# Presentation: 342286

## THE PSYCHOLOGICAL RISKS OF VIETNAM: A A REVISIT WITH NEW DATA AND METHODS (Science, Volume 313: 979 – 982, 2006)

- AUTHORS:
- Bruce P. Dohrenwend, J. Blake Turner, Nicholas A. Turse, Ben G. Adams, Karestan C. Koenen, and Randall Marshall
- SUPPORTED BY:
- Grant R01 MH059309 from the National Institute of Mental Health and grants from the Spunk Fund, Inc.
- March 7, 2007

## NVVRS: No Stranger to Controversy

- 1988 – NVVRS 30.9% Lifetime; 15.2% Current PTSD.
- 1988 – CDC 14.7% Lifetime; 2.2% Current.
- NOTE: Evident flaws in the CDC measure  explained why the CDC rates were so low.  Attention turned to the more complicated question of why the NVVRS rates were so high.

## Skepticism about the NVVRS Rates

- Here are Wessely and Jones giving voice to this skepticism:
- “This [the NVVRS] was a landmark study, of immense political importance, and played a major role in the rehabilitation of the Vietnam veteran in the eyes of society, but one not immune to criticism – not the least because of the ‘remarkable’ prevalence of psychiatric disorder reported.  Perhaps the most important methodological drawback comes from the way in which combat exposure was assessed.  First of all, it was based . . .on ‘retrospective self reports of events and circumstances that occurred approximately 10 to 20 years prior to data collection.’
- We know now that retrospective reports of war experience are coloured by current circumstances and the political and social climate that follows the war.   . . . . it is highly likely that there has been a gradual ‘inflation’ of traumatic memories to fit with the changing views of the Vietnam War.”

## The 30.9% to 15% Puzzle

- For example, skeptics raised the question of why the NVVRS found twice as many men (30.9%) suffering from PTSD as some historians estimated had served in combat (15%).
- Critics pointed to a host of possible culprits including recall bias, exaggeration, and outright lying.

## Why we thought we could usefully address the controversy

- In the course of our on-going research with the NVVRS data set, we discovered a treasure trove of historical material and data from military records that were not available at the time of the NVVRS was conducted.
- We also had been working with tape-recorded data from detailed diagnostic examinations of a subsample of the NVVRS veterans.
- Before I summarize what we did with these resources, let’s review some of the most important features of the NVVRS.

## National Vietnam Veterans Readjustment Study (NVVRS):

- 3.14 million U.S. men served in or around Vietnam (the Vietnam theater of operations)
- 1200 member NVVRS male Theater sample drawn on a full probability basis from veteran records in personnel files (201 files).
- 260 male Theater veterans subsampled from respondents in 28 Standard Metropolitan Regions (SMRs).
- Subsample veterans received clinical diagnostic examinations conducted by experienced doctoral level clinicians with the Structured Clinical Interview for Diagnosis (SCID).
- Suitably weighted to reflect stratum differences in sampling rates, the results can be generalized to the populations from which the Theater veterans were drawn.
- The rate of current PTSD estimated by the NVVRS measure used in the sample as a whole is at least as high (15.4%) in the subsample in the 28 SMRS as the rate for veterans living elsewhere in the U.S.(14.3%).

## Our approach

- Delved into military histories to come to terms with the description of Vietnam as a “low intensity war.”  “WAR WITHOUT FRONTS” A BETTER DESCRIPTOR.
- Used military records and historical accounts to develop measures of war-zone exposure (MHMs) that are prospective and independent of the veterans’ retrospective reports.
- Relied on clinical diagnoses in the small subsample of NVVRS veterans.
- Used impairment of functioning and seriousness ratings by the clinicians to distinguish impairing from milder PTSD.
- Used MMPI validity scales and data from military personnel files (201 files) and other military records to check on the credibility of the veterans’ reports.

## MAIN MEASURES AND RESULTS

- First, the record-based measure of probable severity of exposure to war-related PTSD

## Probable Severity of Exposure to War-Zone Stressors

**Veteran’s military occupational speciality (MOS)**
**Monthly casualty rate (KIA) during veteran’s service in Vietnam**
**Casualty rate (KIA) in veteran’s larger military unit (e.g. Division in Vietnam)**.
**Level of casualties (KIA) in veteran’s company during veteran’s service in Vietnam**

_**Composite**_**. These four measures are combined into an overall measure of probable severity of exposure to war-zone stressors.  This composite is a four category variable (very high, high, moderate, and low exposure probabilities).**

**Notes:**
1.  MOS: High – (e.g., infantrymen, medics, etc); 23.1%
	     Middle – (e.g. (motor transport operators, armored vehicle repairmen); 16.6%
	     Low – (e.g., finance specialists, storage specialists); 60.3%

2.  Monthly casualty rate: Ranged from 4.20/1000 in February 1968 during the Tet offensive of 0.11/1000 in November 1971 shortly before the end of U.S. fighting in Vietnam.  Veterans were classified on this measure into tertiles: Highest, middle and lowest level of monthly casualties depending on the actual casualties during the months he was in Vietnam.

3  Casualty rate in veterans larger military unit (e.g. Division—15,000 – 22,000 men): These ranged from a high of 78.3/1000 for 1st Marine Division to a low of 0.6/1000 for the Engineering Command.  We divided units into 5 levels with the result that 60.1% were in low casualty rate units, 8.3% in moderate; and the remainder in 3 levels of high.

4  Levels of casualties in veteran’s company (120 -200 men) during his service: 56.5% in companies with 0 KIA during his tour; 14.8% in companies with only 1 KIA during his tour; 19.5% in companies with 2 – 9 KIAs during his tour; and 19.3 in companies with 10 or more KIA during the moths the veteran served in Vietnam.

## Fig 1. Percents of veterans with self-reported high and self-reported low war-zone stress exposure by military/historical measure (MHM) of probable severity of exposure to war-zone stressors (full sample n=1,189, excluding 11 veterans with missing data on self-reported war-zone exposure). 

**Fig 1.** Percents of veterans with self-reported high and self-reported low war-zone stress exposure by military/historical measure (MHM) of probable severity of exposure to war-zone stressors (full sample *n*=1,189, excluding 11 veterans with missing data on self-reported war-zone exposure).

## NVVRS Algorithm for Current PTSD in Full Sample

- Consists of a calibration of self-report symptom scales mainly against the SCID to approximate a clinical diagnosis of current PTSD.
- This measure is the basis for the published NVVRS current prevalence rate of 15.2%.
- The NVVRS algorithm focuses only on current prevalence.
- The often quoted 30.9% lifetime rate was extrapolated from the results of the SCID diagnoses in the subsample.

## Diagnoses of War-Related PTSD

- The Structured Clinical Interview for Diagnoses (SCID) (Spitzer et al.)
- Experienced doctoral level clinicians who were not VA employees.
- Examinations were tape recorded permitting careful reliability checks.
- The clinicians obtained information that made it possible for us to distinguish war-related PTSD from PTSD with first onsets related to events prior to or after service in Vietnam.

## Table 1. SCID-diagnosed lifetime and current rates of PTSD by time of first onset in subsample of male theater veterans  n=256 (standard errors in parentheses).* 

- Lifetime Rates

- Current Rates**

- Table 1. SCID-diagnosed lifetime and current rates of PTSD by time of first onset in subsample of male theater veterans  n=256 (standard errors in parentheses).*

***Excluding 3 veterans for whom time of onset could not be established (2) or for whom sample weight was missing (1).**
**** “Current” refers to the presence of criteria-meeting disorder in the 6 months prior to the diagnostic examination**

## Impairment of Functioning

- When the NVVRS was conducted, a PTSD diagnosis (DSM-III-R) did not require, as it does now (DSM-IV), the presence of impaired functioning.
- Skeptics speculated that the PTSD symptoms measured in the NVVRS might indicate relatively mild psychological distress rather than true disorder.
- The subsample diagnoses included ratings of severity and impairment useful for addressing this question.

## War-related first onsets of PTSD 

**Functioning **

- War-related first onsets of PTSD** **

**Table 2**.  Estimated impairment on the Global Assessment of Functioning (GAF) scale in the 260-member subsample of veterans diagnosed by experienced clinicians using the Structured Clinical Interview for Diagnosis (SCID)  as having no lifetime war-related first onsets of PTSD (past or current), past war-related first onsets of PTSD, and war-related first onsets of PTSD that remained current.  Sample *n*’s are in parentheses and percentages are based on data weighted to reflect the complex sampling design.*.* (Omitted from the analysis are 4 veterans with pre-war onsets, 2 missing onset information, l missing sampling weight, and 6 missing impairment scores).

## RECORD CHECKS ON REPORTS OF CRITERION A TRAUMATIC STRESSORS

- For the overwhelming majority who were given diagnoses of war-related PTSD, it is plausible to believe that they in fact experienced Criterion A traumatic stressors.
- Confirmatory evidence was could not be found for only 8 out of 90 with war-related first onsetS; for only 2 of the 8 did record information seem outright contradictory.

## Table 3.  Percents of lifetime first onsets (past plus current) and percents of current first onsets of war-related PTSD in the 260-member SCID-diagnosed subsample of veterans with and without adjustments for the requirements of impairment and/or independent documentation of traumatic exposure.  Sample n’s are in parentheses and percentages are based on data weighted to reflect the complex sampling design. (Omitted from the analysis are 4 veterans with pre-war onsets, 2 missing onset information, and l missing a sampling weight.)

**Table 3.**  Percents of lifetime first onsets (past plus current) and percents of current first onsets of war-related PTSD in the 260-member SCID-diagnosed subsample of veterans with and without adjustments for the requirements of impairment and/or independent documentation of traumatic exposure*. * Sample *n*’s are in parentheses and percentages are based on data weighted to reflect the complex sampling design. (Omitted from the analysis are 4 veterans with pre-war onsets, 2 missing onset information, and l missing a sampling weight.)

## The Dose/Response Relationship

- We have used the firmest measures we have available – MHM exposure and SCID diagnoses of war-related PTSD in the subsample – to investigate dose/response

## Figure 2: Dose/response

##  CONCLUSION 1: DISSEMBLING OR EXAGGERATON

- We found little evidence of dissembling or subtler forms of exaggeration in the symptom reports by the veterans.

## CONCLUSION 2:PSYCHOLGICAL COSTS

- Our onset rates of about 1 in 5,  with 1 in 10 still current more than 10 years after the war are substantial.
- These are rates of war-related PTSD that, at the worst point in the course, involved substantial impairment of functioning even for those whose PTSD had remitted by the time of follow-up more than 10 years after the war.

## CONCLUSION 3:DOSE/RESPONSE

- The nature of this toll is especially evident in the strong dose/response relationship between severity of exposure to war-zone stressors and PTSD.
- The dose is measured by indicators of exposure that are clearly antecedent and independent of the veterans’ recall and the symptoms of the PTSD response by state if the art diagnoses by experienced clinicians.
- The resulting association is about as near as we can come to demonstrating a causal relationship in cross-sectional, observational research of this kind.
- It may be the most important result from our research.

## CONCLUSION 4: COURSE OF WAR-RELATED PTSD

- The trajectory for most veterans with war-related PTSD that causes substantial impairment is toward amelioration or complete remission.
- These trends toward recovery over time cannot be explained entirely by treatment administered by mental health professionals because less than half the veterans with past war-related PTSD (44.9%) received such treatment.**  **
- Tremendous need to follow up the NVVRS cohort to learn more about the course of war-related PTSD.

##  The End