Posttraumatic Stress Disorder in a Community Sample of Former Prisoners of War: A Normative Response to Severe Trauma

Brian Engdahl, Ph.D.1,2, Thomas N. Dikel, M.A.2,3,
Raina Eberly, Ph.D.1,2, and Arthur Blank, Jr., M.D.1,4

Originally published in American Journal of Psychiatry, 1997, 154(11), 1576-1581. Posted at www.trauma-pages.com with the authors' permission. Note that this online version may have minor differences from the published version.
Address reprint requests to Dr. Brian Engdahl, Psychology Service (116B), VA Medical Center, One Veterans Drive, Minneapolis, MN 55417.
From the U.S. Dept. of Veterans Affairs Medical Center1, Minneapolis and Department of Psychology2, the Institute of Child Development3, and Department of Psychiatry4, University of Minnesota.
Supported by research funds from the Department of Veterans Affairs, and the DVA Medical Center, Minneapolis. The authors thank the POW volunteers, Julee Blake, Daniel Sandstrom, and Nicholas Michel for their assistance in this project.
Portions of the data in this article were presented at the International Society for Traumatic Stress Studies Convention, Boston, MA; November 2-6, 1995.

Abstract

Objective: The goal of this study was to assess and describe the long-term impact of traumatic prisoner of war (POW) experiences within the context of posttraumatic psychopathology. Specifically, the authors attempted to investigate the relative degree of normative response represented by posttraumatic stress disorder (PTSD) in comparison to other DSM Axis I disorders often found to be present or comorbid in survivors of trauma.

Method: A community sample of 262 American World War II and Korean War former POWs was recruited. These men had been exposed to the multiple traumas of combat, capture, and imprisonment, yet few had ever sought mental health treatment. They were assessed for psychopathology using diagnostic interviews and psychodiagnostic testing. Regression analyses were used to assess the contributions of age at capture, war trauma, and postwar social support to PTSD and the other diagnosed disorders.

Results: More than half of the sample (54%) met criteria for lifetime PTSD, and 30% met criteria for current PTSD. The most severely traumatized group (POWs held by the Japanese) had lifetime rates of 84% and current rates of 58% for PTSD. Fifty-five percent of those with current PTSD were free from the other current Axis I disorders (uncomplicated PTSD). Also, 34% of those with lifetime PTSD had PTSD as their only lifetime Axis I diagnosis. Regression analyses indicated that age at capture, severity of trauma exposure, and postmilitary social support were moderately predictive of PTSD and only weakly predictive of other disorders.

Conclusions: These findings indicate that PTSD is a persistent, normative, and primary consequence of exposure to severe trauma.

Many studies indicate that a majority of individuals exposed to severe trauma develop posttraumatic stress disorder (PTSD) (e.g., former prisoners of war (POWs; 1-3), torture victims (4), and survivors of war in the former Yugoslavia (5)). In a sample of American POWs a lifetime PTSD rate of 67% was found (1). Among school children exposed to a sniper attack, 58% met criteria for PTSD (6). The National Vietnam Veterans Readjustment Study (NVVRS; 7) found high lifetime PTSD rates among veterans of heavy combat (30%) and among combat-wounded veterans (67%). PTSD rates of 59% to 66% were reported among crime victims exposed to life threat combined with injury (8). The National Comorbidity study (NCS; 9) found lifetime PTSD rates among those exposed to severe trauma ranging from 39% for combat to 65% for rape. Studies in which trauma exposure has been less severe, however, suggest that most subjects exposed to trauma did not develop PTSD (10-12). It further has been proposed that PTSD may represent an abnormal, rather than a normal, response to trauma (13, 14).

Trauma exposure alone does not always lead to PTSD, nor does trauma severity fully predict the likelihood of developing PTSD. Other contributing factors have been identified, including prior trauma exposure (15), a history of childhood conduct problems (7), pre-trauma personality (16), heritability (17), age at trauma exposure (18, 19), and post-traumatic factors such as social support (20) and exposure to re-activating stressors (21). Green, et al. (22) examined the contribution of premilitary, military, and postmilitary risk factors to PTSD and other postwar diagnoses in a sample of Vietnam veterans. Although pre- and postmilitary factors were contributory, PTSD was primarily related to war trauma. Panic disorder was also highly related to war trauma. Prewar functioning played a stronger role in several non-PTSD diagnoses.

Although risk factors other than trauma may affect posttraumatic psychiatric status when trauma is less severe or single-exposure, these other risk factors may decrease in significance as the severity and duration of trauma exposure increase (23). Foy (24) found that, while Vietnam veterans with PTSD generally had the highest rates of family psychopathology, the contribution of family history was nonsignificant for those with high combat exposure; regardless of family history of mental illness, veterans with high combat exposure developed high rates of PTSD. In a sample of POWs, family history of mental illness, premilitary adjustment problems, and severe childhood trauma were not predictive of PTSD development (18).

In addition to lack of control for trauma severity, variance in assessment methods has affected the results of studies assessing PTSD. The Diagnostic Interview Schedule (DIS; 25), based on DSM-III criteria, was often used despite the low sensitivity of early versions to the presence of PTSD (26), particularly when administered by nonclinicians (7). For example, the DIS was used in community prevalence studies and yielded lifetime rates of 1.0% (10) and 1.3% (27). Three recent studies using DSM-III-R criteria reported significantly higher rates of PTSD. Structured interviews using a DSM-III-R version of the DIS found histories of PTSD in 12.3% of a sample of U.S. women (28), and among 11.3% of women and 6% of men enrolled in an urban health maintenance organization (11). And although NCS procedures reportedly underdiagnose PTSD (9), using the Composite International Diagnostic Interview (29), the NCS yielded a general population lifetime prevalence estimate of 7.8% for PTSD.

Other disorders, most commonly other anxiety disorders, depression, and alcohol abuse, are elevated among those exposed to trauma (9, 30, 31). This comorbidity pattern resembles that found with other anxiety syndromes (32). Studies assessing both current and lifetime diagnoses, however, suggest that with time, co-occurring disorders fade while PTSD persists (7, 33, 34). In the NVVRS (7), the comorbidity of PTSD with a group of other common DIS-detected psychiatric disorders declined from approximately 99% lifetime to approximately 50% at the time of interview.

Particularly in community surveys of those with severe trauma exposure, PTSD has been shown to be central, common, and persistent, consistent with a view of PTSD as a normative response. With this in mind, we present data describing psychiatric disorders and their correlates in a community sample of persons with histories of severe trauma exposure.

Method

Subjects

Our subjects were community-residing former POWs who completed diagnostic interviews and psychodiagnostic testing at the Veterans Affairs Medical Center in Minneapolis (MVAMC). All were male and resided in Minnesota, Wisconsin, or North Dakota. Two were Native American, one was Hispanic, and the rest were White. Their median age was 71 and their median education was 12 years. They were recruited through direct mailings to POWs known to be residing in the area. Approximately two-thirds were receiving at least some of their health care from a VAMC and 7% were involved in mental health care at the time of recruitment. Follow-up telephone contacts with 344 potential subjects resulted in 262 (76%) completed assessments between August 1991 and August 1994. Forty-five (13%) were willing to participate but could not be scheduled due to ill health or distance from the MVAMC; 38 (11%) declined to participate. Fifty-six of the POWs were held by Japan, 191 by Germany, and 15 by North Korea. After complete description of the study to the subjects, written informed consent was obtained.

Measures

All subjects were administered the Structured Clinical Interview for DSM-III-R PTSD module (SCID PTSD; 35) and the SCID Non-Patient Edition (SCID-NP; 36). Psychodiagnostic testing was used to assist in the diagnostic process; results are reported elsewhere (37). All four interviewers were experienced in psychodiagnosis and the assessment of combat-related PTSD. Eight interviews were directly observed by a second rater and five interviews were taped and independently reviewed by two additional raters, allowing three pairs of observations for these cases. There were no disagreements as to the presence or absence of current or lifetime PTSD among these 23 possible pairs of ratings. In addition, there were no disagreements as to the presence or absence of the other most common current or lifetime Axis I diagnoses (noted in Table 1) among 130 possible pairs of ratings. Combat exposure was self-reported via the Combat Exposure Scale (38). Social support was indexed through the sum of responses to items from the Social Reintegration Scale (39). Demographic variables were obtained via a standard POW background questionnaire (40). Information from physical examinations performed shortly after repatriation was reviewed for a random sample of 36 POWs, and their current reports of age at capture, weight loss, and injuries in captivity were corroborated.

Results

Trauma Exposure and Prevalence of Disorders

Sixty-three percent of our sample sustained wounds or injuries in the course of their combat and captivity. Duration of individual combat involvement ranged from 1 to 31 months (mean=4.1, SD=3.7). They had a mean Combat Exposure Scale score of 21.5 (SD=7.2), placing the group in the moderate range of combat exposure (41). Their length of captivity ranged from 1 to 46 months (mean=16.1, SD=14.2). They experienced an average weight loss during captivity of 27.7% (SD=14.2).

DSM-IV redefined PTSD Criterion A (the stressor criterion) to require that intense fear, helplessness, or horror be experienced during trauma exposure. Reexamination of individuals' DSM-III-R Criterion A information indicated that all of our subjects met DSM-IV Criterion A requirements. In addition, DSM-IV adds a Criterion F, requiring that the PTSD symptoms cause clinically significant distress or impairment. One subject positive for current DSM-III-R PTSD did not appear distressed or impaired by his symptoms. His GAF score was 85. The remaining current PTSD cases had a mean GAF score of 65.7 (SD=9.1), which, while suggesting impairment in functioning, may be interpreted as in the moderate range. It is important to note, however, that in PTSD in general, and subjects in this sample in particular, severity of impairment may not be accurately reflected in functional ratings. These veterans have survived and demonstrated an ability to function under the most extreme circumstances. Furthermore, many have reported that an important facet of survival involved hiding their emotions and reactions. Finally, internalizing symptoms such as intrusive recollections, social isolation, avoidance of remindful stimuli, and 50 years of disturbed sleep patterns, may not be adequately indexed in GAF criteria.

DSM-IV also moves one symptom, physiological reactivity on exposure to cues, from Criterion group D (increased arousal) to group B (reexperiencing the trauma). Re-scored SCID data reclassified six subjects from DSM-III-R positive to DSM-IV negative for lifetime PTSD, and three subjects from DSM-III-R positive to DSM-IV negative for current PTSD. DSM-III-R results are reported below.

The mean number of lifetime Axis I disorders per person was 2.3 (SD=1.3, range=0 to 7). PTSD was the most prevalent disorder: 53% (N=140) met lifetime criteria and 29% (N=77) met current criteria (Table 1), comparable to the NVVRS findings noted above (7). The lifetime rate of 37% for alcohol abuse or dependence is somewhat higher than rates noted in the ECS (42) among older males in the general population. As a group, POWs held by Germany had a lower degree of trauma exposure than those held by Japan or in Korea, with corresponding differences in rates of certain disorders. Two multivariate analyses of variance examined the interaction of diagnoses with theater of capture: for lifetime diagnoses, PTSD (F=16.0, df= 2, 260, p<.0001), panic disorder (F=5.1, df= 2, 260, p<.01), and social phobia (F=7.2, df= 2, 260, p<.001) varied significantly by theater of capture. For current diagnoses, PTSD (F=19.9, df=2, 260, p<.0001) and panic disorder (F=5.0, df=2, 260, p<.01) varied significantly by theater of capture. Higher rates of these disorders for POWs held by Japan or in Korea are observed in Table 1.

TABLE 1. Axis I DSM-III-R Diagnoses with Lifetime or Current Rates Greater than 2.5% in a Community Sample of Former Prisoners of War, by Theater of Capture

DSM-III-R Diagnosis: Japan (N=56) Korea (N=15) Europe (N=191) Total (N=262)
Lifetime Current Lifetime Current Lifetime Current Lifetime Current
Posttraumatic stress disorder 84 59 67 47 44 19 53 29
Alcohol abuse/dependence 34 2 53 0 36 6 37 5
Major depression 27 4 13 0 16 4 18 4
Panic disorder 13 9 20 13 4 3 7 5
Social phobia 14 5 7 7 2 2 5 3
Simple phobia 7 5 0 0 3 3 3 3
Generalized anxiety a - 16 - 13 - 7 - 9
Dysthymia a - 4 - 13 - 3 - 4

aThe SCID does not assess lifetime generalized anxiety disorder or lifetime dysthymia.
All figures shown are percentages.

Only 9.5% of our total sample were free of all current PTSD symptoms. Eighty-two percent of subjects without current PTSD also were free from the other 33 current Axis I disorders assessed by the SCID. Fifty-five percent of those with current PTSD were free from the other current Axis I disorders; they had uncomplicated PTSD. Also, 34% of those with lifetime PTSD had PTSD as their only lifetime Axis I diagnosis.

Multivariate prediction of PTSD and other Axis I Disorders

Table 2 summarizes multiple regression equations that used age at time of capture, indicators of trauma exposure, and the social support index to predict current PTSD and the other most frequent current Axis I disorders. Preliminary analyses showed that many theoretically relevant variables were not significantly correlated with Axis I diagnoses and were statistically infrequent. For example, fewer than 2% admitted to having been treated for a mental problem or to a family history of mental problems. Statistical transformations of these skewed variables did not yield significant correlations with Axis I diagnoses, therefore they were not included in Table 2 analyses.

Table 2. Multiple Regression Prediction of Current Posttraumatic Stress Disorder (PTSD) and Other Current Axis I Disorders in a Community Sample of Former Prisoners of War

Predictor variable PTSD Generalized Anxiety Panic Disorder Social Phobia Major Depression Dysthymia Alcohola
Age at capture -.13 b -.15 c -.14 c - - - -
Combat Exposure Scale score (39) .21b - - - - - -
Weight loss during captivity .30 b - - - - - -
Experienced torture/beatings .21 b .15 b - .18 c - - -
Social support .14 b - - - - - -
Multiple R .58 .26 .22 .23 .17 .17 .08
Multiple R 2 .33 .07 .05 .05 .03 .03 .01

a Alcohol abuse or alcohol dependence.
b Regression coefficient significance: p<.01 (two-tailed).
c Regression coefficient significance: p<.05 (two-tailed).
N=262.

The five variables shown in Table 2 were the only significant predictors of Axis I diagnostic status and together they accounted for 33% of the variance in PTSD status. Age at capture was negatively related to PTSD: being older during the period of trauma exposure was a protective factor against later PTSD. Table 2 also shows the much lower power of these variables to predict other Axis I disorders. Only two of the variables were significant predictors of other disorders: age at capture (generalized anxiety and panic disorder) and the experience of torture or beatings (generalized anxiety and social phobia). None of the prediction equations accounted for more than 7% of the variance in the other disorders. Parallel analyses (not shown) for the lifetime diagnoses yielded highly similar results, with the predictors accounting for 33% of the variance in lifetime PTSD status and no more than 7% of the variance in any of the other lifetime Axis I disorders. Separate discriminant analyses (not shown) based on the predictor variables in Table 2 yielded highly significant functions that correctly classified 77% of the lifetime PTSD cases and 80% of the current PTSD cases, using a jackknifed classification procedure. Parallel discriminant analyses attempting to predict the comorbid disorders were non-significant.

If trauma response were nonspecific, a greater scattering of significant regression weights would be observed across Table 2, as would a more robust ability to predict status on disorders other than PTSD. Table 2 shows, however, a concentration of predictive power under the disorder of PTSD, suggesting that trauma response is better represented by PTSD than by the other disorders.

Discussion

In accord with many previous reports, the present findings indicate that PTSD is both a frequent and central consequence of exposure to severe trauma and the diagnostic construct that best represents primary responses to trauma exposure. Consistent with other findings, lifetime PTSD was found in over half (53%) of our subjects, with a substantial minority (29%) still meeting PTSD criteria 40-50 years after trauma exposure. In other words, only 45% of those with lifetime PTSD experienced sufficient symptom reduction to fall below criteria for current PTSD. The present findings also suggest that PTSD without comorbid Axis I diagnoses may be more common in certain trauma-exposed groups than previous studies might suggest.

Community surveys of individuals exposed to severe trauma (6-9) can lead to quite different conclusions than those suggested by studies of clinical samples. In the present study, few subjects had ever received mental health services and all subjects were both combat-exposed and subjected to the hardships of capture and captivity. This trauma exposure was comparable on common dimensions and average levels of trauma exposure were high. To illustrate, we present histories of two veterans who had not sought mental health treatment, and who met criteria for current and lifetime PTSD and no other Axis I disorders:

A 73 year old white male reported a normal childhood, leaving school after 11th grade to work full time. Though married, he was drafted at age 24, trained as a medic, and sent to north Africa in 1943. He provided acute care for combat-wounded Americans, including close friends, many of whom he could not save. He also regrets following orders to not engage in combat; from a secure vantage point, he helplessly watched a German machine gunner kill and wound Americans. He wishes he had removed his Red Cross band and shot the machine gunner. During his 30 months as a POW, he experienced multiple traumatic events including: being captured; being flown to Italy on a plane that was attacked in the air and landed with one engine on fire at an airfield under Allied attack; witnessing the mistreatment, segregation, and eventual disappearance of American Jewish POWs ("they were herded off, never to be seen again"); unsuccessfully trying to stop the execution of a fellow POW by his comrades; and removing dead civilians including children from destroyed bomb shelters.

Upon repatriation, he met his 2 1/2 year old son for the first time. He and his wife raised four children. Because his return to work at a brewery was unsatisfactory, he attended college for two years. He attempted to sell real estate for about a year, eventually returning to his original employer. He reported that, before the war, he was "interested in everything," however, upon return was interested in very little. He now is "very choosy about activities and interests" and his social contact is limited to his family. He has had peptic ulcer disease and chronic arthralgias of his knees since WWII. His chief psychiatric complaints include intrusive recollections (diminishing in intensity somewhat over the years), difficulties falling asleep and staying asleep since the war (averaging only 4 hours per night), and feeling distant from and mistrustful of people outside his family. He has no close friendships and does not associate with other veterans. Any portrayal of disasters or injuries (particularly coverage of the Gulf War and its bombings) provokes nightmares of his POW experiences. He never sought help for these problems, and was uninterested in any new mental health evaluations or treatment. His only Axis I disorder was PTSD, lifetime and current.

A 74 year old white male reported a normal childhood, leaving school after 10th grade to work and play semi-professional baseball. His National Guard unit was activated in 1941 and sent to the Philippines. Japan attacked on December 8, 1941. Following fierce combat with heavy casualties, mainland Allied forces were surrendered April 9, 1942. Together with over 10,000 ill and underfed Americans, he was forced onto the Bataan Death March. As a POW, he witnessed senseless executions and endured beatings, death threats, malnutrition, and multiple untreated medical diseases (43). While laboring, his weight dropped from 155 to 80 pounds until he was too ill to work. In December of 1944 he and 1600 other POWs were forced into the hold of one of the last ships to leave the Philippines. Only half were to survive transport to Japan. The unmarked ship was sunk by American planes after leaving port; he swam to shore. He was recaptured and put on another ship that was hit by American planes near Formosa; he again swam to shore. The journey to Japan (on these "hell ships") included 49 days of confinement in the overcrowded, intensely hot holds of three different ships with little food, water, or sanitation (44). Many POWs became delirious, attacked fellow POWs, and were killed. In Japan he labored in a coal mine for 12 hours per day, 10 days at a time followed by one day off. Rations were about 1000 calories per day. Anyone too ill to work was placed on half-rations. Camp officials made it clear that they were under orders to execute all POWs if America invaded Japan. Instead, the officials abandoned the camp following the bombings of Hiroshima and Nagasaki and the Japanese surrender. Throughout his captivity and post-war life he has maintained an inner posture of resistance. He returned home, married, recuperated from tuberculosis, and began work for the Postal Service where he remained a clerk for 36 years, failing to be promoted "because of my personality". He and his wife raised three children.

His only Axis I disorder was PTSD, lifetime and current. He recalled complaining of nervousness to several nonpsychiatric physicians after WWII but was not referred for mental health services; he reported being told he would "have to live with it". His records indicate he refused tranquilizers. Since participation in the present study, he joined a POW support group that meets twice monthly. He appears anxious and speaks rapidly. He suffers a trauma-related phobia of closed spaces and from most of the PTSD symptoms, chiefly daily intrusive recollections, frequent nightmares, hypervigilance, and survivor guilt. His only friends are a few other POWs of Japan.

Cases such as these appear in community samples and offer insights into chronic untreated psychiatric disorders such as PTSD. Generalizations about the effects of trauma are potentially misleading when drawn from studies of clinical populations that offer insights more specific to treatment-seeking samples. In such samples individuals with Axis I disorders comorbid with PTSD may be overrepresented and vulnerability to trauma's effects may be elevated. See King and King (45) for a discussion of other validity issues in PTSD research.

Being older at the time of trauma exposure appeared to reduce the risk for later PTSD symptoms, however understanding of other protective factors is currently minimal. Research has emphasized vulnerability factors in the search for PTSD's causal bases. More emphasis on protective factors is needed (e.g., 46). Shifting more attention to those who experience few negative effects of trauma exposure might also improve our understanding of recovery mechanisms and contribute to more effective treatment (47).

Our findings that 53% of all the POWs, including 84% of those held by Japan, met full criteria for lifetime PTSD are consistent with earlier reports (1, 2) and indicate the unremitting nature of trauma-related psychopathology in significant proportions of persons exposed to severe trauma. In this, as in a substantial number of other studies including many cited above, trauma exposure was the strongest risk factor for the development of PTSD. Severity of trauma exposure is clearly predictive of PTSD and less predictive of the other disorders commonly observed in trauma survivors. It has been suggested that the longer PTSD lasts, the less important the role of traumatic exposure becomes in explaining posttraumatic symptoms (48). Our data suggest otherwise: 45-50 years later, trauma exposure remains the strongest predictor of PTSD symptoms. Our findings indicate that in the context of severe trauma, PTSD is a persistent, normative, and primary response.

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