Original Investigation | Psychiatry

Association of Postdisaster Depression and Posttraumatic Stress DisorderWith Mortality Among Older Disaster Survivorsof the 2011 Great East Japan Earthquake and Tsunami
Xiaoyu Li, ScD; Jun Aida, PhD; Hiroyuki Hikichi, PhD; Katsunori Kondo, MD, PhD; Ichiro Kawachi, MD, PhD

Abstract

Key Points

IMPORTANCE Depression and posttraumatic stress disorder (PTSD) represent 2 common mental
health sequelae of natural disasters. However, to date, no studies have examined whether
postdisaster depression and PTSD are associated with increased risk of mortality among communitydwelling survivors of natural disasters.

Question Are postdisaster depression
and posttraumatic stress disorderassociated with all-cause mortality
among community-dwelling, older
natural disaster survivors?

OBJECTIVE To assess whether postdisaster depression and PTSD were associated with mortality in

Findings In this cohort study of data

older disaster survivors.

from 2965 individuals, depression was
significantly associated with mortality,

DESIGN, SETTING, AND PARTICIPANTS In this cohort study, prospective data were retrieved from

whereas posttraumatic stress disorderolder Japanese adults in Iwanuma City, Miyagi Prefecture, which was directly affected by the 2011

was not. Comorbid depression andGreat East Japan Earthquake and Tsunami. The baseline was established 7 months before theposttraumatic stress disorder were notdisaster (August 2010), and follow-up surveys were conducted approximately 2.5 years afterward

associated with additional risk of(October 1, 2013, to January 31, 2014). Invitations were mailed to every citizen 65 years or older inmortality compared with

Iwanuma City. Mortality data were obtained through March 4, 2017. Data analysis was performed

depression only.

from December 1, 2018, to June 30, 2019.

Meaning The findings suggest thatEXPOSURES Postdisaster depression (Geriatric Depression Scale Short Form score ⱖ5) and PTSD
(Screening Questionnaire for Disaster Mental Health PTSD subscale score ⱖ4) were measured
in 2013.

disaster recovery and reconstruction
efforts should be directed to theprevention, screening, and treatment of
postdisaster depression.

MAIN OUTCOMES AND MEASURES Mortality data were obtained by linkage to the national longterm care insurance database. Cox proportional hazards regression models were adjusted forpredisaster sociodemographic characteristics, health behaviors, social cohesion, predisaster
depression, and disaster experiences.

+ Supplemental content
Author affiliations and article information arelisted at the end of this article.

RESULTS The response rate for the baseline survey was 59.0% (5058 of 8567 individuals), and thefollow-up rate was 82.1% (3594 of 4380 eligible respondents). A total of 2965 individuals (mean[SD] age, 73.4 [6.2] years; 1621 [54.7%] female) participated in the study. The mean (SD) follow-up
since the 2013 survey was 3.3 (0.5) years. Overall, 974 (32.8%) reported postdisaster depression and
747 (25.2%) reported PTSD. In adjusted models, depression was associated with more than double
the risk of mortality (hazard ratio, 2.29; 95% CI, 1.54-3.42); PTSD was not associated with increased
risk of mortality (hazard ratio, 1.10; 95% CI, 0.73-1.64). When evaluating the association of the
4-category comorbid depression and PTSD variable with mortality, survivors with depression only
(HR, 2.24; 95% CI, 1.43-3.49) as well as those with comorbid depression and PTSD (HR, 2.54; 95% CI,
1.50-4.27) were at increased risk of death during the follow-up period compared with those withneither depression nor PTSD.
(continued)

Open Access. This is an open access article distributed under the terms of the CC-BY License.
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Abstract (continued)

CONCLUSIONS AND RELEVANCE Depression, but not PTSD, was associated with mortality during
3.3 years of follow-up among older disaster survivors. These findings suggest that long-term mental
health consequences of natural disasters may exist and that treating depression in older survivorsof disasters may be beneficial.
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Introduction
Depression and posttraumatic stress disorder (PTSD) are among the most common mental disorders
and confer a heavy burden for individuals, the health care system, and society. The estimated lifetime
prevalence is 16.6% for major depressive disorder and 7.8% for PTSD,1,2 and depression and PTSD
frequently co-occur.2 In addition to the significant mental health burden, studies3-13 also suggest that
depression and PTSD are associated with elevated risk of cardiovascular diseases, diabetes,
functional impairment, lower quality of life, and mortality, mostly in patient, veteran, and general
population samples.
Individuals exposed to natural disasters experience an increased risk of mortality.14 They also
experience an increased risk of depression and PTSD. Empirical evidence suggests thatapproximately one-quarter of disaster survivors have depression and up to one-third develop
PTSD.15,16 Moreover, both disorders tend to persist over time.17 However, despite the abundance ofliterature documenting the prevalence and factors associated with mental health problems after
disaster exposure,16-22 no studies, to our knowledge, have examined whether depression and PTSD
are associated with reduced risk of survival among community-dwelling natural disaster survivors,
particularly among older survivors—the population most likely to develop mental health problems
after disaster exposure.23
We sought to examine the associations among postdisaster depression, PTSD, and all-cause
mortality among older survivors of the 2011 Great East Japan Earthquake and Tsunami during 3.3
years of follow-up. We hypothesized that depression and PTSD would each be associated withmortality and that survivors with comorbid depression and PTSD would be at greatest risk ofmortality. Our data came from a unique Japanese cohort in which information about the mental
health status of community-dwelling residents was available from a baseline survey that predated
the 2011 disaster, thereby reducing the possibility of recall bias.

Methods
Design, Setting, and Participants
The data for this cohort study originated from a larger national population-based cohort, the Japan
Gerontological Evaluation Study (JAGES), which was established in August 2010 (ie, 7 months before
the 2011 earthquake and tsunami) to investigate prospectively the factors associated with disability
onset among community-dwelling Japanese citizens 65 years or older. The protocol for the current
study was reviewed and approved by the human subjects committees of Harvard T.H. Chan School of
Public Health, Tohoku University, Nihon Fukushi University, and Chiba University. Participants
provided written informed consent. All data were deidentified. This study followed theStrengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guideline.
The JAGES cohort represents a collaboration of 10 universities and municipal health authorities
across the nation. In Japan, the municipal health authorities maintain accurate registers of all citizens
in their catchment areas. Using these registers (jyumin-hyou), the JAGES team mailed invitations to
169 215 citizens 65 years or older residing in 31 towns and cities throughout the country. A total of
112 123 citizens responded for a response rate of 66.3%. The baseline survey collected information on

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participants’ sociodemographic characteristics, health behaviors, social interactions, and mental andphysical health status.
Seven months after the baseline survey, the 2011 Great East Japan Earthquake and Tsunami
directly affected 1 of the field sites of the JAGES cohort, Iwanuma City in Miyagi Prefecture, located
80 km to the west of the earthquake epicenter. A total of 187 residents died (of a total population of
44 187), 5428 buildings were damaged, and 48% of the Iwanuma land area was inundated.24 The
research team conducted a follow-up survey among survivors approximately 2.5 years after thedisaster (October 1, 2013, to January 31, 2014). The survey inquired about participants’ experiences
during and after the disaster. Data analysis was performed from December 1, 2018, to June 30, 2019.
Figure 1 summarizes the study recruitment and retention. At baseline, a census was undertakenof every resident of Iwanuma City aged 65 years or older. Mortality data until March 4, 2017 (3.3 years
after the postdisaster survey), were linked to the Iwanuma cohort.

Assessment of Postdisaster Depression and PTSD
Depressive symptoms were assessed with the 15-item Geriatric Depression Scale (GDS), which was
designed specifically for rating depression in older adults25 and translated into Japanese. The GDS
score is based on a linear summation of 15 items (eg, “Are you basically satisfied with your life?”), withhigher scores indicating worse depressive symptoms. Scores of 5 or higher were considered to be a

Figure 1. Sample Flowchart8576 Enrollments in the baseline survey
3518 Nonresponse
5058 Baseline questionnaire survey(August 2010) respondents(response rate 59.0%)
101 Invalid identification or missing
data on sex or age
4957 Valid respondents
577 Lost to follow-up
34 Killed by the disaster
400 Death from other causes
95 Before the disaster
305 After the disaster
92 Moved out
17 Address unknown
34 Too sick to participate
4380 Eligible for the follow-up survey
786 Nonresponse
3594 Follow-up questionnaire survey(October 2013) respondents(follow-up rate 82.1%)
27 Invalid consent
3567 Analytic panel sample
602 Missing information on
postdisaster depression
or PTSD
2965 Analytic panel sample

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PTSD indicates posttraumatic stress disorder.

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positive result for depression.26 The 15-item GDS has demonstrated strong psychometric properties,
with a cutoff point of 5 on the scale having a sensitivity of 92% and a specificity of 81% to detect
major depression as ascertained by the Structured Clinical Interview for the Diagnostic and Statistical
Manual of Mental Disorders, Third Edition.26
All PTSD symptoms were assessed with the 9-item PTSD subscale of the Screening
Questionnaire for Disaster-Related Mental Health (SQD-P), specifically developed and validated forthe older Japanese population after the 1995 Kobe earthquake.23 The SQD-P score is based on thesummation of 9 items (eg, “Do you think about the event when you do not want to?”), with thefollowing predefined categories: slightly affected (score of 0-3), moderately affected (score of 4-5),
and severely affected (score of 6-9). Following the approach described in prior literature,27 wedichotomized the PTSD scores to enable a simpler interpretation in which the moderately andseverely affected (scores of ⱖ4) were considered to be positive for PTSD. The SQD-P has been
psychometrically validated in older Japanese adults affected by disasters and has shown good
validity and reliability. The receiver operating characteristic curve was 0.91 for diagnosing PTSD
against the Clinician Administered PTSD Scale.23
We also created a categorical variable to assess comorbid depression and PTSD. Participants
were divided into 4 mutually exclusive groups: those with neither depression nor PTSD, those withdepression only, those with PTSD only, and those with both depression and PTSD.

Assessment of All-Cause Mortality
The main outcome was all-cause mortality. Mortality data for the participants up to March 4, 2017,
were obtained from the national long-term care insurance database, which gave a mean (SD) of 3.3(0.5) years of follow-up after postdisaster depression and PTSD were measured in 2013.

Covariates
We controlled for predisaster sociodemographic characteristics, health behaviors, social cohesion,
predisaster mental health, and disaster experiences, which have been previously reported to be
associated with postdisaster mental health disorders and survival.16,28-31 Specifically, adjusted
predisaster covariates included age, sex, marital status, household income, education, smoking
status, drinking status, body mass index, social cohesion, and depression (measured by the 15-item
GDS), all of which were measured at baseline in 2010. Disaster experiences were measured in 2013,
which included financial hardship, property damage, health care disruption, and death of close
relatives or friends.

Statistical Analysis
Kaplan-Meier plots and log-rank tests were used to evaluate the cumulative incidence of all-cause
mortality according to the presence or absence of depression and PTSD. The primary analyses used
Cox proportional hazards regression models to examine the associations of postdisaster depression
and PTSD with all-cause mortality. We tested a series of models that sequentially adjusted forpotential confounders. Model 1 included only postdisaster depression and PTSD. Model 2 additionallycontrolled for predisaster covariates, including sociodemographic characteristics, health behaviors,social cohesion, and predisaster depression. Model 3 additionally controlled for disaster experiences.
In addition, we constructed Cox proportional hazards regression models with the 4-category
comorbid depression and PTSD variable (depression only, PTSD only, and both depression and PTSD,
each compared with neither depression nor PTSD), which allowed for a different association
between each category and mortality.
In prespecified supplementary analyses, we further examined the association among
postdisaster depression, PTSD, and mortality by restricting the analytic sample to the 1818
individuals who were free of depression before the disaster (ie, evaluating the risk of mortality
associated with incident depression after the disaster). We also examined models that included
baseline comorbidities (eg, hypertension) and self-rated health. Lastly, we tested for potential effect

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modification by predisaster depression on the associations between postdisaster depression and
PTSD all-cause mortality.
All analyses were performed in R, version 3.5.1 (R Project for Statistical Computing) using thesurvival and the survminer packages. All tests were 2-sided, with a significance level of P < .05. The
data were analyzed from December 1, 2018, to June 30, 2018.

Results
Of 8576 individuals who were invited to participate, 5058 responded, yielding a response rate of
59.0%. The response rate to the follow-up survey conducted after the disaster was 82.1% (3594 of
4380 individuals who were eligible). The analyses were limited to 2965 (mean [SD] age, 73.4 [6.2]years; 1621 [54.7%] female; 2101 [72.8%] married) of these respondents after excluding those who
provided invalid consent (n = 27) and those who provided no information on postdisaster depression
or PTSD in 2013 (n = 602). Descriptive statistics of the analytic sample are presented in Table 1. A
total of 695 individuals (23.6%) experienced financial hardship after the disaster, 1742 (58.8%)
experienced property damage, 319 (10.8%) experienced health care disruption, and 1120 (37.8%)
death of close relatives or friends. In terms of exposures of interest, postdisaster depression was
more prevalent (32.8%) compared with PTSD (25.2%). In total, 225 participants died during 3.3 years
of follow-up. Compared with those who did not provide postdisaster depression and/or PTSD
information or those who were eligible for the follow-up survey but did not respond, the analytic
sample was younger, was more likely to be male, was more likely to be married, had higher householdincome and higher educational attainment, and had lower prevalence of depression before thedisaster (eTable 1 in the Supplement).
The Kaplan-Meier plots in Figure 2 show that mortality rates were significantly higher among
those with postdisaster depression compared with those without (log-rank test: χ 12 = 41.5; P < 001).
Although mortality rates were higher among those with postdisaster PTSD compared with those
without, the difference was not statistically significant (χ 12 = = 1.1; P = .29).
Assumption of proportionality was tested and met. In Cox proportional hazards regression
models, postdisaster depression was significantly associated with mortality (hazard ratio [HR], 2.29;
95% CI, 1.54-3.42) after adjusting for predisaster sociodemographic characteristics, health behaviors,social cohesion, depression, and disaster experiences (Table 2).
After full adjustment, the association between PTSD and mortality was not statisticallysignificant (HR, 1.10; 95% CI, 0.73-1.64). When evaluating the association of the 4-category comorbid
depression and PTSD variable with mortality, survivors with depression only (HR, 2.24; 95% CI,
1.43-3.49) as well as those with comorbid depression and PTSD (HR, 2.54; 95% CI, 1.50-4.27; P = .62
for difference in regression coefficients of the 2 groups) were at increased risk of death during thefollow-up period compared with those with neither depression nor PTSD. Participants with PTSD
only were not at increased risk of death (HR, 1.02; 95% CI, 0.51-2.04).
In supplementary analyses, when restricting the sample to those free of depression before thedisaster, incident depression was significantly associated with mortality (HR, 2.16; 95% CI, 1.29-3.61),
whereas PTSD was not (HR, 1.01; 95% CI, 0.55-1.88) after adjusting for covariates (eTable 2 in the
Supplement). Inclusion of baseline comorbidities and self-rated health as additional covariates did
not change the substantive findings. Moreover, there did not seem to be evidence of effectmodification by baseline depression on the associations of postdisaster depression and PTSD withmortality. The HRs (95% CIs) for all covariates from regression analyses are presented in eTables 3through 5 in the Supplement.

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Table 1. Descriptive Traits of Analytic Samplea
Variables
Predisaster variables
Age, mean (SD), y

Finding (N = 2965)
73.4 (6.2)

Sex
Male

1344 (45.3)

Female1621 (54.7)

Marital status
Unmarried
MarriedHousehold income, mean (SD)b

786 (27.2)
2101 (72.8)
6.8 (3.0)

Education, y<6

41 (1.4)

6-9

940 (32.7)

10-121271 (44.2)≥13622 (21.6)

Smoking status
Current

316 (11.5)

Former780 (28.5)

Never1645 (60.0)

Drinking status
Current

1099 (37.8)

Former103 (3.5)

Never1705 (58.7)

BMI, mean (SD)23.5 (3.1)

Social cohesion, mean (SD)c

3.8 (0.7)

Predisaster depressiondNo

1818 (69.0)

Yes

816 (31.0)

Postdisaster variables
Financial hardshipNo2251 (76.4)

Yes

695 (23.6)

Property damage
Half destroyed or worse

450 (15.4)

Partially destroyed

1292 (44.1)

No damage1187 (40.5)

Health care disruptionNo2646 (89.2)

Yes

319 (10.8)

Loss of close relatives or friendsNo

1845 (62.2)

Yes1120 (37.8)

Depressiond
No

1991 (67.2)

Yes

974 (32.8)

PTSDe
No

2218 (74.8)

Yes

747 (25.2)

Abbreviations: BMI, body mass index (calculated as weight in kilograms divided by square of height in meters); PTSD,
posttraumatic stress disorder.
a

Data are presented as number (percentage) of study participants unless otherwise indicated.

b

Household income was rated on a 15-item scale (1 = less than 0.5 million JPY [equivalent to 4586 USD], 15 = 12 million JPY[equivalent to 110 052 USD] or more).

cSocial cohesion score ranged from 1 (low) to 5 (high).

d

Depression was measured using the Geriatric Depression Scale.

e

Posttraumatic stress disorder was measured using the Screening Questionnaire for Disaster-Related Mental Health.

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Discussion
This study presents the first empirical investigation, to our knowledge, on the associations of
postdisaster depression and PTSD with all-cause mortality among community-dwelling survivors ofa major natural disaster. Data came from a prospective cohort of older survivors of the 2011 Great
East Japan Earthquake and Tsunami. Depression was significantly associated with an elevated risk ofdeath, whereas PTSD was not associated with death during 3.3 years of follow-up. Participants withcomorbid depression and PTSD had no greater risk of death than those with depression only.
Mental disorders might be associated with risk of mortality through biological and behavioral
mechanisms. Postdisaster depression and PTSD trigger a chronic stress reaction in response totrauma. A previous study32 suggested that prolonged stress reactions are associated with impaired
adaption and increased wear and tear on the body. Depression has been linked to a range ofneuroendocrine and inflammatory response alterations (eg, dysregulation of the hypothalamicpituitary-adrenocortical axis and elevated C-reactive protein, interleukin 1, and interleukin 6 levels)in clinical and community samples33,34 that might be associated with increased risk of mortality.
Another pathway by which mental health disorders might be associated with risk of mortality isthrough deleterious health behaviors, such as smoking, binge drinking, physical inactivity, and poor
diet, which are risk factors for mortality.35 Furthermore, not only is emotional distress associatedwith adverse health outcomes, it could also be associated with patients’ prognosis by affecting
medication and treatment adherence and shaping the course of the diseases.36

Figure 2. Cumulative Incidence Curves for Postdisaster Depression, Posttraumatic Stress Disorder (PTSD), and Mortality
A Depression and mortalityB

1.0

Depression and mortality
1.0

+
+

+
0.8

Survival Probability

Survival Probability

0.8

0.6

0.4
StrataNo depression
Depression

0.2
P <.001

0.6

0.4
StrataNo PTSD
PTSD

0.2
P =.29

0

0
0

1

2

3

0

4

1

Time, yNo. at risk
No depression
Depression

1991
974

1970
951

1946
917

2

3

4

2093
695

0
0

Time, y
1908
880

0
0

No. at risk
No PTSD
PTSD

2218
747

2192
729

2148
715

Table 2. Cox Proportional Hazards Regression Models of the Association Between Postdisaster Depression,
PTSD, and Mortality
HR (95% CI)
Risk Factor

Model 1aModel 2bModel 3c

Depression

2.36 (1.80-3.09)d2.22 (1.49-3.30)d2.29 (1.54-3.42)d

PTSD

0.91 (0.67-1.23)

0.99 (0.67-1.45)

1.10 (0.73-1.64)

Abbreviations: HR, hazard ratio; PTSD, posttraumatic stress disorder.
aModel 1 included only postdisaster depression and PTSD.

bModel 2 further controlled for predisaster sociodemographic characteristics, lifestyle covariates, social cohesion, andpredisaster depression.

cModel 3 further controlled for disaster experiences.

d

P < .001.
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Contrary to our hypotheses, we only observed significant associations between depression andmortality but not between PTSD and mortality. There are some possible explanations for the lack ofassociation between PTSD and mortality. First, depression and PTSD have many overlapping
symptoms (eg, sleep disturbances and withdrawal), and the mechanisms by which depression isassociated with risk of mortality might overlap with those by which PTSD is associated with risk ofmortality, making differentiation difficult. Second, it is also possible that the effect size of theassociation between PTSD and mortality was small and that the sample size did not give us enoughpower to detect a significant association. Third, PTSD was assessed approximately 2.5 years after thedisaster. By the time we asked about PTSD, some of the most severely affected individuals might
have already died. Thus, our estimates might be conservative.
The burden of depression and PTSD in this analytic sample of disaster survivors was largely
comparable to that from prior literature, with the sample in our study having a slightly higher
prevalence of depression (32.8% vs 25.8%) and a slightly lower prevalence of PTSD (25.2% vs30.0%-40.0%) than samples in previous review articles.15,16 Only a few studies10,11 have examined
the association among depression, PTSD, and mortality. Our finding that depression, but not PTSD,
was associated with all-cause mortality is consistent with 2 prior studies10,11 that examined theassociations of depression and PTSD with mortality in the context of trauma-exposed populations.
Edmondson et al10 examined a sample of Hurricane Katrina survivors with end-stage renal diseases
recruited from 9 hemodialysis centers in New Orleans, Louisiana, whereas Kinder et al11 evaluated asample of veterans who were primary care patients from 7 Department of Veterans Affairs medical
centers. Both studies10,11 reported that depression, but not PTSD, was associated with elevated riskof death. Our study builds on this line of work by (1) examining the research question in a cohort ofcommunity-dwelling natural disaster survivors, (2) using predisaster depression informationcollected at baseline that reduced the possibility of recall bias, and (3) focusing on older adults, who
are disproportionately affected by disasters. A prior study37 on the Iwanuma cohort reported that
individuals with predisaster depression experienced elevated risk of mortality on the day of thedisaster compared with individuals without depression. Although the mechanism is not clear, severe
depression is often associated with psychomotor retardation in older adults, and it is possible that
individuals with depression were delayed in evacuating from their homes during the approximately
1-hour interval between the initial earthquake and the arrival of the tsunami. Our findings further
showed that persistent postdisaster depression was associated with mortality during 3.3 years offollow-up.
Further etiologic work assessing biological and behavioral explanations for the observed
associations between depression and mortality would be helpful to provide guidance forintervention. Future research might also examine whether successful mental health disorder
treatment has a positive effect on disaster survivors’ well-being.

Limitations
This study has limitations. First, selection bias could be a potential problem because of the 59.0%
baseline response rate and the 82.1% follow-up rate. However, prior research has demonstrated that
the Iwanuma cohort at baseline was demographically representative of the whole older adult
population in Iwanuma City and that those who responded to the follow-up survey did not differ
significantly from those who did not respond.24,38 Although those who did not provide information
on postdisaster depression or PTSD were more likely to have predisaster depression compared withthose who provided information on postdisaster depression or PTSD, the results were likely to bebiased toward the null in this scenario. Moreover, 305 individuals died between the 2011 disaster andthe 2013 survey (Figure 1). These people were likely to be those who were mostly severely affectedby the disaster and might have had a higher prevalence of depression and/or PTSD. Data from thebaseline survey show that among the 305 individuals who died before the follow-up survey, 49.8%
had predisaster depression, whereas 33.5% of the 4380 individuals who were eligible for thefollow-up survey had predisaster depression. Although this finding does not directly show the

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association of the disaster with postdisaster depression and/or PTSD, it is possible that those withpredisaster depression might have had a greater risk of adverse reactions to the disaster. In this case,
we are likely to be underestimating the associations between the mental health disorders andmortality.
The second limitation is that postdisaster depression and PTSD were assessed approximately
2.5 years after the disaster. As a result, only participants with persistent depression and PTSD wereidentified. Future research could evaluate the association of short-term postdisaster depression and
PTSD with mortality. In addition, longitudinal study designs could be used to examine the durationor chronicity of depression and PTSD necessary to induce toxic effects. Furthermore, although the
instrument used to assess PTSD (SDQ-P) appeared to be well aligned with the Clinician Administered
PTSD Scale, with a 0.91 receiver operating characteristic curve. It is likely that it better identifies themore common noncases than the less common cases; thus, it may have failed to identify some true
PTSD cases. The SDQ-P also does not include items that assess impairment, which could be asimportant as symptom endorsement in evaluating whether PTSD is associated with clinicallyimportant outcomes. However, the PTSD screener is efficient and cost-effective in clinical practice,especially in the aftermath of natural disasters. Although it might miss some true PTSD cases, thestudy results indicate that scoring above the threshold on the screener is not associated withincreased mortality risk, which suggests that screening for depression might have more clinical utility
than screening for PTSD symptoms in older disaster survivors. Nonetheless, postdisaster PTSD
screening might be important for identifying adverse outcomes (eg, impairments in work or
relationships and declining physical health) other than mortality. Moreover, cause of death was notavailable in our data set. Future research might consider exploring the associations between
postdisaster mental health disorders and cause-specific mortality.
A third potential limitation is the generalizability of these results from older adults. Future workis warranted to assess whether the findings are generalizable to populations who are younger and/or
populations from other cultures and whether the findings are generalizable to populations exposed
to different types of trauma.

Conclusions
In this study, postdisaster depression, but not PTSD, was associated with all-cause mortality during
3.3 years of follow-up among older disaster survivors of the 2011 Great East Japan Earthquake andTsunami. The findings suggest that in addition to its mental health burden, the presence ofdepression should raise practitioner concerns about its physical health sequelae on disastersurvivors. The high prevalence of depression in the aftermath of natural disasters and their toxic
effects appear to warrant the health care system to allocate appropriate resources for the prevention
and treatment of this type of mental distress. For instance, primary care settings that treat
populations exposed to natural disasters might enhance screening for depression. Physicians might
be more effective if they could recognize and treat the mental disorder early. Furthermore, thefindings suggest that disaster survivors with depression should be monitored for the developmentof adverse health outcomes and be provided with treatment strategies. Disaster recovery andreconstruction efforts directed to the prevention and treatment of postdisaster depression, amodifiable risk factor, might contribute to improved outcomes for disaster survivors.

ARTICLE INFORMATION
Accepted for Publication: October 24, 2019.
Published: December 13, 2019. doi:10.1001/jamanetworkopen.2019.17550
Open Access: This is an open access article distributed under the terms of the CC-BY License. © 2019 Li X et al. JAMA
Network Open.

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Depression, Posttraumatic Stress Disorder, and Mortality Among Older Disaster Survivors

Corresponding Author: Xiaoyu Li, ScD, Department of Social and Behavioral Sciences, Harvard T.H. Chan Schoolof Public Health, 401 Park Dr, Landmark Center 403-S, Boston, MA 02215 (xil288@mail.harvard.edu).
Author Affiliations: Department of Social and Behavioral Sciences, Harvard T.H. Chan School of Public Health,Boston, Massachusetts (Li, Kawachi); Division of Sleep and Circadian Disorders, Department of Medicine, Brigham
and Women’s Hospital, Boston, Massachusetts (Li); Department of International and Community Oral Health,
Tohoku University Graduate School of Dentistry, Sendai, Miyagi Prefecture, Japan (Aida); Division of Community
Medicine and Public Health Practice, School of Public Health, University of Hong Kong, Hong Kong (Hikichi); Center
for Preventive Medical Sciences, Chiba University, Chiba, Japan (Kondo); Center for Gerontology and Social
Science, National Center for Geriatrics and Gerontology, Obu, Japan (Kondo).
Author Contributions: Drs Li and Kawachi had full access to all the data in the study and take responsibility for the
integrity of the data and the accuracy of the data analysis.
Concept and design: Li, Aida, Kawachi.
Acquisition, analysis, or interpretation of data: Li, Hikichi, Kondo, Kawachi.
Drafting of the manuscript: Li.
Critical revision of the manuscript for important intellectual content: All authors.
Statistical analysis: Li.
Obtained funding: Kawachi.
Administrative, technical, or material support: Aida, Kondo.
Supervision: Hikichi, Kawachi.
Conflict of Interest Disclosures: Dr Kondo reported receiving grants from the NEC Corporation and Ryobi
Systems Co Ltd outside the submitted work. No other disclosures were reported.
Funding/Support: This work was supported by grant R01 AG042463 from the National Institutes of Health (DrKawachi); health and labour sciences research grants H22-Choju-Shitei-008, H24-Choju-Wakate-009, H25-ChojuIppan-003, and H28-Choju-Ippan-002 (comprehensive research on aging and health) from the Japanese Ministryof Health, Labour and Welfare; Grants-in-Aid for Scientific Research KAKENHI 23243070, 22390400, 24390469,
and 15H01972 from the Japanese Society for the Promotion of Science; grant S0991035 from the Strategic
Research Foundation Grant-Aided Project for Private Universities from the Japanese Ministry of Education,
Culture, Sports, Science and Technology; and research and development grants for longevity science from theJapan Agency for Medical Research and Development.
Role of the Funder/Sponsor: The funding sources had no role in the design and conduct of the study; collection,
management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; anddecision to submit the manuscript for publication.
Additional Contributions: We thank the Iwanuma Mayor's Office, the staff of the Department of Health andWelfare of the Iwanuma City government, and the other investigators of the study for their valuable support andcontributions.
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SUPPLEMENT.
eTable 1. Comparisons of Predisaster Characteristics: Analytic Sample, Respondents With Missing Postdisaster
Depression/PTSD Information, and Nonrespondents in Follow-up
eTable 2. Cox Proportional Hazards Models of the Association Between Incident Depression, PTSD, and Mortality,
Among the Subsample Free of Depression Before the DisastereTable 3. Cox Proportional Hazards Models of the Association Between Postdisaster Depression, PTSD, andMortality, Full Results
eTable 4. Cox Proportional Hazards Models of the Association Between Comorbid Postdisaster Depression and
PTSD and Mortality, Full Results
eTable 5. Cox Proportional Hazards Models of the Association Between Incident Depression, PTSD, and Mortality
Using, Among the Subsample Free of Depression Before the Disaster, Full Results

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