ated explanatory theories, so they were understandably not widely embraced by veterans or their families.
The Vietnam experience contributed case criteria and a label for posttraumatic stress disorder (PTSD). The disorder itself was not new, but the recognition of it and the eventual incorporation of PTSD into the standard medical and psychiatric diagnostic coding systems (ICD-9 and DSM-III [Diagnostic and Statistical Manual], respectively) date from the Vietnam era. Additionally, concerns regarding health effects related to Gulf War exposures are similar to the concerns that emerged regarding Agent Orange exposure for Vietnam veterans.
Health problems in Gulf War veterans, then, are studied with the recognition of their potential similarity to problems in other conflicts, but not necessarily with the acceptance of prior causal explanations. Most studies take Gulf War deployment (yes/no) as the measure of exposure, because the set of potential causal factors for postwar health problems was not well understood at the time of the conflict and is not much more clearly understood today. A few studies, however, focus on a specific chemical or biological exposure (again, usually yes/no rather than a graded scale). The studies discussed below typically are designed to detect an unusually high frequency or severity of health problems in a group of veterans who served in the Gulf, compared to either veterans of the same period who were not deployed or a more general population who did not serve.
Two studies focused on mortality among Gulf War-deployed veterans compared to similar veterans not deployed to the Gulf. The study by Kang and Bullman (1996) used the Beneficiary Identification and Records Locator System (BIRLS) of the Department of Veterans Affairs (VA) to track deaths in nearly the entire population of deployed Gulf War veterans. Death rates in the deployed group were compared with the rate in a similar-sized control group of active duty, National Guard, and reserve personnel who served during the Gulf War period but were not deployed. Deaths for any cause were tracked through September 1993. Writer et al. (1996) compared deaths occurring during the conflict among the population of deployed veterans and among a large population of nondeployed veterans in the 1990–1991 period. Data on deaths were obtained from Report of Casualty forms (DD Form 1300).
The Kang and Bullman study is perhaps more directly relevant to the committee's charge, because it was designed to detect excess mortality among deployed veterans in at least the immediate post war period. No such excess was found, except for deaths attributed to accidents. A similar finding was also noted among Vietnam veterans and may reflect a set of risk-taking phenomena among veterans returning from conflict rather than a chemical, biological, or psychological exposure leading to physiological change. During the 1998 meeting of