Department of Psychiatry, Washington University School of Medicine, St Louis, Missouri
Department of Psychiatry and Behavioral Sciences, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
US Department of State, Office of Medical Services, Washington, DC, and Duke University School of Medicine, Department of Psychiatry and Behavioral Science, Durham, North Carolina
Department of State, Office of Medical Services, Washington, DC
Washington University School of Medicine, Department of Psychiatry, St Louis, Missouri
George Warren Brown School of Social Work, Washington University, St Louis, Missouri
Department of Mathematics and Division of Biostatistics, Washington University, St Louis, Missouri, USA
Correspondence: Dr Carol S. North, Department of Psychiatry, Washington University School of Medicine, 660 S. Euclid Avenue, Campus Box 8134, St Louis, Missouri 63110, USA. Tel: +1 314 747 2013; fax: +1 314 747 2140; e-mail: NorthC{at}psychiatry.wustl.edu
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ABSTRACT |
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Aims To compare systematically assessed mental health in populations directly exposed to terrorist bombing attacks on two continents, North America and Africa.
Method Structured diagnostic interviews compared citizens exposed to bombings of the US Embassy in Nairobi, Kenya (n=227) and the Oklahoma City Federal Building (n=182).
Results Prevalence rates of post-traumatic stress disorder (PTSD) and major depression were similar after the bombings. No incident (new since the bombing) alcohol use disorders were observed in either site. Symptom group C was strongly associated with PTSD in both sites. The Nairobi group relied more on religious support and the Oklahoma City group used more medical treatment, drugs and alcohol.
Conclusions Post-disaster psychopathology had many similarities in the two cultures; however, coping responses and treatment were quite different. The findings suggest potential for international generalisability of post-disaster psychopathology, but confirmatory studies are needed.
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INTRODUCTION |
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METHOD |
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Oklahoma City
The Oklahoma City bombing was the most severe act of terrorism experienced
on American soil at the time. The research methods and findings are described
in detail in another publication (North
et al, 1999). Briefly, 182 survivors were randomly
selected from the Oklahoma Health Department's registry of more than 1000
directly exposed individuals and interviewed with the DIS/DS an average of 6
months after the bombing. Diagnosis rates described here vary slightly (2%
lower for post-traumatic stress disorder and major depression) from those
previously published, because of adjustment to DSM-IV criteria
(American Psychiatric Association,
1994; North et al,
1999).
Nairobi
Eight to ten months after the bombing, 227 Kenyan civilians directly
exposed to the bomb blast were assessed with the DIS/DS. The Nairobi bombing
sample was drawn from six major businesses in the immediate vicinity of the
embassy, all of which had sustained substantial physical damage. Every fifth
individual present at the bombing was selected from rosters of employees of
the participating businesses, yielding a list of 271 potential participants.
Interviewers contacted individuals from the rosters, 44 of whom refused or
were unavailable for interview, yielding 227 participants (84% participation
rate). Study participants were interviewed privately at their workplace or in
their home, according to the participant's preference. Those interviewed
received 200 Kenyan shillings for participating, valued at about US$3 and
considered to be equivalent in value to payments provided to research
participants in the USA. Participants were informed that a Federal certificate
of confidentiality had been obtained for protection of their privacy, and all
provided written informed consent prior to participation.
Selected sections (post-traumatic stress disorder, major depression, panic disorder, generalised anxiety disorder, somatisation disorder and alcohol use disorder) of the Diagnostic Interview Schedule for DSM-IV, with adjustments for cultural fit, were used. Previous work has concluded that, with appropriate modifications, existing measures and American conceptualisations of post-traumatic stress disorder (PTSD) and other psychopathology can be applied to African populations (Bolton, 2001; Carey et al, 2003; Dinan et al, 2004). Diagnostic Interview Schedule diagnoses allowed specification of lifetime occurrence and current, pre-disaster and post-disaster prevalence. Retrospectively made pre-disaster diagnoses allowed specification of post- disaster disorders as new (incident) or persistent/recurrent disorders pre-dating the bombing.
The Disaster Supplement provided information about exposure to the disaster, subjective perceptions, functional status, coping methods and treatment, and was administered through interview and self-report questionnaire formats. All assessments were conducted in English, one of two official Kenyan languages.
To maximise the study's cultural interface, eight Nairobi mental health professionals conducted the interviews after completing the research team's formal interview training. Adjustment of the study instruments for cultural acceptability was accomplished during training, soliciting question-by-question input for culturally appropriate and optimal comprehensibility. This usually involved alterations of single words or phrases to replace American idioms with familiar wording for Kenyans: for example, the word blue to describe mood was considered to be culturally inconsistent, and empty was substituted as a best approximation. All interviewers were observed in live interviews until they achieved competency. Interview materials were systematically edited for accuracy and reviewed with the interviewers to answer questions and ensure procedural consistency of the interviewing.
Data preparation and analysis
Data were entered into Excel spreadsheets by personnel in Nairobi and
systematically compared with the interviews for consistency. In St Louis, the
data were transformed into SAS files for analysis
(SAS, 2000). Diagnoses were
scored using DSM-IV criteria (American
Psychiatric Association, 1994). Nairobi and Oklahoma City data
were merged in SAS.
For this report, data are summarised as means with standard deviations and
as percentages. Variables are compared in the Nairobi and Oklahoma City
post-bombing data-sets. Comparisons of categorical variables between the two
sites were accomplished with chi-squared analyses (substituting Fisher's exact
tests when expected cell numbers were less than 5), and numerical variables
with Student's t-tests. To compare rates of the same diagnoses before
and after the disaster, McNemar's test was used. Multiple logistic regression
models were developed to predict PTSD after the bombings from various
independent variables simultaneously. Statistical significance was set at
=0.05.
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RESULTS |
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Exposure to the bombing and perceptions of the event
The injury rate in Oklahoma City was 87% and in Nairobi it was 88%,
lacerations being most common (Table
2). In Nairobi rates of smoke inhalation injuries were double and
ocular injuries were treble those in Oklahoma City, and hospitalisation and
surgery rates were more than twice as high in Nairobi. More Nairobi than
Oklahoma City participants said they recalled thinking they were going to die
during the bombing, had witnessed death or injury in the bombing, acknowledged
death of a family member or friend in the bombing, reported very high
subjective upset associated with the bombing, and described the bombing as the
worst event they had ever experienced in their lives.
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Post-disaster functioning, social support, coping and treatment
Post-traumatic functional impairment, defined as interference with family,
friends or work, was no different between the Oklahoma City (39%) and Nairobi
samples (40%) (not shown in tables). However, dissatisfaction with performance
of their home chores most of the time in the past month was more often
acknowledged by respondents in Nairobi (64%) than in Oklahoma City (42%;
2=18.97, d.f.=1, P<0.001).
More respondents in Oklahoma City (74%) than in Nairobi (30%) reported
getting along well with their spouses (2=51.66, d.f.=1,
P<0.001). However, the proportions reporting a negative change in
their marital relationship after the bombing did not differ by site (average
19%). Frequent attendance at religious services (i.e. more than weekly) was
more often acknowledged in Nairobi (46%) than in Oklahoma City (15%;
2=42.80, d.f.=1, P<0.001), and by more Nairobi
women (50%) than men (36%;
2=4.22, d.f.=1, P=0.04).
Increased attendance at regligious services after the bombing was reported
more often in Nairobi (33%) than in Oklahoma City (10%;
2=30.02, d.f.=1, P<0.001).
Few Nairobi participants reported increased consumption of alcohol or cigarettes after the bombing (Table 3; equivalent data unavailable for Oklahoma City). Fewer participants in Nairobi than in Oklahoma City drank alcohol or took medication to help them cope with the bombing. Turning to family or friends for support, a popular response in both settings, was even more popular in Nairobi than in Oklahoma City. Respondents were asked if anything else helped them cope, and no new category emerged in the Nairobi study.
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Respondents in Nairobi and Oklahoma City used mental health services to a similar extent, although the type of assistance used varied by setting. Psychiatric treatment was exclusive to Oklahoma City, but other mental health treatment was used approximately equally in both settings. Support or debriefing groups and help from religious leaders were more often used in Nairobi.
Psychiatric disorders
Gender differences necessitate the presentation of results separately for
men and women (Table 4). The
DIS onset and recency specifications provided separate pre- and post-bombing
diagnosis rates, allowing separation of incident (new) disorders occurring for
the first time after the bombing from pre-existing psychopathology.
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Pre-disaster
The only difference in rates of pre-existing diagnoses between Nairobi and
Oklahoma City was less alcohol misuse and dependence, found in both men and
women in Nairobi.
Post-disaster
In Nairobi, a third of the men and half of the women had bombing-related
PTSD, and these rates were similar to those in Oklahoma City men and women. In
both Oklahoma City and Nairobi, women's post-bombing rates were higher than
men's for all PTSD (Oklahoma City, 2=5.89, d.f.=1,
P=0.015; Nairobi,
2 5.05, d.f.=1, P=0.025)
and for bombing-related PTSD (Oklahoma City,
2=7.23, d.f.=1,
P=0.007; Nairobi,
2=4.76, d.f.=1, post-bombing
P=0.029). The prevalence of major depression in Nairobi did not
differ by gender, whereas the rate in Oklahoma City men was about double that
in women (
2=9.82, d.f.=1, P=0.002). Nairobi women had
no post-disaster alcohol use disorders, a prevalence significantly less than
in Oklahoma City women after the bombing. No incident (new post-bombing)
alcohol use disorders were observed in either Nairobi or Oklahoma City men or
women. Although no case of somatisation disorder was diagnosed in men or women
before or after the bombing in Nairobi or Oklahoma City, Nairobi men reported
more somatoform symptoms than Oklahoma City men: 1.2 (s.d.=1.9) v.
0.5 (s.d.=1.1); t=3.04, d.f.=160, P=0.003. Oklahoma City and
Nairobi women did not differ in mean number of somatoform symptoms.
Comorbidity occurred in 44% of the bombing-related PTSD cases in Nairobi
and in 67% of cases in Oklahoma City (2=7.28, d.f.=1,
P=0.007). In Oklahoma City, 63% of women with PTSD had comorbid major
depression after the bombing, compared with 40% of women with PTSD in Nairobi
(
2=5.07, d.f.=1, P=0.024). Oklahoma City men with
PTSD had a 47% rate of comorbidity with major depression after the bombing,
compared with 30% of Nairobi men, a non-significant difference. Only 13% of
participants in both cities had another psychiatric disorder after the bombing
in the absence of PTSD.
Besides female gender, another major predictor of bombing-related PTSD
after the disorder in both sites was pre-existing psychiatric disorder. In
Oklahoma City, PTSD was present in 41% of participants with pre-disaster
psychiatric disorder and 26% of those without (2=4.43) d.f.=1,
P=0.035) and in Nairobi, PTSD occurred after the bombing in 60% of
participants with pre-disaster psychiatric disorder and 36% of those without
(
2=9.55). d.f.=1, P=0.002 sustained The number of
injuries sustained in the bombing predicted PTSD in Oklahoma City
(t=2.23, d.f.=1.79 P=0.027) but not in Nairobi. In Oklahoma
City, individuals with PTSD averaged 6.3 (s.d.=4.3) injuries and those without
PTSD reported 4.9 (s.d.=3.7) injuries. Death or injury to a family member or
friend in the bombing (reported by 77% of people with and 61% of those without
PTSD) was associated with PTSD in Oklahoma City (
2=4.64,
d.f.=1, P=0.031) but not in Nairobi. Post-traumatic stress disorder
was not predicted in either site by having thought one would die in the
bombing, witnessing injury and death, or family history of mental illness.
People in Nairobi who attended religious services weekly were less likely
than less frequent attenders to experience post-disaster PTSD (34% v.
50%; 2=5.60, d.f.=1, P=0.018) and major depression
(11% v. 28%;
2=9.02, d.f.=1 P=0.004).
Frequency of church attendance was not associated with PTSD or major
depression in Oklahoma City.
Symptoms of PTSD
Nairobi bombing survivors had significantly more bombing-related symptoms
than the Oklahoma City bombing survivors
(Table 5). The most commonly
reported symptoms were being jumpy or easily startled, intrusive memories,
insomnia and poor concentration, each reported by 75% or more of the two
samples considered. The least prevalent PTSD symptom was psychogenic amnesia
for the bombing, especially in Nairobi. The majority of participants in both
sites met DSM-IV PTSD criteria B and D, but far fewer met criterion C. Of
those with three or more criterion C symptoms, 84% of the Nairobi sample and
86% of the Oklahoma City sample met the full criteria for PTSD.
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DISCUSSION |
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A recent study of an African sample seeking medical treatment (Carey et al, 2003) using a similar diagnostic instrument found higher lifetime rates of PTSD (46% in women and 42% in men) than in the current study, but rates of lifetime non- disaster trauma were higher (94%) than those described in the Nairobi sample. These differences may relate at least in part to differences in the populations studied. A recent African study (Seedat et al, 2004) of adolescent school-children found that approximately 85% of both South African and Kenyan children had exposure to one or more traumatic events, but the rate of PTSD was much higher in South Africans (22%) than in Kenyans (5%), possibly relating to cultural biases of the 20% Black South African sample and the 97% Black Kenyan sample.
Pre-disaster comparisons of the two populations
Similarities and differences in psychiatric effects of the bombings in
Nairobi and Oklahoma City may relate to pre-existing characteristics of the
communities and specifics of the two attacks. Both bombings targeted US
government buildings situated in busy downtown areas on weekday mornings at
the start of the working day. The population of Nairobi (3 million) is larger
than that of the greater Oklahoma City metropolitan area (1 million). An
important difference between these two settings is economic: the World Bank
ranks Kenya among the poorest countries in the world and the USA as the
richest (World Bank, 2002).
Based on reports that mental disorders are associated with economic hardship
(Lynch et al, 2000)
and poverty (Ludermir & Lewis,
2000; World Health
Organization, 2001), a higher prevalence of mental health problems
might be anticipated in the exposed population in Nairobi compared with its
Oklahoma City counterpart. The higher numbers of deaths (213) and injuries
(approximately 5000) sustained in the bombing in Nairobi compared with
Oklahoma City (168 deaths and around 600 injuries) would further predict more
serious psychiatric sequelae in Nairobi compared with Oklahoma City.
Despite their geographical separation by nearly half a world, the Nairobi and Oklahoma City populations and their mental health responses to the experience of bombing were remarkably similar. Many of the demographic and psychiatric characteristics of the Oklahoma City and Nairobi bombing survivors were comparable both before and after the respective disasters. Additionally, both samples reported an 87% injury rate in the bombings. Similarities among the bombing survivor groups are more remarkable considering the disparate economic status of the two countries, and the greater scope and magnitude of the Nairobi bombing compared with the Oklahoma City bombing in terms of reported deaths and injuries, loss of loved ones, perceived threat to life and limb in the bombing, the less organised rescue and recovery effort, and the less sophisticated emergency medical infrastructure in Nairobi.
Post-disaster comparisons of psychopathology
The prevalence and presentation of characteristics of PTSD were remarkably
consistent in the two sites. The sites also demonstrated similarities in
PTSD-related functional impairment and non-PTSD diagnoses (except that alcohol
use disorders were less prevalent in Nairobi). In both sites significant
predictors of PTSD were a pre-disaster history of psychiatric disorder and
female gender, and PTSD was usually comorbid with another disorder. The
majority in both samples met DSM-IV PTSD criteria B and D, but criterion C was
less often endorsed. Nearly 90% of the survivors interviewed in both sites who
met criterion C also met the full diagnostic criteria for PTSD, suggesting the
potential for the use of this group of symptoms as a screening tool to
identify people with a high likelihood of developing PTSD and to direct them
to more intensive psychiatric care. The replication of this finding from the
Oklahoma City bombing study in the Nairobi bombing study suggests the
potential for its international application.
Major depression showed similar consistency between the sites in both men and women, although the gender difference failed to meet statistical significance in Nairobi. General population research has found the prevalence of major depression in Africa comparable to rates elsewhere (Vadher & Ndetei, 1981; Dhadphale et al, 1989), despite contradictory findings of earlier, less systematic studies (Carouthers, 1947). The female predominance of depression, well documented in the USA (Kessler et al, 1995; North et al, 1999), has also been observed in Africa (Abbott & Klein, 1979; Mitchell & Abbott, 1987; Seedat et al, 2004), although not universally (Dhadphale et al, 1983; Hollifield et al, 1994; Carey et al, 2003).
It has been postulated (Mitchell & Abbott, 1987) that women in Africa express mood-related problems in physical terms (somatisation) rather than as depression. The finding that the women in Nairobi had no higher rate of somatisation than women in Oklahoma City does not support this notion, although the higher rate of somatisation in Nairobi men compared with their Oklahoma City counterparts suggests that it might be more characteristic of African men. The equivalent pre-disaster rates of major depression in Oklahoma City and Nairobi women are further evidence against the expression of depressive illness as somatoform symptoms.
Coping and functioning
Although the prevalence and characteristics of psychiatric illness showed
more similarities than differences in the two national samples, the
participants' responses to the bombings revealed important differences.
Treatment by a psychiatrist was not obtained by any Nairobi survivors in this
study; in Oklahoma City, psychiatric treatment was more easily available.
Support and debriefing groups and religious counselling were used by the
majority of Nairobi survivors, but not by survivors in Oklahoma City. It has
been independently noted that people in Kenya respond to trauma through
religious means (Njenga,
2002). Although the majority of people in both sites coped without
alcohol and medication, and most turned to family and friends for support in
both settings, coping with the help of alcohol and medication was more common
in Oklahoma City, and coping through social and religious supports was more
often seen in Nairobi.
Methodological issues
The strengths of this study were its consistent use of the same instrument,
its diagnostic assessment approach with faithful adherence to diagnostic
criteria, and random sampling implemented at both disaster sites. The study
was limited by differences in the timing of the studies relative to the
respective bombings (4-8 months in Oklahoma City and 8-10 months in Nairobi).
Cultural response bias might have played a part in the comparison of Kenya and
Oklahoma City samples. In particular, Africans may be less willing to disclose
psychiatric symptoms compared with Americans.
The study lacked prospective pre-disaster data for measuring change after the bombing. However, pre-disaster data are virtually never available in disaster studies, and identifying uncontaminated but similar comparison groups is fraught with difficulty in disaster research (North & Pfefferbaum, 2002). Advances in research methods may allow future studies to overcome the difficulties encountered in this line of enquiry, enabling them to generate reliable pre-disaster data, comparison data and experimental data to address causal relationships.
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Clinical Implications and Limitations |
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LIMITATIONS
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ACKNOWLEDGMENTS |
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Received for publication February 5, 2004. Revision received October 12, 2004. Accepted for publication October 16, 2004.