Lifetime and Current Prevalence of Specific Psychiatric Disorders Among Vietnam Veterans and Controls B. Kathleen Jordan, PhD; William E. Schlenger, PhD; Richard Hough, John A. Fairbank, PhD; Charles R. Marmar, MD

\s=b\To determine if Vietnam theater veterans were more likely than controls to have a specific psychiatric disorder other than posttraumatic stress disorder, the rates of specific psychiatric disorders were estimated using the Diagnostic Interview Schedule for national samples of veterans who served in Vietnam, other veterans of the Vietnam era, and matched civilian controls. Overall, there were few differences in rates of disorder between theater and other veterans; there were somewhat more differences between theater veterans and civilians. There were striking differences, however, in rates for most disorders, both lifetime and current, between male theater veterans with high levels of exposure to war zone stress and other male veterans or civilians. Female veterans exposed to high levels of war zone stress also had higher rates than other female respondents for several disorders. (Arch Gen Psychiatry. 1991 ;48:207-215)

report presents findings the lifetime Thisprevalence of specific psychiatric disorders defined their

and current among three by military status during the Vietnam groups era (August 5,1964, to May 7,1975): (1) veterans who served in the Vietnam theater of operations (Vietnam or its sur¬ rounding waters or airspace) during the Vietnam era ("the¬ ater veterans"); (2) veterans who served in the military dur¬ ing the time of the Vietnam conflict but who did not serve in on

Accepted for publication May 17,1990.

From the Center for Social Research and Policy Analysis, Research Triangle Institute, Research Triangle Park, NC (Drs Jordan, Schlenger, and Fairbank); Department of Psychiatry, University of California, San Diego, and the Department of Sociology, San Diego (Calif) State University (Dr Hough); the National Opinion Research Center, University of Chicago (III) (Dr Kulka); and the Langley Porter Psychiatric Institute, University of California, San Francisco (Drs Weiss and Marmar). Reprint requests to Center for Social Research and Policy Analysis, Research Triangle Institute, PO Box 12194, Research Triangle Park, NC 27709 (Dr Jordan). the

PhD; Richard A. Kulka, PhD; Daniel Weiss, PhD;

the Vietnam theater ("era veterans"); and (3) individuals who did not serve in the military during the Vietnam era ("civil¬ ians") but who were matched to the Vietnam theater veteran sample on age, sex, race/ethnicity (men only), and occupation

(women only).

The data were collected as part of the congressionally mandated National Vietnam Veterans Readjustment Study (NVVRS), in which national samples of male and female theater veterans, era veterans, and civilians were inter¬ viewed between November 1986 and February 1988. The primary goal of the study was to determine the prevalence of specific psychiatric disorders and other adjustment problems among Vietnam veterans, both at the time of the interview and during the course of their lives. The NVVRS was a multicomponent epidemiologie study, and the results re¬ ported here are from the survey interview component, the National Survey of the Vietnam Generation (NSVG). The SVG veteran sampling frame was different from many pre¬ vious studies of Vietnam veterans in that it was compiled directly from military personnel records. The sample of civil¬ ian counterparts was an age-matched nationally representa¬ tive area probability sample. The NVVRS estimates for the current prevalence of posttraumatic stress disorder (PTSD) were reported previously.1 For men, 15.2% of Vietnam theater veterans, 2.5% of Viet¬ nam era veterans, and 1.2% of civilians were estimated to have PTSD within the 6-month period before the interview. Comparable rates for women were 8.5% for Vietnam theater veterans, 1.1% for Vietnam era veterans, and 0.3% for civil¬ ians. This report presents findings with regard to other psy¬ chiatric disorders assessed in the NSVG. The NVVRS is one of several large-scale epidemiologie studies of psychiatric disorder conducted in the past 15 years that have used the Diagnostic Interview Schedule (DIS).2 This instrument, which can be administered by lay interview¬ ers, supports the formulation of diagnoses consistent with the criteria specified in the third edition of the DSM-III of the

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American Psychiatric Association. The DIS was developed for use in the National Institute of Mental Health's Epidemio¬ logie Catchment Area (ECA) project, which was the first major study to use the instrument. The ECA project devel¬ oped estimates of lifetime and current prevalence of specific psychiatric disorders for community respondents at five sites in the United States.3,4 The DIS has also been used to develop estimates of the prevalence of psychiatric disorder among several special groups that might be hypothesized to be at risk for increased prevalence of psychiatric disorder, such as pris¬ oners and those persons with acquired immunodeficiency syndrome, diabetes, or other health problems. Vietnam vet¬ erans are another group hypothesized to be at increased risk for psychiatric disorder, which is one of the major reasons why the NVVRS was conducted. Two studies conducted before the NVVRS used the DIS to develop estimates of the prevalence rates for specific psychi¬ atric disorders among Vietnam veterans. The first study was the Vietnam Experience Study, conducted by the Centers for Disease Control, Atlanta, Ga,5 in which more than 4000 male theater and era veterans who met specific criteria (eg, en¬ listed rank) and who were selected with the use of military personnel records were interviewed with the use of the DIS. Findings indicated that three current disorders (lifetime

prevalence rates were not reported) were significantly more prevalent among theater veterans than among era veterans in the month before the interview: major depression (4.5% theater vs 2.3% era veterans), generalized anxiety (4.9% theater vs 3.2% era veterans), and alcohol abuse or depen¬

dence (13.7% theater vs 9.2% era veterans). The second study, a special analysis of DIS data from the ECA project, also estimated the rates of psychiatric disorder among Vietnam veterans.6 For these analyses, data were used for all male respondents at the five sites who reported in the survey interview that they had served in the military. Data for 679 Vietnam theater and era veterans were com¬ bined for this analysis. Most prevalence rates for specific psychiatric disorders among these male veterans of the Viet¬ nam era were estimated to be within the range of the preva¬ lence rates among other ECA household respondents at the five sites. Veterans of the Vietnam era did have somewhat higher rates of lifetime and current alcohol abuse and depen¬ dence (30.6% and 11.6%, respectively), lifetime drug abuse and dependence (11.5%), and lifetime antisocial personality disorder (ASPD) (8.0%). Lifetime depression and lifetime and current schizophrenia, however, were the only disorders that had prevalence rates that were statistically different from those among similar-aged male ECA respondents who had not seen military service during the Vietnam era, with the higher rates found among civilians. The NVVRS follows in a long tradition of research on psychiatric disorder among combat veterans. Historically, much of this work has been devoted to the types of problems now classified under the label of PTSD, a syndrome that was previously known under a variety of labels: nostalgia (Civil War), shell shock (World War I), and combat fatigue or combat exhaustion (World War II and Korean War). Glass7 and Archibald and Tuddenham,8 for example, have reported on psychoneurotic casualties among World War II and Kore¬ an War veterans. The study of psychiatric casualties of war has continued into the present not only in the United States but also in other countries. For example, Streimer et al9 and Tennant et al10 have reported on psychiatric problems among Australian combat veterans and repatriated prisoners of war, and Solomon and colleagues11 have studied psychiatric disor¬ der among Israeli soldiers who participated in combat in Lebanon. While much of this work suggests that combat veterans are at increased risk for experiencing psychiatric

problems, few studies have developed samples and case de¬ termination methods that can empirically support conclusions about the prevalence of disorder and the elevation in rates of specific psychiatric disorders among combat veterans. The NVVRS is one of the most comprehensive and repre¬ sentative epidemiologie studies of veterans ever conducted. It differs from most of the pre-Vietnam studies of veterans in that, unlike these early studies, we were able to develop estimates of the rates of the specific psychiatric disorders, consistent with standard nosologie criteria, for the total vet¬ eran population. The NVVRS was able to provide a more comprehensive assessment of the totality of the psychiatric problems of Vietnam veterans than the other studies of Viet¬ nam veterans that preceded it for four important reasons. First, unlike the ECA study, which was conducted in only a few specific sites, the NSVG studied a true nationally repre¬ sentative sample of Vietnam veterans. Analyses of ECA data in which 1-month synthetic prevalence estimates of specific psychiatric disorders for the total US population were calcu¬ lated indicated that national rates may vary considerably from rates for individual sites.1Z Second, unlike previous stud¬ ies of Vietnam veterans, the NVVRS included all Vietnam veterans—that is, veterans from all services, enlisted and officers, career and one-term soldiers, and men and women. In fact, it is the only study to have developed prevalence estimates of psychiatric disorder among women Vietnam vet¬ erans. Third, it was the only study to include a thorough examination of important subgroup differences in prevalence rates among Vietnam theater veterans—that is, differences by race/ethnicity and levels of exposure to war zone stress. Finally, the NVVRS was the only study to have included matched civilian controls, while also weighting both era vet¬ eran and civilian data to match the demographic characteris¬ tics of theater veterans. SUBJECTS AND METHODS The Sample The NSVG involved in-depth, face-to-face interviews that aver¬ aged 3 to 5 hours. Veteran respondents were selected randomly from the military records of all 8.2 million veterans—men and women, enlisted and officers, and all branches of the military—who served during the Vietnam era. The random selections were done separately for the two groups of veterans: those serving in Vietnam or its surrounding waters or airspace and those serving elsewhere during the period. The civilian counterpart sample was a nationally repre¬ sentative area probability sample. Only those civilians who would have been eligible to serve in Vietnam (based on age and country of residence during the Vietnam era) were part of the sampling frame. The female sample was augmented by a list sample of registered nurses because a high proportion (>80%) of women theater veterans were nurses. After standardization on age and race (see below), 13% of the males in the civilian sample had served on active duty in the military (either before or subsequent to the Vietnam era). A total of 3016 interviews were completed in the NSVG. Informed consent was obtained from respondents before the interview. The response rates were

greater than 83% for Vietnam theater veterans, 76% for Viet¬ veterans, and 70% for civilians.

nam era

Weighting and Standardization We conducted detailed analyses of military record data to identify differences between veteran respondents and nonrespondents. These analyses revealed no important differences. Nonetheless, we weighted data for all analyses to compensate for interview-level nonresponse and for different probabilities of selection. It was also important to control for other differences between theater veterans and controls that might affect the results. To do this, we standardized the era veteran and civilian samples to the theater veteran sample on age; similarly, we standardized male controls to male theater veterans on race/ethnicity and female controls to female theater veterans on occupation. We did this standardization proce-

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by weighting the era and civilian data to match the age, male race/ethnicity, and female occupation distributions of theater veter¬ dure

standardization allowed us to control for any cohort effects prevalence of the specific psychiatric disorders. We standard¬ ized (weighted) the male control groups on race/ethnicity to ensure that any prevalence rate differences between samples were not due to differences in the racial and ethnic composition of the groups. We standardized (weighted) the female groups on occupation because the large majority (about 85%) of women Vietnam theater veterans were nurses, and nurses were likely to differ in important ways, eg, level of education, from their age-matched peers. Similarly, we standardized samples of era veterans and civilians to match the characteristics of theater veterans exposed to high levels of war zone stress when we compared theater veterans exposed to high levels of war zone stress with controls. ans. Such on the

Measurement of Psychiatric Disorder

We assessed the specific psychiatric disorders other than PTSD with data from the DIS, version IIIA. The DIS is a highly structured interview schedule designed to be used by lay interviewers in epide¬ miologie studies.2 We developed diagnoses using DSM-III criteria, and both lifetime and current disorder were assessed. The DIS diagnostic categories included in the NSVG (NSVG/DIS disorders) were major depressive episode, manic episode, dysthymia (lifetime

prevalence only), panic disorder, obsessive-compulsive disorder, generalized anxiety disorder (GAD), alcohol abuse or dependence, drug abuse or dependence, ASPD, any NSVG/DIS disorder (any of the previous nine lifetime or eight current disorders), and any NSVG/DIS disorder, except alcohol abuse and dependence. (We created two summary diagnostic variables because the relatively high rate of alcohol disorder among veterans could obscure differ¬ ences

between groups on an overall summary variable.) The lifetime

prevalence of a particular disorder is the proportion of individuals who ever met the diagnostic criteria for that disorder. The DIS permits assessment of "current disorder" for several different time frames; for the purposes of this study, we defined current prevalence as 6-month prevalence, which the DIS diagnostic algorithm defines as the proportion of individuals who have met the diagnostic criteria at some time in their lives and who have experienced at least one symptom of the disorder in the past 6 months.

Measurement of War Zone Stress For analyses, we created a measure that would (1) represent the relative exposure of respondents to war zone stress and (2) reflect the multidimensionality of the phenomenon of war zone stress expo¬ sure that prior research has demonstrated.13 We used nearly 100 items that prior research has suggested may be elements of war zone stress in a principal component analysis to derive empirically a set of specific measures of the underlying dimensions. We identified four war zone stress dimensions for men (exposure to combat, exposure to abusive violence and related conflicts, deprivation, and loss of mean¬ ing and control) and six war zone stress dimensions for women (exposure to wounded and dead persons, exposure to enemy fire, direct combat involvement, and exposure to abusive violence, depri¬ vation, and loss of meaning and control). These dimensions differed by gender, reflecting the different roles of men and women in the war. After we created indexes for these separate dimensions (for men and for women separately), a second-order principal components analysis indicated that the separate indexes could be combined statistically into one overall index of war zone stress exposure for men and one for women. We defined "high-exposure" and "low- or moderate-expo¬ sure" groups with the use of the overall indexes. When we compared these indexes that were based on self-report of war zone stress exposure with information in the military records (eg, receipt of combat medals), we found that the correspondence between the selfreport and the military records was good.4 our

RESULTS

Military Service and Demographic Characteristics Overall, we found only a few significant differences between male

theater veterans and era veterans in the dozens of characteristics that we examined.14 (For purposes of comparing the characteristics of theater and era veterans, the data were not standardized on age, race/ethnicity, or occupation.) Because female theater veterans were

Table 1 .—Percentages of Theater and Era Veterans With Selected Military Service Characteristics* % (SE) Women

Men Theater

Characteristic Branch(es) of US service

Era

(n 1200) (n 412) =

=

Era

(n = 304)

=

(2.2) (1.1) (2.1) (0.4)

47.5

(6.7)t

23.4

(6.4)i (4.2) (2.2)t

79.0

0.1

(2.0) 47.1 (3.7) (1.7) 22.3 (3.3) (1.5) 25.8 (3.4)§ (1.1) 4.8 (1.7)t (0.1) 0.9 (0.6)

27.2

(1.6) 30.9 (3.5)

0.0

0.0

12.4

(1.3)

0.0

0.0

48.6 11.7

(2.5) 91.0 (1.8)t (2.4) 7.9 (1.7)t (1.6) 1.0 (0.5)t

22.5

(2.1)

Army Navy

54.2

Air Force

16.8

Marine Corps Coast Guard Entry into service Drafted Enlisted to avoid draft Enlisted

10.5

21.8

11.3

(2.3)

56.3 (1.9) 56.1 (3.7) voluntarily Direct commission 0.1 (0.1)

Lifetime and current prevalence of specific psychiatric disorders among Vietnam veterans and controls.

To determine if Vietnam theater veterans were more likely than controls to have a specific psychiatric disorder other than posttraumatic stress disord...
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