subsample for phase I of 7924 U.S. Army Vietnam-theater veterans and 7364 Vietnam-era veterans. In phase I, the veterans participated in telephone interviews about their psychosocial health, physical health, and reproductive outcomes. In phase II conducted in 1985-1986, 3317 of the theater veterans and 3126 of the era veterans were invited to participate in a comprehensive health examination to determine the effects of war-zone deployment on psychosocial characteristics (CDC 1988a). Of the theater and era veterans, 2490 (75%) and 1972 (63%), respectively, were enrolled in phase II, which included an examination of psychologic health. The investigators used the DIS and the Minnesota Multiphasic Personality Inventory to assess the veterans for PTSD, alcohol abuse, drug abuse, generalized anxiety, and depression. Six characteristics were controlled for: age at entry into the Army, race, score on the enlistment general technical test (a measure of mental aptitude), enlistment status (drafted or volunteered), year of entry into the Army, and primary military occupational specialty (tactical or nontactical). Vietnam veterans were significantly more likely than era veterans to meet the DIS criteria for generalized anxiety (OR 1.5, 95% CI 1.1-2.1) and depression (OR 2.0, 95% CI 1.4-2.9) in the month prior to examination. Only 2.2% of the theater veterans met the full DIS criteria for combat-related PTSD in the previous month (current), although 14.7% had ever met the criteria (lifetime); results for era veterans were not given.
The congressionally mandated NVVRS constituted nationally representative cohorts of male and female Vietnam theater veterans, era veterans, and civilians; the veteran cohorts were randomly chosen from among all military personnel who had served on active duty during the Vietnam War and who had left service as of September 1987 (Kulka et al. 1990; Weiss et al. 1992). All study participants were interviewed in November 1986-February 1988. The NVVRS was created to determine the prevalence of specific psychiatric disorders and other adjustment problems, both during the course of life (as a measure of predisposing factors) and at the time of the interview. It also included self-reports of war-zone stressor exposures used to create a war-zone stress index to characterize theater veterans as having been subjected to “high exposure” or “low or moderate exposure.” A sample of veterans and civilians was obtained from the National Personnel Records Center, the DMDC, and a list developed by VA of all female theater veterans. The NVVRS conducted a total of 3016 interviews, in what was called the National Survey of the Vietnam Generation, with 1200 male theater veterans, 412 male era veterans, 448 male civilians, 432 female theater veterans, 304 female era veterans, and 218 female civilians. The NVVRS also included a preliminary validation component for the survey-based PTSD measures and a clinical-interview component. Response rates were over 83% for Vietnam-theater veterans, 76% for Vietnam-era veterans, and 70% for civilians of those sampled and eligible. Detailed reviews and analyses of military data records were conducted to identify potential differences between veteran respondents and nonrespondents. Although no significant differences were identified, the investigators weighted the data for all the analyses to account for interview-level nonresponse and different probabilities of selection in the civilian cohort. The investigators also controlled for age, race or ethnicity, and female veteran occupation. The occupation of the female veterans was important because many of them were likely to be nurses and therefore to have different exposures to war-zone stressors than their male counterparts (Kulka et al. 1990). Although the DIS was used to interview both veterans and civilians, only a subsample of 260 veterans underwent a semistructured clinical interview by experienced mental-health professionals to also diagnose PTSD and to validate the use of the interview instrument for PTSD used by the researchers. A composite PTSD diagnosis for the subsample was made based on the interviews,