• Improve disease measurement to avoid misclassification; for example, including information collected from non-DoD hospitals in studies of hospitalization, obtaining cancer incidence data from existing cancer registries, validating self-reports of health outcomes, and using the least error-prone measures of these outcomes.

  • Better characterize deployment and potentially related adverse environmental influences; for example, collect information on the length and location of deployment or job and task descriptions.

  • Measure and adjust for possible confounding factors; for example, lifestyle factors (such as smoking and risk-taking behaviors) or predeployment physical and psychological health status.

POSSIBLE CAUSES OF MULTISYMPTOM ILLNESS IN VETERANS

During its deliberations, the Update committee held two public sessions at which it heard from numerous interested parties including representatives of veterans’ service organizations and individual Gulf War veterans. The committee was also asked by VA secretary Gen. Shinseki to invite representatives of the VA Research Advisory Committee on Gulf War Veterans’ Illnesses (RAC) to make presentations to the committee on the findings and conclusions in its report, Gulf War Illness and the Health of Gulf War Veterans, released in November 2008, to “ensure that the basis for any differences between these reports can be efficiently and accurately communicated and considered by the latest IOM committee.”

The Update committee concluded, based on a comprehensive review of the human epidemiologic literature, that there is sufficient evidence of an association between deployment to the Gulf War and multisymptom illness (see Chapter 4). The RAC, however, had concluded that the constellation of symptoms called Gulf War illness was caused by exposure to pyridostigmine bromide (PB) and to pesticides during the Gulf War, and that other exposures might also be implicated in Gulf War illness. The Update committee felt it was important to consider this major RAC conclusion regarding the cause of Gulf War illness and the evidence used to support that conclusion in order to respond to Gen. Shinseki’s request. A comprehensive assessment of all the evidence on PB and pesticides exposures in the Gulf War was beyond the Update committee’s formal scope of work. The committee, therefore, limited its assessment to those studies used by the RAC to support its conclusion on the cause of Gulf War illness. The committee believed that its assessment of those RAC studies was best presented in an appendix.

Although the Update committee did not assess the biological plausibility of the link between PB and pesticides and Gulf War illness, in keeping with its charge to examine the strength of association between deployment to the Gulf War and various human health outcomes, the committee critically examined the human exposure studies cited by the RAC as evidence that PB and pesticides are causally associated with Gulf War illness (see Appendix A). However, in contrast to the RAC report, the Update committee found that human epidemiologic evidence was not sufficient to establish a causative relationship between any specific drug, toxin, plume, or other agent, either alone or in combination, and Gulf War illness. Given this important issue, the Update committee also undertook an assessment of the key experimental research studies that were cited in the RAC report as supporting the plausibility of this association. This focused assessment of the experimental literature, summarized in Appendix A, did not meet, in the committee’s opinion, a threshold that would lead to the conclusion that any Gulf War illness-



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