福島県立医科大学 学術機関リポジトリ

Title

Socioeconomic status, damage-related conditions, and PTSD
following the Fukushima-daiichi nuclear power plant
accident:The Fukushima Health Management Survey

Author(s)Shiga, Tetsuya; Zhang, Wen; Ohira, Tetsuya; Suzuki, Yuriko;
Maeda, Masaharu; Mashiko, Hirobumi; Yabe, Hirooki; Iwasa,
Hajime; Nakano, Hironori; Yasumura, Seiji; Kamiya, Kenji;
Fukushima Health Management Survey Group

Citation

Fukushima Journal of Medical Science. 67(2): 71-82

Issue Date

2021

URL

http://ir.fmu.ac.jp/dspace/handle/123456789/1587

Rights© 2021 The Fukushima Society of Medical Science. This
article is licensed under a Creative Commons [AttributionNonCommercial-ShareAlike 4.0 International] license.

DOI

10.5387/fms.2020-24

Text Version publisher

This document is downloaded at: 2024-10-16T09:26:33Z

Fukushima Medical University

Fukushima J. Med. Sci.,
Vol. 67, No. 2, 2021

PTSD and related factors
after a disaster[Original article]

Socioeconomic status, damage-related conditions, and
PTSD following the Fukushima-daiichi nuclear power plant accident :The Fukushima Health Management Survey
Tetsuya Shiga1)2)3), Wen Zhang3)4), Tetsuya Ohira3)4), Yuriko Suzuki5), Masaharu Maeda3)6),
Hirobumi Mashiko1)3), Hirooki Yabe1)3), Hajime Iwasa3)7), Hironori Nakano3)4),
Seiji Yasumura3)7) and Kenji Kamiya3)8),for the Fukushima Health Management Survey Group1)

Department of Neuropsychiatry, Fukushima Medical University, 2)Aizu Medical Center, Fukushima
Medical University, 3)Radiation Medical Science Center for the Fukushima Health Management Survey,
Fukushima Medical University, 4)Department of Epidemiology, Fukushima Medical University, 5)Department of Adult Mental Health, National Institute of Mental Health, National Center of Neurology andPsychiatry, 6)Department of Disaster Psychiatry, Fukushima Medical University, 7)Department of Public
Health, Fukushima Medical University, 8)Research Institute for Radiation Biology and Medicine, Hiroshima University(Received November 12, 2020, accepted July 15, 2021)
Abstract
The Great East Japan Earthquake severely damaged the Tohoku and Kanto districts, and Fukushima
Prefecture faced a subsequent nuclear disaster. Few studies have reported the effects of socioeconomic stressors on individuals’ mental status following disasters. We analyzed the responses of
60,704 adult residents of a designated restricted area to the PTSD Checklist-Stressor-Specific Version (PCL-S). The relationships between the PCL-S scores and demographic, socioeconomic, anddamage-related variables were analyzed using regression analysis to predict participants’ severity of
PTSD symptoms. Approximately 14.1% of evacuees had severe PTSD symptoms (PCL-S ≥50)
eighteen months post-earthquake. The PCL-S scores were higher among women, older adults,
less educated people, those with a history of mental illness, and those living outside Fukushima Prefecture. The PCL-S scores increased with participants’ scores on the Kessler Psychological Distress Scale. The number of trauma-exposure stressors and socioeconomic stressors were associated with 1.52 and 3.77 increases in the PCL-S score, respectively. Furthermore, psychologicaldistress, unemployment, decreased income, house damage, tsunami experience, nuclear power plant
accident experience, and loss of someone close due to the disaster were associated with the prevalence of severe PTSD symptoms. The complex triple disaster of a major earthquake, tsunami, andnuclear accident created significant socioeconomic changes that may be important determinants of
PTSD among residents of restricted access areas in Fukushima.
Key words : post-traumatic stress disorder, depression, cross-sectional study, population, theGreat East Japan Earthquake

Corresponding author : Tetsuya Ohira, MD, PhD.   E-mail : teoohira@fmu.ac.jp©2021 The Fukushima Society of Medical Science. This article is licensed under a Creative Commons [Attribution-NonCommercial-ShareAlike 4.0 International] license.
https://creativecommons.org/licenses/by-nc-sa/4.0/
71

71

T. Shiga et al.

72

Introduction
The Great East Japan Earthquake of March 11,2011 had a recorded moment magnitude (Mw) of 9.0.
The seismic center was approximately 130 kilometers southeast of the Oshika Peninsula, Miyagi Prefecture. This earthquake triggered a huge tsunamithat severely damaged the Pacific coast of both the
Tohoku and Kanto districts. The number of deadand missing people due to the earthquake and tsunami is, as of now, over 18,000, with over 400,000 houses partially or totally destroyed1). The Fukushima
Daiichi Nuclear Power Plant, located on the borderof Okuma Town and Futaba Town, Fukushima Prefecture, lost redundant sources of power due to theearthquake and tsunami, which led to a Level 7 (major) nuclear accident, as measured on the International Nuclear Event Scale, according to the International Atomic Agency (IAEA) 2) . The nuclear
reactor meltdown and resultant hydrogen explosions
caused radioactive contaminants to spread over large
areas, mainly in Fukushima Prefecture. As a result,
Fukushima residents have experienced long-term
environmental effects of these radioactive substances.
Studies of past nuclear accidents, such as Chernobyl and Three Mile Island, have indicated that themost critical health problems caused by such accidents were mental-health issues3,4). Among those
who lived in areas exposed to radiation, there was ahigher prevalence of depression, anxiety (including
posttraumatic symptoms), and medically unexplained physical symptoms5). Likewise, the World
Health Organization (WHO) concluded that mentalhealth problems were the most serious of all of thehealth problems following the 2011 disaster in Japan6).
Because Fukushima residents experienced a
triple disaster of earthquake, tsunami, and nuclear
accident, many of them had no choice but to evacuate their hometowns, and many remained evacuees
three years later. The living conditions of theseevacuees in the future remain uncertain. Psychiatric epidemiological surveys following past disasters
have revealed a number of risk factors for disastervictims7). In this triple disaster, however, the added
possibility of health distress due to radiation exposure likely affected residents’ long - term mental
health considerably, in addition to the previously
identified risk factors. Even medical assistanceteam-workers showed psychological distress concerning radiation exposure after March 20118).
Many surveys have revealed that survivors ofnatural disasters, such as earthquakes and tsunamis,
often present with posttraumatic stress disorder(PTSD). However, for man-made disasters, suchas the Chernobyl nuclear reactor accident and the
9/11 World Trade Center terrorist attacks, studies
have found that PTSD occurs in both local residents
and disaster-relief workers3,4).
As long-term mental-health care was considered important for increasing survivors’ capacity forresilience in post-Fukushima recovery, an epidemiological survey (the “Mental Health and Lifestyle
Survey”) was conducted as part of the Fukushima
Health Management Survey. It aimed to ascertain
the psychological consequences that followed thisnuclear accident and to provide appropriate care to
the Fukushima residents9). This study’s purpose
was twofold : (1) to examine the relationships between PTSD symptoms and socioeconomic status
and damage-related situations using data obtained
from the Fukushima Health Management Survey of
Fiscal Year 2011, and (2) to identify possible directions for future studies and support implementation
efforts.

Materials and methods
DesignThis study analyzed data from the initial year of
the Fukushima Health Management Survey conducted 18 months after the earthquake, administered to Fukushima residents who survived theearthquake and faced mandatory evacuation fromtheir residence because of the Fukushima Daiichi
Nuclear Power Plant accident. This cross-sectional
health survey was used to assess effects of the nuclear accident and accompanying changes in living
status experienced by these long- term refugees.
The survey’s details are provided in Yasumura etal.9). In the present cross-sectional study, we useddata from adults (15 years old and over at the time ofthe earthquake) who completed the Fukushima
Health Management Survey 18 months after the disaster.
This survey and study were approved by the
Ethics Committee of Fukushima Medical University(#1316).
Participants
The survey population consisted of 210,189 officially registered residents of a nationally designated restricted area ; all of them were identified as
candidates for participation in the survey. The

PTSD and related factors after a disasternumber of adults born before April 1, 1995, was180,604 (88,085 men and 92,519 women ; 78,245
persons were aged 15-49 years ; 49,139 were aged
50-64 years ; and 53,220 were 65 years and above).
The registered earthquake restricted area included
13 municipalities : Hirono Town, Naraha Town, Tomioka Town, Kawauchi Village, Okuma Town, Futaba
Town, Namie Town, Katsurao Village, Iitate Village,
Minamisoma City, Tamura Town, Kawamata Town,
and part of Date City.
Figure 1 shows this study’s participant selection process. We mailed 180,604 questionnaires
from the end of January to the beginning of February
2012, to house addresses that were current at thetime of the survey, regardless of whether the present address was inside or outside of Fukushima Prefecture. By the end of October 2012, 73,569 questionnaires were returned with responses (40.7%
response rate) and 70,193 of these questionnaires(95.4%) had been returned by the end of March
2012. Of these, 12,865 were excluded from theanalysis (136 were blank or duplicates ; 9,245 werecompleted by a proxy, and 3,484 had more than one
missing value on the PTSD Checklist-Stressor Specific Version [PCL-S]). If there was only one PCLS value missing, we substituted the missing value
with the average value of the 16 remaining items.
In all, we used data from 60,704 participants (26,752

Figure 1.

Flowchart of the study’s target population.

73

men and 33,952 women ; 22,505 respondents wereaged 15-49 years ; 19,542 were 50-64 years ; 18,657
were 65 years and above) (Table 1). The response
rates of each restricted area were 35.1% in Hirono,
42.1% in Naraha, 45.0% in Tomioka, 43.3% in Kawauchi, 48.0% in Okuma, 50.0% in Futaba, 51.8% in Namie, 53.4% in Katsurao, 41.6% in Iitate, 40.4% in
Minamisoma, 31.2% in Tamura, 37.7% in Kawamata,and 39.9% in part of Date ; comparatively higher response rates are associated with municipalities
around the nuclear power plant.
Data collection and measurements
PTSD Checklist-Stressor Specific Version.
The PCL-S was used to evaluate PTSD symptoms.
This scale is a 17-item self-report checklist basedon the Diagnostic and Statistical Manual of Mental
Disorders, 4th edition (DSM-IV) criteria10), and each
item is rated using a Likert-type scale from 1 (not atall) to 5 (extremely)11). Respondents are requested
to answer all items by indicating the degree to which
they have experienced various PTSD symptoms
over the past month. The total PCL-S score, whichis calculated by summing the ratings for each item,
ranges from 17 to 85.
In addition to the PCL-S, the following items
were included on the self-assessment and self-report questionnaires.
Demographic and background char­ac­ter­is­tics. The participants’ characteristics were sex,
age group, educational attainment, history of mental
illness, and mental-health status. Age groups weredivided into childbearing age (15-49 years), middle
age (50-64 years), and old age (65 years and above).
Educational attainment was divided into elementary
school or junior high school (≤9 years education),high school (10-12 years education), vocational college or junior college (13-15 years education), anduniversity or graduate school (≥16 years education).
Mental-health status (non-specific psychological distress) was evaluated using the Kessler Psychological Distress (K6) Scale12). The validation of
the Japanese version has been reported previously13,14).
Socioeconomic variables. The socioeconomic variables included type of work and changes
in work situation after the earthquake. A “Yes” answer to the latter question indicated that the person
started a new job, became unemployed, changed
jobs, or experienced an increase or decrease in income.
Disaster-related variables. The disasterrelated variables consisted of current residence (in-

T. Shiga et al.

74

Table 1. Subject Characteristics by Sex and Age Groups.

Sex

Age group
Total

All residents (%)

All respondents (%)

Those who were analyzed (%)

Men
Women

88,085 (48.8%)
92,519 (51.2%)

32,301 (43.9%)
41,132 (55.9%)

26,752 (44.0%)
33,952 (55.9%)

15-49 years

78,245 (43.3%)
49,139 (27.2%)
53,220 (29.5%)

25,027 (34.0%)
21,340 (29.0%)
27,066 (36.8%)

22,505 (37.1%)
19,542 (32.2%)
18,657 (30.7%)

180,604

73,56960,70450-64 years
65 years and above

Among 180,604 persons who were mailed questionnaires in this survey, 73,569 responded (response rate
were 40.7%). 60,704 were analyzed after exclusion criteria were applied.

side or outside Fukushima Prefecture), classificationof house damage, as certified by the government (nodamage, partial damage, partial collapse, partial but
extensive collapse, and total collapse), living arrangement at the time of the survey (evacuation
shelter, temporary housing, rental housing/apartment, relatives’ home, and own home), experiencing
the tsunami, experiencing the nuclear power plant
accident (defined as hearing the explosion), and losing someone close because of the disaster.
Data analysis
The focus of the data analysis was the participants’ answers to the survey (N = 60,704). First,
we compared the PCL-S score with the median andthe interquartile range. Using age- and sex-adjusted analysis of covariance (ANCOVA), log - transformed PCL-S scores were then compared by age,sex, years of education, history of mental illness,and municipality. Dunnett’s procedure was used totest for significant differences between each category. Log-transformed PCL-S scores were also compared by socioeconomic- and disaster-related variables using ANCOVA adjusted for age and sex. The
Dunnett’s procedure was also used to test for significant differences between each category after ANCOVA. For age grouping, the analysis was conducted by first dividing the population into twogroups (the labor force at 15-64 years old and theparticipants ≥65 years old), and then dividing the15-64 age group into two groups at approximately
the median age (50 years).
Multivariate-adjusted regression analyses wereused to predict PCL-S point increases, based on the
background variables of the respondents (sex [women = 0, men = 1], age [continuous variable], historyof mental illness [No = 0, Yes = 1], educational status [elementary or junior high school = 0, high school= 1, vocational school or junior college = 2, university or graduate school = 3], residence [outside Fu-

kushima Prefecture = 0, inside Fukushima Prefecture = 1]). We also conducted regression analysis
to predict PCL-S scores by mental-health status, asmeasured by the K6 Scale (continuous variable).
Three new variables were also created to examine
the effect of multiple disaster stressors. The newvariables were defined as the sum of (1) the traumaexposure stressors, (2) the displacement stressorsand (3) the socioeconomic stressors, all considered
to be major stressors15). Thus, the trauma-exposure
stressors consisted of experience of the tsunami(Yes/No), experience of the nuclear power plant accident (Yes/No), and the loss of someone close because of the disaster (Yes/No). The displacement
stressors consisted of house damage (less than partial collapse/partial collapse and worse) and living
arrangements (own house/other than own house).
The socioeconomic stressors consisted of decreased
income (Yes/No) and unemployment (Yes/No).
These socioeconomic- and disaster-related factors
were incorporated into the variables by referring toprevious reports13,15,16). The regression analyses
were also performed on the newly created variables.
The interaction of trauma-exposure stressors, displacement stressors and socioeconomic stressors
were estimated by analysis of variance using generalized linear model. Since the PCL-S cutoff scoreof 50 was used to determine PTSD prevalence, as
recommended by Weathers et al.17), a PCL-S score of≥50 was defined as having provable PTSD, and thesocioeconomic- and disaster-related factors related
to provable PTSD were examined by multivariateadjusted modified Poisson regression analysis.
Data were analyzed with SAS, version 9.4, statistical software package (SAS Institute, Cary, NC,
USA). All probability values for the statistical tests
were two- tailed, with p values <0.05 considered
statistically significant.

PTSD and related factors after a disasterof the high PCL - S scorers differed between thegroups.

Results
Figure 2 shows the distribution of PCL - S
scores, which was positively skewed with a medianof 29. When the PCL- S cut- off score of 50 wasused as a threshold for provable PTSD, the total
number of PCL-S high scorers (PCL-S ≥50) was
9,037 (14.1% of the number of surveys analyzed, i.e.,the study sample). The demographic and background characteristics, socioeconomic and disasterrelated variables, and the PCL-S scores (with themedians and the inter-quartile ranges) are presented
in Tables 2 and 3.
Demographic and background characteristics
The median PCL- S score was higher among
women compared to men (Table 2). The median
PCL-S score was highest for the oldest group andlowest for the youngest group. People who had ahistory of mental illness were more likely to have ahigh PCL-S score.
Socioeconomic variables
Concerning type of employment, the median
PCL S score was lower among full-time employees
than either part-time employees or the unemployed(including students and full-time homemakers) (Table 3). More than half of the participants experienced a change in work situation, and the median
PCL- S score differed between these two groups.
As for loss of employment, the median PCL-S score
differed between the groups, as was the case of jobchange. Regarding increased income, the median-Figure 2.

75

Disaster-related variables
More than 80% of the individuals reported living in Fukushima Prefecture. The median PCL-S
score was higher for people living outside of Fukushima Prefecture (Table 3). The median PCL- S
scores for those living in a shelter were higher thanfor the others. The median PCL- S scores werehigher among people who had experienced the tsunami, the nuclear power plant accident, and lost
someone close due to the disaster, compared withpeople who had not.
Regression analysis
As shown in Table 4, the PCL - S score washigher among women, older participants, and lesseducated participants. The PCL-S score also wassignificantly related to a history of having a mental
disorder. As compared to participants who had no
previous mental illness, the estimated parameter(EP) for those who reported a prior mental disorder
was 4.29 for the multivariate-adjusted model. The
median PCL-S score was lower for participants living inside Fukushima Prefecture. As compared to
the refugees living outside Fukushima, the EP for
participants living inside it was −1.23 in the multivariate-adjusted model. Regarding mental-healthstatus, a 1.81 increase in PCL-S score was associated with a one point increase in the K6 score in themultivariate-adjusted model.
Table 4 also shows that the PCL - S score in-Distribution of PCL-S scores by age among men and women

T. Shiga et al.

76
Table 2.

The Associations of Participants’ Demographic and Background Characteristics with PTSD Severity.
Total

Sex
Men
Women
Age (years)
15-49
50-64
≥65
Education level
Elementary or junior high school
High school
Vocational school or junior college
University or graduate school
History of mental illness
Yes
No
Residence area as of March 11, 2011
HironoNarahaTomioka
KawauchiOkuma
FutabaNamie
Katsurao
IitateMinamisouma
TamuraKawamata
Part of Date b
th

th

th

PCL-S
Median 25th 75th

ANCOVAp-value

Number

%

Mean

SD

26,752
33,952

44.1
56.0

31.11
34.51

0.09
0.08

27
30

20
22

38
43

<0.001

22,505

37.1

31.42

0.10

27

21

38

<0.001

19,542
18,657

32.2
30.7

32.82
35.14

0.11
0.11

29
31

21
22

40
45

14,74330,17910,520
5,262

24.3
49.7
17.3
8.7

34.72
32.90
32.61
29.77

0.12
0.09
0.14
0.20

31
29
29
26

21
21
22
20

44
41
40
36

<0.001

2,924
57,786

4.8
95.2

46.80
32.32

0.27
0.06

46
28

32
21

32
39

<0.001

1,385
2,322
5,041
858
3,860
2,439
7,817
536
1,816
20,204
9,171
4,386

2.3
3.8
8.3
1.4
6.4
4.0
12.9
0.9
3.0
33.3
15.1
7.2

32.80
34.53
34.84
33.39
35.98
36.39
35.30
34.89
34.51
33.24
29.43
27.97

0.39
0.30
0.21
0.50
0.23
0.29
0.16
0.63
0.34
0.10
0.15
0.22

28
31
31
30
32
33
32
32
30
29
25
24

21
22
22
21
23
24
23
23
22
21
19
19

40
43
44
43
45
46
44
43
44
41
35
33

<0.001

869

1.4

29.00

0.49

24

19

34

Post hoc
p-valuea

Reference<0.001<0.001
Reference<0.001<0.001<0.001th

Note : 25 and 75 = 25 and 75 percentiles ; PCL-S = Posttraumatic Stress Disorder Checklist-Stressor Specific
Version. aDunnett’s procedure was used for all analyses. bRestricted residential areas of Date City, as designated by the government

creased with increased numbers in trauma- exposure, displacement, and socioeconomic stressors.
Each additional trauma-exposure stressor was associated with a 1.52 increase in the PCL-S score adjusted for age and sex. On the other hand, thenumber of displacement stressors and socioeconomic stressors were associated with increases in the
PCL-S score by factors of 2.20 and 3.77, respectively.
The interaction between these three stressors was
significant (p value was 0.049).
Categorical analysis
Table 5 presents the adjusted odds ratios (ORs)and 95% CIs for the prevalence of provable PTSD
(PCL-S ≥50) according to socioeconomic status anddisaster-related variables. Psychological distress,
unemployment, changing jobs, decreased income,house damage (total collapse), tsunami experience,nuclear power plant accident experience, and loss of
someone close due to the disaster were associatedwith the prevalence of provable PTSD. Furthermore, the age - and sex - adjusted ORs (95% CIs)
were 8.28 (7.94-8.63), 1.62 (1.54-1.69), 1.14 (1.031.27), 1.44 (1.34-1.48), 11.16 (8.28-15.04) (total collapse versus no damage), 1.73 (1.66 - 1.81), 2.10
(2.00-2.19), and 1.86 (1.77-1.94), respectively. After further adjusting for socioeconomic status anddisaster - related variables, the ORs decreased.
However, the significant associations remained, except for job changes.

PTSD and related factors after a disaster
Table 3.

77

Socioeconomic and Disaster-Related Variables with PTSD Severity.
Total
Number

PCL-S
ANCOVAp-value

Post hoc
p-valuea

36
39
42<0.001

Reference
0.758<0.001

23
20

44
36

<0.001

31
32

22
23

45
44

<0.001

0.13
0.07

33
22

24
43

46
9

<0.001

34.17
32.97

0.30
0.06

29
32

22
23

40
45

<0.001

2.4
97.6

32.20
33.03

0.53
0.06

27
32

20
23

39
44

0.008

36.1
63.9

35.52
32.43

0.14
0.07

32
28

23
21

44
40

<0.001

80.6
19.4

32.40
35.56

0.07
0.14

28
31

21
23

40
44

<0.001

28.1
56.1
7.5
2.8
5.5

29.71
33.21
37.17
39.37
37.38

0.12
0.08
0.22
0.36
0.26

25
29
34
36
34

20
21
24
25
23

35
41
47
51
48

<0.001

Reference<0.001<0.001<0.001<0.001

1.1
11.5
41.1
4.5
37.6
4.2

35.53
34.79
34.44
33.94
29.13
33.64

0.62
0.19
0.10
0.30
0.11
0.32

33
31
30
30
25
29

22
23
22
22
19
21

48
44
42
42
35
41.5

<0.001

Reference
0.26960.00110.0250<.00010.0006

20.3
79.7

37.14
31.97

0.13
0.07

34
28

24
21

47
39

<0.001

52.7
47.3

36.02
29.66

0.08
0.09

33
25

23
20

46
35

<0.001

19.8
80.2

36.02
29.66

0.08
0.09

35
27

25
21

49
39

<0.001

Median 25th 75th

%

Mean

SD

34.1
8.1
57.9

29.97
32.26
33.78

0.11
0.23
0.08

26
29
30

20
21
22

55.5
44.5

35.50
29.41

0.08
0.09

32
25

3.4
96.6

35.93
32.96

0.45
0.06

40.4
59.6

36.87
31.98

8.0
92.0

Socioeconomic Variables
Type of work
16,042Full-timePart-time
3,810
27,225
Unemployedb
Changed work situation
Yes
31,987
No
25,681
Started a new job
Yes
1,083
No
30,904
Became unemployedYes
12,917
No
19,070Changed jobs
Yes
2,548
No
29,439
Income has increased
Yes
761
No
31,226
Income has decreased
Yes
11,560No
20,427
Disaster-Related Variables
Living place
Inside Fukushima Prefecture
48,902
Outside Fukushima Prefecture
11,802
House damageNo
16,035
Partial damage
31,977
Partial collapse
4,296Partial but extensive collapse
1,593
Total collapse
3,104
Living arrangement at survey
Evacuation shelter539
Temporary housing
5,580
Rental housing/apartment
20,015
Relative’s home
2,207
Own home
18,289
Other
2,061
Experience of tsunami
Yes
12,306
No
48,398Experience of nuclear power plant accident c
Yes
32,006
No
28,698Loss of someone close because of the disasterYes
11,813
No
47,863Note : 25th and 75th = 25th and 75th percentiles ; PCL-S = Posttraumatic Stress Disorder Checklist-Stressor Specific Version. aDunnett’s procedure was used for all analyses. bIncludes students and full-time homemakers. cDefined
as having heard an explosion caused by the nuclear accident.

T. Shiga et al.

78
Table 4.

Estimated Parameters and 95% Confidence Intervals of PCL-S Scores on the Regression Analysis.

Sex

Women 0 ; Men ; 1

Age

Years

Psychiatric history
Education level

No, 0 ; Yes, 1Less than 10 years, 1 ; 10-12 years,
2 ; 13- 15 years, 3 ; more than 15
years ; 4
Outside Fukushima, 0 ; Inside Fukushima, 1

Living place
Mental-health status (K6)

Score (0-24)

Number of trauma exposure
Number (0-3)
stressors
Number of displacement
Number (0-2)
stressors-

Number of socioeconomic
stressors

Number (0-2)

Adjusted for age and sex

Multivariate adjustedc

EPEP

95% CI

95% CI−3.43a

−3.66

−3.20

−1.35

−1.52

−1.86

b

14.24
−0.82

0.10
13.71
−0.96

0.11
14.77
−0.68

0.10
4.29
−0.63

0.09
3.91
−0.73

0.10
4.68
−0.53

−3.09

−3.58

−3.11

−1.23

−1.44

−1.02

1.81
1.52

1.79
1.43

1.82
1.62

1.74
0.84

1.72
0.77

1.75
0.91

2.20

1.81

2.59

0.59

0.32

0.86

3.77

3.57

3.97

1.29

1.15

1.43

0.10

Note : PCL-S = Posttraumatic Stress Disorder Checklist-Stressor Specific Version ; EP = Estimated parameter ; SD
= Standard deviation ; CI = Confidence interval. R2 of the multivariable regression analysis was 0.529.
a
Age was adjusted. bSex was adjusted. cFurther adjusted for psychiatric history, education, living place, mentalhealth status, trauma-exposure stressors, displacement stressors, and socioeconomic stressors.

Discussion
This study aimed to document the restricted
area residents’ levels of PTSD symptoms and therelationships between these symptoms and demographic characteristics, socioeconomic status, anddisaster-related variables. Participants were residents over 15 years of age who lived in the restricted area of Fukushima Prefecture. Among the evacuees in the study sample, 9,037 (14.1%) had severe
PTSD symptoms (PCL-S ≥50) eighteen months after the earthquake. Previous reports have indicated that the prevalence of PTSD per year in Japan
was approximately 0.4%18). Thus, a disproportionately large number of residents in the restricted area
appeared to have experienced symptoms of PTSD
following the disaster. As for demographic information, women, older adults, those with lower academic achievement, and those with a history ofmental illness tended to have higher PTSD scores.
In particular, participants who had a history of mental illness reported severe PTSD symptoms. Regarding the disaster-related stressors, people who
experienced either the tsunami or nuclear power
plant disaster, who lost family members or relatives,or who had serious house damage had higher PCL-S
scores and had the risk of provable PTSD. Additionally, those who had to evacuate from Fukushima
Prefecture or had to evacuate their houses for accommodations at a shelter or temporary housing

showed severe PTSD symptoms. Regression analyses revealed that a greater quantum of exposure todisaster factors and socioeconomic status also contributed to significantly predicting PTSD. Thesefindings have important implications regarding mental-health concerns that warrant special attention inorder to support evacuees after large-scale disasters.
Many surveys have reported that PTSD is often
observed after earthquake disasters19,20). After the
1995 Hanshin - Awaji Great Earthquake in Japan,
many survivors exhibited PTSD symptoms21,22). Ina survey conducted sixteen months after the earthquake, the prevalence of PTSD among office workers in the disaster area was 3.1%, while 10.1% of theworkers were not diagnosed with PTSD but had
some PTSD symptoms23). Another survey of 128
victims in the Hanshi-Awaji area (62 men and 66
women ; mean age, 32.1 years old) 3-4 months after
the earthquake revealed that the prevalence of
PTSD was 12.90% for men, 9.09% for women, and10.94% for the total sample24). Although comparing
the present study with these previous studies is difficult because of differences in the subjects and survey methods, a higher proportion of subjects in thepresent study appear to have PTSD symptoms, evenafter taking age into account.
Earthquake-induced tsunamis can also cause
further damage to surrounding coastal areas25). An
epidemiological study, conducted among 1,294 work-

PTSD and related factors after a disaster

79

Table 5. Odds ratios (OR) and 95% CIs for prevalence of provable PTSD among evacuees on modified Poisson regression analyses.
Age- and sex-adjusted
OR (95% CI)

Multivariate adjusted
OR (95% CI) a
1.00 (reference)Sex

Men (reference)
Women

1.00 (reference)
1.96 (1.80-2.13)Age

15 44 (reference)
45-54

1.00 (reference)

55-64

1.37 (1.10-1.69)

65-74
≥75
Outside Fukushima (reference)
Inside Fukushima

1.52 (1.14-2.02)
1.68 (1.18-2.40)
1.00 (reference)
0.73 (0.69-0.76)

Psychological distress (K6 ≥13)

No (reference)Yes

1.00 (reference)
8.28 (7.94-8.63)

Became unemployed

No (reference)Yes

1.00 (reference)
1.62 (1.54-1.69)

No (reference)Yes

1.00 (reference)
1.14 (1.03-1.27)

Income has decreased

No (reference)Yes

1.00 (reference)
1.44 (1.34-1.48)

House damage

No (reference)

1.00 (reference)
2.62 (2.33-2.96)

Living place

Changed jobs-

Partial damage
Partial collapse
Partial but extensive collapse

1.23 (1.07-1.42)

4.25 (3.56 5.09)-

Total collapse

6.89 (5.43-8.75)
11.16 (8.28-15.04)

No (reference)Yes

1.00 (reference)
1.73 (1.66-1.81)

Experience of nuclear power plant No (reference)
accident
Yes

1.00 (reference)
2.10 (2.00-2.19)

Loss of someone close because of
the disaster1.00 (reference)
1.86 (1.77-1.94)

Experience of tsunami

No (reference)Yes

1.46 (1.33-1.60)
1.00 (reference)
1.10 (0.94-1.28)
1.15 (0.92-1.44)
1.21 (0.89-1.63)
1.27 (0.87-1.85)
1.00 (reference)
0.89 (0.85-0.94)
1.00 (reference)
7.11 (6.81-7.44)
1.00 (reference)
1.17 (1.11-1.23)
1.00 (reference)
1.02 (0.91-1.15)
1.00 (reference)
1.16 (1.10-1.22)
1.00 (reference)
1.75 (1.55-1.97)
2.31 (1.93-2.77)
3.05 (2.40-3.89)
4.04 (2.99-5.46)
1.00 (reference)
1.21 (1.15-1.27)
1.00 (reference)
1.45 (1.38-1.52)
1.00 (reference)
1.25 (1.19-1.31)

aAdjusted for age, sex, living place, psychological distress, becoming unemployed, decreased income, house damage, experiencing the nuclear power plant accident, and loss of someone close.

ers (local municipality workers, n = 610 ; hospital
medical workers, n = 357 ; firefighters, n = 327) incoastal areas of Miyagi Prefecture14 months after
the Great East Japan Earthquake, found that theprevalence of probable PTSD among local municipality workers, hospital medical workers, and firefighters was 6.6%, 6.6%, and 1.6%, respectively26). According to that study, an increased risk of PTSD was
associated with lack of rest in the municipal andmedical workers, lack of communication with medical workers, and municipal workers’ involvement indisaster- related work. These findings elucidate
the importance of socioeconomic stressors as a risk
factor of PTSD. Since most studies on PTSD after
the Great East Japan Earthquake have focused on
medical staff and workers27), making simple comparisons with the results of the current study is difficult.

However, a review reported that a higher proportionof residents and workers in the affected areas of Fukushima Prefecture had PTSD symptoms than in
any of the previous studies, suggesting that the nuclear power plant accident may have had some effect27).
After the nuclear power plant meltdown in
Chernobyl, people near the accident site presented
with long-term mental-health problems, including
PTSD28). Bromet, Havenaar, and Guey5) reported
that technological disasters predict PTSD in approximately 15% to 75% of the survivors, depending on
the gravity, severity, and level of threat from the disaster, the risk population, and the timing of thestudy. In the present survey, people who had experienced a nuclear disaster showed severe PTSD
symptoms, and those evacuated due to the accident

80

T. Shiga et al.

experienced further deterioration of their symptoms.
Two meta-analyses by Brewin, Andrews, andValentine29) and Ozer, Best, Lipsey, and Weiss30) wereconducted to investigate the psychosocial risk factors of PTSD. Both studies found evidence thatboth trauma-related and post-trauma related factors,
including socioeconomic factors, predicted PTSD.
As noted, our results are consistent with Brewin’s
meta-analysis, showing that women, older and lesseducated people, and people with a psychiatric history exhibited more severe PTSD symptoms. A history of mental illness was a strong predictor of
PTSD symptoms after the disaster. In Brewin’s
meta-analysis, trauma severity, lack of social support, and additional life stressors were somewhat
better predictors of PTSD than pre-trauma factors.
Consistent with this finding, our regression analyses
showed that socioeconomic stressors tended to havehigher estimated parameters on the PCL-S scoresthan disaster-related factors. Moreover, we could
find significant interaction between these stressors,which indicates that these stressors interact for afurther impact on PTSD. This study implied that it
may be important to give refugees appropriate housing support or employment support as well as medical support for PTSD. We should intensively support those who have several traumatic events,
women, older people, or those who have psychiatrichistory. We also need to research what types of living environments or employment arrangements weshould provide for victims. Our regression analysis
revealed that residence after the evacuations also affected the evacuees’ symptoms, even in the multivariate adjusted model. Compared to the people
living in Fukushima Prefecture, those living outsideof it might not have received sufficient social support during the evacuation 31,32). Moreover, theymight have felt more anxious about radiation thanthose living in Fukushima, and therefore, might havedecided to leave Fukushima. Further studies ofperception of radiation risk should be conducted in
the future. Although both of these meta-analyses
show that previous trauma is an important risk factor for PTSD, this item was not included in ourquestionnaire, which is one limitation of our study.
PTSD is an anxiety problem that develops after
extremely traumatic experiences, such as combat,
crime, an accident, or natural disaster. This study
showed that the nuclear power plant accident could
also induce PTSD. The present study found that
the PCL-S scores were significantly higher in Futaba Town, followed by Okuma, Namie, and Katsurao.

These municipalities are located near the Fukushima
Daiichi Nuclear Power Plant. This finding appears
to be characteristic of Fukushima Prefecture after
the nuclear accident because invisible and inaudible“information” about radioactive contamination may
cause PTSD symptoms, in addition to real life experiences. In the case of Fukushima, the serious nature of the negative information brought on the
stressors, which were fears of radiation exposure, or“radiophobia.” The perception of radiation risk inFukushima increased the psychological distressamong evacuees13). Those who lived near the nuclear power plant might have had more PTSD symptoms or a longer delay in recovery due to the perceived stigma associated with radiation, theirwounded pride among fellow residents within theirhometowns, or their inability to gain a long-term
perspective. Media coverage of disasters probably
affected the public’s perceptions by increasing fear
and anxiety33).
There are several strengths and limitations inthis study. The strengths are that the sample sizeis large and the participants were drawn from theentire population of evacuees. Although this is across-sectional study, the presumption of causality
is strong. As for the limitations, because the response rate was relatively low and the response ratevaried according to sex and age groups, it is not clearthat the respondents to the survey represented the
population. However, when we further analyzed
the associations of PCL scores with socioeconomic
factors and disaster-related variables stratified by
sex and age, the associations were essentially same
regardless of sex and age. Furthermore, interviews
have been used to compare the differences in subject characteristics between respondents and nonrespondents34). Thus, nonrespondents had a significantly higher proportion of psychological distresscompared with the respondents. Therefore, thecurrent study may have underestimated the proportion of individuals with PTSD. The other limitationis that PTSD symptoms were evaluated based on
the individual questionnaires ; they were not basedon interviews from experts.
In conclusion, this study revealed that, in addition to the earthquake and tsunami, the nuclear disaster and its consequent changes to evacuees’ living ar rangements might have increased theincidence of PTSD symptoms. In addition to PTSD
risk, which has been found in previous studies, people’s fear of radiation exposure and the need to coordinate improvements in social services are important areas of focus for mental - health support

PTSD and related factors after a disaster

professionals in Fukushima. In the future, observing trends in PTSD symptoms and examining factorsthat contribute to their improvement to maintain themental health of residents in the evacuation zone of
Fukushima Prefecture will be important.

Acknowledgments
The findings and conclusions of this article aresolely the responsibility of the authors and do not
represent the official views of the Fukushima Prefecture government. This survey was supportedby the National Health Fund for Children and Adults
Affected by the Nuclear Incident.
We express our deepest gratitude for the workof expert committee members, advisors, and staff ofthe Mental Health and Lifestyle Survey of the Fukushima Health Management Survey.

Sources of support
This survey was supported by the National
Health Fund for Children and Adults Affected by the
Nuclear Incident.

Conflicts of interests

7.

8.

9.

10.

11.

12.

13.

We declare that we have no competing interests.

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