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Mental Health of Cambodian Refugees 2
Decades After Resettlement in the United States
Grant
N. Marshall, PhD; Terry L. Schell, PhD;
Marc N. Elliott, PhD; S. Megan Berthold,
PhD; Chi-Ah Chun, PhD
JAMA. 2005;294:571-579.
ABSTRACT
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Context Little is known about the long-term
mental health of trauma-exposed refugees years after
permanent resettlement in host countries.
Objective To assess the prevalence, comorbidity, and
correlates of psychiatric disorders in the US Cambodian
refugee community.
Design, Setting, and Participants A cross-sectional,
face-to-face interview conducted in Khmer language on a
random sample of households from the Cambodian community
in Long Beach, Calif, the largest such community in the
United States, between October 2003 and February 2005. A
total of 586 adults aged 35 to 75 years who lived in
Cambodia during the Khmer Rouge reign and immigrated to
the United States prior to 1993 were selected. One
eligible individual was randomly sampled from each household,
with an overall response rate (eligibility screening and
interview) of 87% (n = 490).
Main Outcome Measures Exposure to trauma and
violence before and after immigration (using the Harvard
Trauma Questionnaire and Survey of Exposure to Community
Violence); weighted past-year prevalence rates of
posttraumatic stress disorder (PTSD) and major depression
(using the Composite International Diagnostic Interview
version 2.1); and alcohol use disorder (by the Alcohol
Use Disorders Identification Test).
Results All participants had been exposed to trauma
before immigration. Ninety-nine percent
(n = 483) experienced near-death due to
starvation and 90% (n = 437) had a family
member or friend murdered. Seventy percent (n = 338)
reported exposure to violence after settlement in the
United States. High rates of PTSD (62%, weighted), major
depression (51%, weighted), and low rates of alcohol use
disorder were found (4%, weighted). PTSD and major
depression were highly comorbid in this population
(n = 209; 42%, weighted) and each showed a
strong dose-response relationship with measures of
traumatic exposure. In bivariate analyses, older age, having
poor English-speaking proficiency, unemployment, being
retired or disabled, and living in poverty were also
associated with higher rates of PTSD and major
depression. Following multivariate analyses, premigration
trauma remained associated with PTSD (odds ratio [OR],
2.08; 95% CI, 1.37-3.16) and major depression (OR, 1.56;
95% CI, 1.24-1.97); postmigration trauma with PTSD (OR,
1.65; 95% CI, 1.21-2.26) and major depression (OR, 1.45;
95% CI, 1.12-1.86); and older age with PTSD (OR, 1.76; 95%
CI, 1.46-2.13) and major depression (OR, 1.47; 95% CI,
1.15-1.89).
Conclusion More than 2 decades have passed since the
end of the Cambodian civil war and the subsequent
resettlement of refugees in the United States; however,
this population continues to have high rates of
psychiatric disorders associated with trauma.
INTRODUCTION
Political
instability, civil conflict, war, genocide, persecution,
and the attendant violations of human rights are
increasingly recognized as paramount public health
concerns.1-3
According to the United Nations High Commissioner on
Refugees, there were approximately 19.2 million refugees,
internally displaced persons, and asylum seekers
worldwide in 2004.4
Researchers studying these populations have found high
levels of violence exposure, often involving multiple
traumas, as well as significant mental health
problems.5-10
Empirical investigations generally conclude that
depression and posttraumatic stress disorder (PTSD) constitute
the most common psychiatric disorders in refugee
populations. Inasmuch as depression is a key component of
overall disease burden11
and PTSD is a notable contributor to disease burden,
especially in countries wracked by violence,12
exposure to mass trauma is a significant source of
psychiatric disability worldwide.
Although there is agreement that refugee populations
experience high levels of psychiatric disability, most of
the data for this conclusion come from studies that may
overestimate the magnitude of the problem. Much of this
research has focused on individuals seeking health or
social services who may have more severe problems than
the general population of refugees.6,
13-14Other
studies have assessed individuals petitioning for asylum
who may be motivated to overreport trauma exposure and
related psychiatric symptoms.15-16
Additionally, research is frequently conducted while
refugees are housed in refugee camps or within a short
time after resettlement in a host country.7,
9,
17-19
It is difficult to determine if the psychiatric distress
documented in these studies represents an acute
condition, which might resolve spontaneously or with a
change in circumstances, or whether it reflects a chronic
condition that will persist in the absence of a
therapeutic intervention.
Similarly, there are few published community-based studies
of refugee populations after long-term resettlement in
resource-rich countries like the United States, although
existing research has examined the long-term health
consequences for refugees resettled in resource-poor
countries.20-21
Health outcomes for refugees may vary as a function of
the prosperity of the resettlement country, with persons
resettled in poorer countries experiencing continued
hardships that influence health. Finally, many studies of
refugee mental health have relied on symptom screening
instruments to assess probable diagnoses.6-7,9,
22-23
Although these measures are correlated with clinical
diagnoses and provide useful data, they often fail to
include the necessary information to make diagnostic
assessments. Consequently, they typically err on the side
of high sensitivity rather than high specificity and tend
to overestimate prevalence.24-25
Cambodians constitute one of the largest refugee groups in
the United States, with approximately 150 000
refugees admitted since 1975.26
Although these refugees are now many years removed from
their tribulations, they were subjected to one of the most
brutal and traumatic periods of the past century. After a
coup in 1970, a civil war began that led to a Khmer Rouge
takeover from 1975 to 1979. A Vietnamese invasion in 1979
ended the Khmer Rouge reign, but civil war continued
until United Nations troops enforced a cease-fire in late
1991. Of an estimated population of 7.1 million in
1975,27
as many as 2 million Cambodians were killed during the
4-year Khmer Rouge reign. Approximately 1 million more
were killed in the civil wars before and after this
period.28
The period from 1978 to 1991 also produced more than half
a million refugees in Thailand refugee camps.
The goal of our study was to assess the population
prevalence, comorbidity, and correlates of psychiatric
disorders in the US Cambodian refugee community 25 years
after the Khmer Rouge era, using research methods that
should provide the most accurate available estimates.
This knowledge should provide information concerning the
current health status of this community, guiding
health-policy decision makers to the needed services for
this refugee community.
METHODS
Sample
Design and Participants
Our sample was designed to represent the population of
Cambodian immigrants residing in Long Beach, Calif. This
city is home to the largest single concentration of
Cambodian refugees in the United States. The sample size
was determined by a desire to have relatively small
confidence intervals (±5%) for estimates of prevalence of
psychiatric disorder when the true population prevalence
was 30% or 70%. This level of precision required an
effective sample size of 333. With an expected design
effect of 1.5 due to weights (actual design
effect = 1.47), we aimed to interview 500
individuals.
Specifically, we derived our sample from a geographically
contiguous area composed of the 4 census tracts with the
largest proportion of Cambodians in Long Beach, Calif,
containing approximately 15 000 total households. We
used a 3-stage random sample of individuals within
households within blocks (Figure).
In the first stage, a simple random sample of census
blocks was selected. A community expert then surveyed
blocks with field staff and classified all 5555
households on selected blocks as either likely (18%) or
unlikely (82%) to be Cambodian households. The second
stage consisted of a stratified random sample of
households (n = 2059) in which we oversampled
households judged by the community expert as likely to
contain Cambodian individuals. The community expert
relied on common visual signs, such as plants favored by
the community growing in the lawn or placed on the front
porch (eg, lemon grass, bamboo), and Buddhist or other
icons on the front porch or visible in the window to
select households likely to contain Cambodian individuals.
The likely/unlikely distinction was used to create
sampling strata so that we could then draw random samples
of households from within each of these
subpopulations.
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| Figure. Flow Diagram of Sample
Design and Eligibility Requirements
The unweighted sample of 490 refugees was used
for all analyses; however, a sample size of 482
refugees was realized after weighting.
*Strata membership was determined
by a community expert who judged if the house was
likely to contain a Cambodian based on features
visible from the street (eg, shoes on porch,
Buddhist icons, and Southeast Asian plants).
![{dagger}]() A
household was eligible if it contained at least 1
individual aged 35 to 75 years who had lived in
Cambodia during some portion of the Khmer Rouge
regime (April 1975 to January 1979).
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Selected households were then screened to determine whether
they contained at least 1 eligible individual. Screening
was successfully completed for 2001 (97%) of the sampled
households. Five hundred eighty-six households (29%)
contained 719 eligible Cambodians. In the third stage, a
single eligible individual was selected at random from
each household. Of selected individuals, 527 (90%) agreed
to participate in the survey, resulting in an overall
response rate of 87%. Of these, 37 were not refugees and
were excluded from the analytic sample for this study, yielding
an analytic sample of 490 participants. After weighting
participants to create a sample representative of the
desired population as described below, we had a weighted
sample size of 482.
Individuals were determined to be eligible for interview if
they were aged between 35 and 75 years and had lived in
Cambodia during some portion of the Khmer Rouge regime
(April 1975 to January 1979). In addition, our analyses
were restricted to 490 of those individuals interviewed
who immigrated during the years when the United States
was accepting Cambodian refugees, which effectively ended
in 1992 when the United States adopted policies that
favored repatriating displaced Cambodians. All
participants in our analytic sample left Cambodia prior to
the 1991 cease-fire and the subsequent deployment of a
United Nations peacekeeping force to Cambodia, and all
respondents had spent time in a refugee camp.
Interviewers and Procedures
The interview team was composed of 5 bilingual lay
interviewers. Interviewers were themselves Cambodian
refugees and were required to read, write, and speak
fluently in Khmer and English. Interviewers received
extensive training before conducting interviews and
active supervision throughout data collection. Data were
obtained via face-to-face, fully structured interviews
that took place in participants homes. Interviews were
conducted in Khmer and took approximately 120 minutes to
complete.
Informed Consent Procedures
As part of the informed consent process, potential
participants were told that the purpose of the study was
to learn about the life experiences of people who had
come from Cambodia as refugees and that the researchers
were interested in their current life situation, and
their physical and emotional health. Potential
participants were informed that participation was
completely voluntary and that they were free to stop at
any time. All persons were informed of the specific
topics to be covered in the interview and were expressly
advised that they would be reminded of traumatic
incidents from the past, which may cause them to become
emotionally upset. Potential participants were also
advised that they might wish to talk with someone about
these feelings or concerns and were given contact
information for 2 mental health clinics that provide
services to the Cambodian community. Both clinics were
informed of the existence of the study in advance of data
collection. All informed consent materials were read
verbatim, questions were answered, and written informed
consent was obtained. Following the interview,
participants received a nominal incentive payment and
were reminded that they had the option of availing themselves
of services provided at either of the 2 aforementioned
clinics. Interviewers also reviewed orally with
participants a brochure containing the contact
information for local health, mental health, and social
service agencies, before giving them a copy of the
brochure. The institutional review boards of RAND and the
California State University, Long Beach, approved the protocol.
Translation Procedures
All instruments were translated and back-translated
following recommended procedures to ensure content,
technical, criterion, conceptual, and semantic
equivalence.29
Two bilingual, bicultural Khmer translators translated
all English measures into Khmer. The Khmer version of the
survey was then back-translated into English by a third
bilingual, bicultural Khmer translator to ensure
equivalency and identify discrepancies between the 2
English versions. A small number of discrepancies were
reconciled with the aid of the 3 original translators and
1 additional translator who had not been involved in
either of the initial translations.
Focus Groups and Pretesting
Extensive development work preceded finalization of the
instrument. Focus groups were held with community experts
to identify topics of potential interest and to obtain
feedback on initial versions of the instruments. The
comments of expert advisors were integrated into
successive versions of the interview in iterative fashion.
The instruments were then pretested with multiple
respondents in both English and Khmer to identify areas
of possible confusion.
Instruments
Sociodemographic information, including age, marital status,
education, employment, self-assessed English-speaking
proficiency (not at all, poor, fair, or good), household
size, and household income, was obtained. For analytic
purposes, income was expressed as a proportion of the
federal poverty level. Overseas trauma exposure was
assessed by using a modified version of 17-item Cambodian
Harvard Trauma Questionnaire.30
Additional trauma items were taken from the 46-item
Bosnian version of the Harvard Trauma
Questionnaire.31
The Harvard Trauma Questionnaire is the most widely used
measure of its kind and has been translated into 35
languages.32
In total, respondents were asked whether they had
experienced each of 35 events before immigrating to the
United States. To assess exposure to violence in the United
States, a modified version of the Survey of Exposure to
Community Violence33
was used. Numerous studies document the reliability and
validity of this instrument.34-36
Respondents indicated whether they had witnessed or
directly experienced each of 11 events since arriving in
the United States. For descriptive purposes, the total
number of endorsed trauma exposures is reported for both
premigration and postmigration traumas.
Past 12-month diagnoses of PTSD and major depression were
determined by using the PTSD and depression modules of
the Composite International Diagnostic Interview (CIDI)
version 2.1.37
This instrument is keyed to the Diagnostic and
Statistical Manual of Mental Disorders, Fourth
Edition (DSM-IV)38
criteria. The CIDI is intended to be administered by lay
interviewers and its cross-cultural applicability has
been well established.20,
39-40
The CIDI is designed to assess all criteria required for
a DSM-IV diagnosis, including symptom profiles,
severity, duration, and functional impairment, and, in
the case of PTSD, the required peritraumatic reactions.
Several studies attest to the reliability and validity of
the CIDI.40-43
The Alcohol Use Disorders Identification Test,44
developed as part of an international World Health
Organization collaborative project, was used to screen
for possible alcohol use disorders (AUDs). Perhaps the
most widely used and well-validated alcohol
screener,45
this instrument consists of 10 items. Responses to each
question are scored from 0 to 4, with scores of 7 for
women and 8 for men reflecting a probable AUD.46
Statistical Analysis
Analyses used design weights and corrected for the design
effects of both weighting and clustering.
Inverse-probability design weights accounted for the
underrepresentation of eligible persons in residences
judged unlikely to house Cambodians and for individuals
from households with more than 1 eligible resident.
Nonresponse rates were low and there was no statistically
significant (P<.05) evidence that nonresponse
was associated with variables available for comparison
(census tract, age, and sex). Thus, nonresponse weights
were not constructed. Throughout the text and tables, we
report weighted proportions as percentages and unweighted
sample sizes. All statistical analyses were performed by
using SAS/STAT software version 9.1 (SAS Institute, Cary,
NC).
Proportions and margins of error (computed as half of the
exact binomial 95% confidence intervals) were calculated
for dichotomous variables, whereas means and SDs were
calculated for continuous variables. Bivariate odds
ratios and their 95% confidence intervals were calculated
predicting dichotomous outcomes of major depression,
PTSD, and probable AUD from age and year of immigration
(both of which were scaled as number of years divided by
10, and treated as continuous), sex, the number of
premigration and postmigration trauma types experienced
(expressed as the z score of the sum of each
type), English-speaking proficiency (good/fair vs not at
all/poor), marital status, high school completion, employment
status, and US federal poverty level (below poverty
[<100%] vs above poverty level [ 100%]). Age, sex, year of
immigration, premigration and postmigration trauma
exposure were also included as independent variables in
multivariate logistic regressions predicting the same 3
outcomes.
RESULTS
On average,
participants arrived in the United States in 1983 and
were aged 52 years at interview (Table
1). Sixty-one percent of the respondents were women
and 87% indicated Buddhism as their religious
affiliation. The majority of respondents were married and
low in socioeconomic status, with low levels of
education, English-speaking proficiency, and employment.
Sixty-nine percent of the participants had household
incomes of less than 100% of the federal poverty level
and 72% indicated currently receiving government
assistance.
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| Table 1. Demographic Characteristics
of Participants (N = 490)*
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Participants reported high rates of exposure to trauma and
violence before their arrival to the United States (Table
2). Participants reported experiencing a mean of 15
of 35 premigration trauma types. For example, 99% of
individuals (n = 483) reported near-death due
to starvation, 96% (n = 466) reported forced
labor (like animal or slave), 90% (n = 437)
reported having a family member or friend murdered, and
54% (n = 241) reported having been tortured.
Participants also reported exposure to violence in the
United States, with a mean 1.7 of 11 types of
postmigration trauma exposure. For example, 34% of
individuals (n = 160) reported seeing a dead
body in their neighborhood, 28% (n = 136) reported
having been robbed, and 17% (n = 83) reported
having been threatened by a weapon and believing that
they might be seriously hurt or killed.
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| Table 2. Rates of Trauma Exposure
(N = 490)*
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Consistent with this high level of traumatic exposure, 62%
of respondents (n = 301) met DSM-IV
diagnostic criteria for PTSD in the past year and 51%
(n = 248) met diagnostic criteria for major
depression in the past year (Table
3). Comorbidity between these disorders was high.
Seventy-one percent of persons with PTSD also met
criteria for major depression and 86% of those with major
depression met criteria for PTSD ( = 0.50,
P<.001). In contrast, low levels of probable AUD
were found (4%; n=14). Moreover, AUD was not
significantly associated with either PTSD ( = 0.02,
P = .81) or major depression ( = 0.01, P = .93).
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| Table 3. Past-Year Prevalence and
Comorbidity of Psychiatric Disorders
(N = 490)
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Several demographic variables, in addition to aggregate
premigration and postmigration trauma exposure, showed
bivariate associations with the 3 psychiatric disorders
(Table
4). Specifically, poor English-speaking skills,
unemployment, being in retirement or disabled, and living
in poverty were associated with higher rates of PTSD and
major depression. Older respondents showed higher rates
of PTSD and depression than did younger participants.
However, older respondents had lower rates of probable AUD
than did younger respondents. Women were less likely than
men to have either PTSD or AUD. PTSD and major depression
were both associated with greater exposure to
premigration and postmigration trauma. In contrast, AUD
was significantly associated only with exposure to trauma
after immigration to the United States. The
interpretation of the nonsignificant odds ratio predicting
AUD is limited by the large confidence intervals that
result from the low prevalence of alcohol-related
problems in this sample.
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| Table 4. Bivariate Odds Ratios
Predicting Psychiatric Disorders
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We selected a subset of these variables for further analysis
in multivariate models aimed at predicting each of the 3
outcomes. We focused on constructs that were likely to be
antecedent to the development of the psychiatric
disorders. On this basis, age, sex, year of immigration,
and premigration and postmigration trauma exposure were
selected as potential multivariate predictors. We omitted
several variables included as bivariate predictors due to
concerns about direction of causality.
The odds ratios of these predictors, adjusted for age, sex,
year of immigration, and premigration and postmigration
trauma exposure, show a similar pattern across PTSD and
major depression (Table
5). Participant age and the 2 trauma exposure variables
were positively associated with these psychiatric
disorders. Alcohol use disorder was negatively associated
with age and positively related to extent of trauma
exposure since arriving in the United States. The
bivariate association between sex and psychiatric
disorders was no longer significant after adjusting for
the extent of trauma exposure. Overall, these multivariate
models produced high concordances between actual and
predicted disorder (c statistics of 0.77, 0.71,
and 0.77 for PTSD, major depression, and AUD,
respectively).
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| Table 5. Adjusted Odds Ratios
Predicting Psychiatric Disorders*
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COMMENT
Our study
examined the trauma exposure and mental health of a
stratified random sample of Cambodian refugees residing in
the largest single Cambodian community in the United
States. Although on average more than 2 decades had
elapsed since arriving in the United States, our sample
revealed high rates of past-year PTSD (62%) and
depression (51%). In comparison with epidemiological
studies of the general US population, these rates are
extremely elevated.47-48
At the same time, rates of AUDs in our sample were much
lower than those reported in the general US population.48
The concern that motivated this research is that certain
features of previous studies of refugee samples may
render them likely to overestimate the magnitude of
mental health problems. We found evidence of pronounced
mental health problems in previously traumatized
refugees. Indeed, only approximately 30% of the sample
was free of any of the 3 disorders assessed. These results
indicate that members of refugee communities can have
substantial need for mental health services even years
removed from their tribulations.
These data also demonstrate a dose-response relationship
between trauma exposure (both premigration and
postmigration) and the likelihood of a current
psychiatric disorder. Specifically, degree of exposure to
each broad class of trauma is uniquely associated with
both PTSD and major depression. This finding of a
possible dose-response relationship involving both PTSD
and depression has been found in related refugee
research.8
However, the relationship of trauma to depression has
perhaps not been as widely appreciated. Many refugee
studies focus solely on PTSD to the exclusion of major
depression and other conditions likely to result from
trauma exposure.20,
23
Moreover, in both bivariate and multivariate models,
these findings identify a similar pattern of predictors
for both depression and PTSD. This comparability in risk
factors, along with the high comorbidity between PTSD and
major depression following trauma exposure, raise
questions as to whether PTSD and depression are empirically
differentiable disorders or manifestations of a single
continuum of posttraumatic distress.49
This study found low rates of probable AUD in Cambodian
refugees. Although previous research using convenience
samples has suggested that Cambodian refugees are at high
risk for alcohol abuse,50-51
to our knowledge, this study is the first to assess this
in a representative community sample. These findings are
consistent with other research indicating that
Asian-American subgroups differ substantially in their
drinking patterns, with some groups showing relatively
high abstinence.52
The absence of a relationship between PTSD and alcohol
abuse is particularly striking inasmuch as numerous
studies of US samples report high comorbidity between the
2 disorders,53
with many theorists positing a causal link between PTSD
and alcohol abuse.54
Our findings suggest that researchers looking for
biomedical explanations for the association between
alcohol abuse and PTSD should pay attention to the cultural
context in which drinking occurs, as this factor may
moderate the relationship.
Unlike studies conducted on general US populations, we found
that women were no more likely than men to develop PTSD47
or depression.55
One possible explanation is that the frequency or
severity of the traumas differed for men and women in ways
not captured by ou |