men (RR 1.13, 95% CI 1.04-1.23). Serving as support for the ground war without being in direct combat was associated with a greater risk of drug-related hospitalizations in men (RR 1.42, 95% CI 1.03-1.96) and women (RR 3.61, 95% CI 1.70-7.66). The limitation of this study is that it examined only hospitalizations and thus was not representative of most psychiatric disorders which require outpatient treatment rather than hospitalization. It also did not include veterans who left the military after the Gulf War.
Table 5.2 summarizes the results of the primary studies on psychiatric outcomes.
Findings on many other major cohorts of Gulf War veterans support what has been found in primary studies (Gray et al. 2002; McCauley et al. 2002). The most important limitation was their reliance on self-reports of “physician-diagnosed disorders” rather than measurement of symptoms with validated questionnaires or face-to-face interviews. In the UK cohort studied by Unwin et al. (1999), investigators asked some questions taken from the Mississippi Scale for Combat-Related PTSD but did not administer the entire questionnaire. They found that “post-traumatic stress reaction” was about 2-3 times more likely in deployed than in two nondeployed groups. The magnitude of the increase is consistent with that seen in the primary studies. Several other secondary studies have found an association between serving in the Gulf War and psychiatric disorders (Holmes et al. 1998; Magruder et al. 2005; Simmons et al. 2004; Steele 2000; Stretch et al. 1996a; Stretch et al. 1996b; Sutker et al. 1995).
Two well-designed studies using interview-based assessments have found that several psychiatric disorders, notably PTSD and depression, are 2-3 times more likely in Gulf War-deployed than in nondeployed veterans (Black et al. 2004b; Wolfe et al. 1999b). Direct interviews are labor-intensive; so many other studies administered validated symptom questionnaires. The findings were remarkably similar, that is, an overall increase in magnitude, by a factor of 2-3, of psychiatric disorders. When war exposure was assessed with symptoms, studies characteristically showed higher rates, particularly of PTSD, in veterans who had more traumatic war experiences than in those with lower levels of exposure. In other words, studies found a dose-response relationship between the degree of traumatic war exposure and PTSD. Nevertheless, deployment to a war zone without direct combat exposure is a traumatic war exposure, considering that one well-designed study found deployment without combat to increase the risk of psychiatric disorders by about 60% (Ikin et al. 2004).
Other risk factors were war preparedness, enlisted status (possibly correlated with war preparedness), smoking, and previous psychiatric diagnosis. Two studies indicated that severe PTSD symptoms would worsen over time, and so suggested that careful assessment of the longitudinal course of postwar psychiatric conditions is needed.
It is confirmatory to see that the primary studies, regardless of their techniques of ascertainment or their target population, reported almost identical conclusions regarding the psychiatric outcomes of Gulf War deployment for veterans, that is, that depression, substance abuse or dependence, and anxiety disorders, especially PTSD, were increased in Gulf War veterans after deployment, and that symptom severity was associated with the level of war stress.