4.2%, data not shown). Thus, we confirmed that the increase in the disability prevalence would not be explained solely by the decrease of the elderly population.

    The mechanism responsible for the sharp increase in the disability prevalence in the Coastal disaster areas was thought to be, first, the above-mentioned problems of older disaster victims themselves, such as injury, cardiovascular diseases and mental disorders, which promote the development of disability, and second, functional decline due to reduced physical activity and restrictions on activities caused by environmental changes (the destruction of infrastructure and facilities, etc.) resulting from the disaster.18 Other possibilities include social factors such as being compelled to use LTCI services due to the loss of social support (family support, etc.) for persons who already had reduced levels of function before the disaster.

    The reason for the decrease in disability prevalence in the Coastal disaster areas during March–May 2011 as shown in Figures S1–S3 was thought to be threefold. One of these reasons could be the deaths of aged people, especially those with disabilities, who were unable to escape the tsunami. In fact, individuals aged ≥65 years accounted for 56.7% of the death toll from the GEJE in the disaster areas.19 Additionally, the displacement and relocation of the aged people, especially those with disabilities, may have contributed to this decrease. In fact, the Ministry of Health, Labour and Welfare of Japan had requested the local governments to accept the disabled elderly persons, and 36 392 people became eligible to receive the facilities for the elderly persons. However, only less than 1300 elderly persons were relocated to the other prefectures on 25th May 2011 (the total number of people with a disability was 88 554 and 135 060, in the coastal disaster areas and non-coastal disaster areas, respectively, in February 2011).20 Finally, the delay in the LTCI certification process could have been the third reason. This may have occurred due to the administrative overload right after the GEJE. However, the data required to examine the impact of these factors were not available.

    This study had several limitations. First, postdisaster data for some areas where the damage was particularly great were not obtained, because regional government offices were not functional (n=15). Among the above, 11 areas in Fukushima prefecture were impacted mainly by the nuclear accident at Fukushima Daiichi atomic power plant. Municipalities with particularly marked increases in the numbers of people with disabilities might not have been included in the analysis; therefore, it is possible that the results of this study might have underestimated the increase in disability prevalence in Coastal disaster areas. Second, the causes of functional disability were not investigated. Thus, the mechanism remained unidentified.

    In conclusion, the degree of increase in disability prevalence in the year around the time of the GEJE was found to be significantly higher in the Coastal areas that suffered damage than in other areas.

    What is already known on this subject

    • Natural disasters chronically affected the functioning of older persons.

    • Health problems, such as injury, cardiovascular diseases and post-traumatic stress disorder have increased in the disaster-stricken areas since the Great East Japan Earthquake and tsunami.

    What this study adds

    • This study clarified the whole impact that the disaster increased functional disability in older people. Specifically, the Great East Japan Earthquake and tsunami posed a large burden due to long-term increase of disabled older person in wide-ranging areas.

    Acknowledgments

    We would like to thank Yoshiko Nakata, Yumi Tamura and Yukiko Asano for their technical assistance.

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    View Abstract

    Supplementary materials

    • Supplementary Data

      This web only file has been produced by the BMJ Publishing Group from an electronic file supplied by the author(s) and has not been edited for content.

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    Footnotes

    • Contributors YT designed the study, performed the statistical analyses and wrote the first draft of the manuscript text. MK, YS, SH and MK helped design the study and contributed to the interpretation of the results. IT has supervised and provided commentaries to the manuscript text and helped interpret the results.

    • Funding This work was supported by Health Sciences Research grants (H24-Toukei-Ippan-006, H25-Kenki-Shitei-002[fukkou]) from the Ministry of Health, Labour and Welfare of Japan.

    • Competing interests None.

    • Ethical approval Because this study used public statistical data at the municipal level, personal informed consent was not considered necessary.

    • Provenance and peer review Not commissioned; externally peer reviewed.