branch, and military status, Black et al. (2004) found that nonwhite Gulf War veterans were at almost twice the risk of an anxiety disorder as white veterans (OR 1.9, 95% CI 0.7-5.3).

Hoge et al. (2002) assessed the incidence of first hospitalization for a mental disorder in active-duty military personnel in 1990-1999. The rates of hospitalization per 1000 person-years were 9.34 for whites, 9.25 for Hispanics, 8.30 for blacks, 5.97 for Asians and Pacific Islanders, and 18.27 for American Indians and Alaskan Natives. Fontana et al. (2000) found that among U.S. peacekeepers in Somalia, PTSD symptoms were more severe in blacks, although there was no adjustment for socioeconomic factors in the model.

Age

Research results on age as a risk factor for PTSD and other psychiatric disorders are mixed. Studies of Vietnam veterans (Bremner et al. 1993; CDC 1988; Green et al. 1990b; Kulka et al. 1990) and Gulf War veterans (Wolfe et al. 1999) generally found lower age to be a risk factor for PTSD. Kulka et al. (1990) in the NVVRS found that older men (born before 1945) had a lower prevalence of PTSD (4-10%) than those born later (18-19%).

Ikin et al. (2004) found that although Australian Gulf War-deployed veterans were at increased risk for any postwar anxiety disorder compared with nondeployed veterans, the risk did not vary significantly among four age groups (less than 20 years old, 20-24, 25-34, and 35 and higher). Black et al. (2004) also found that being 25 years old or younger did not significantly increase the risk of having a current anxiety condition among Gulf War veterans (OR 1.3; 95% CI 0.8-2.0). During the 1990s, however, active-duty military personnel aged 18-24 were at greater risk for hospitalization for a mental disorder than older veterans (Hoge et al. 2002).

Seal et al. (2007) found that active-duty Operation Enduring Freedom (OEF) and Operation Iraqi Freedom (OIF) male veterans 18-24 years old were more likely to have a diagnosis of PTSD or any other mental health disorder than were older veterans. The risk of having a diagnosis of PTSD or any mental health diagnosis decreased with increasing age. Compared with veterans 40 years and older, the relative risk for PTSD was 8.88 (95% CI 7.49-10.54) for the youngest veterans, 6.91 (95% CI 5.82-8.21) for those 25-29 years old, and 6.07 (95% CI 5.05-7.28) for those 30-39 years old.

Developmental History and Early-Life Stress

Numerous epidemiologic studies of Vietnam and Gulf War veterans and of civilians have found that childhood trauma from physical or sexual abuse is a risk factor for PTSD, regardless of later combat exposure. The strongest evidence of the impact of early-life stress comes from large studies of Vietnam veterans (Fontana and Rosenheck 1994a; Kulka et al. 1990) and Gulf War veterans (Sutker et al. 1995b).

Fontana et al. (1994a) analyzed data from the NVVRS, assigning weights to the major contributors to PTSD in female veterans. A history of child abuse contributed nearly as much to the risk of having PTSD as did military sexual trauma although combat exposure was twice as likely to contribute to the risk of PTSD (Fontana and Rosenheck 1994a). King et al. (1999) also found that a history of early-life trauma was linked to the development of PTSD in male and female Vietnam veterans; it also predicted the likelihood of stressful life events after the war. Childhood sexual and physical abuse is common in Gulf War and Vietnam veterans seeking treatment for psychiatric disorders including PTSD, with studies that assessed this endpoint



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