(11.8% vs 4.9%, p < 0.001). The hazard ratio for death from external causes in theater veterans with PTSD compared with those without PTSD was 2.3 (95% CI 1.4-3.9). External causes of death were motor-vehicle collision, accidental poisoning, suicide, homicide, and injury of undetermined intent. The hazard ratio was adjusted for race, Army volunteer status, Army entry age, Army discharge status, Army illicit drug use, age at interview, and intelligence.

Price et al. (2004) used data from phase III of the VES survey, conducted in 1996-1997, to assess the effect of PTSD on the risk of nonfatal suicidality (suicidal thinking or behavior) from 1972 to 1996 in 637 male Vietnam-theater veterans. Comparing veterans with PTSD to those without PTSD, the hazard ratio was 1.51 (risk limits 0.65-3.48); during that time, nine of 943 veterans in the cohort database died from suicide, and 15.7% of the 641 veterans interviewed in 1996-1997 reported suicidality. MDD was also significantly associated with nonfatal sucidality over the 25 years (hazard ratio 3.21, risk limits 1.93-5.34), as was drug dependence (hazard ratio 2.06, risk limit 1.31-3.24) but not alcohol dependence (hazard ratio 1.18, risk limit 0.84-1.68). Both PTSD and drug dependence prolonged the duration of suicidality; although the influence of PTSD remaining high during the 25 years, the influence of drug dependence on suicidality decreased with time.

Kramer et al. (1994) assessed the impact of PTSD on suicidality in 131 Vietnam veterans who lived in the community, 64 veterans in a clinical outreach program, and 37 veterans who were psychotherapy patients. PTSD and suicidality were assessed with the Schedule for Affective Disorders and Schizophrenia-Lifetime Version. Suicidal thoughts were more highly correlated with lifetime and current PTSD (p < 0.001) than were suicidal behaviors.

Summary and Conclusions

The results of the studies based on cohorts from the Vietnam War and the 1991 Gulf War demonstrate consensus and divergence with regard to the strength of an association between deployment and suicide or accidental death. The conclusions on suicide and accidental death are presented separately.

One study from the Vietnam era provides evidence of a dose-response relationship between the degree of traumatic injury suffered during deployment and suicide. Considering that study with two other primary studies, one in the early followup period after the Vietnam War and the other a study of female Vietnam veterans, the committee concluded that there is sufficient evidence that, at least for some period after deployment, Vietnam veterans were at increased risk of dying from suicide compared with nondeployed veterans. That conclusion is supported in part by the recent report of a higher suicide rate in deployed OIF troops in 2005 than in the Army in that year. The risk may also be increased for some veteran groups, namely, those suffering from PTSD, depression, or substance abuse, and those with specific war-related traumas. The association was not strongly supported by studies conducted in those deployed to the Gulf War, but the brevity of that war and the limited involvement of troops in the region may have kept the statistical power of those studies too low to detect an association between a rare effect—suicide—and deployment.

The committee concluded that there is also sufficient evidence for an association between deployment and accidental death, again, especially potent during the early years postexposure. These conclusions are based on evidence from both the Vietnam War and the Gulf War and from primary and secondary studies.

The studies considered in this section have limitations. In the United States, the coding of mortality data changed substantially in 1999 from ICD-9 to ICD-10, and the number of deaths

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