although the Gulf War cohort had a higher frequency of symptom reporting. Further, this study did not identify in this cohort of Gulf War veterans the six factors characterized by Haley and colleagues (1997b) in a separate factor analysis study described in the next section. The authors interpreted their results as evidence against the existence of a unique Gulf War syndrome.
Exposure–symptom relationships. In the U.K. Gulf War cohort, most self-reported exposures were associated with all of the health outcomes, which was also true for the two comparison cohorts (Unwin et al., 1999). The authors interpreted these findings as evidence that the exposures were not uniquely associated with Gulf War-related illnesses. Within the Gulf War cohort, two vaccine-related exposures—vaccination against biological warfare agents and receiving multiple vaccinations—were associated with meeting the case definition for the chronic multisymptom illness developed by CDC researchers. A recent analysis of the data on a subcohort of U.K. veterans found that receiving multiple vaccinations during deployment was associated with five of the six health outcomes examined (including multisymptom illness as defined by the CDC) (Hotopf et al., 2000). Vaccine-related findings are discussed in greater detail in Chapter 7.
One of the first epidemiologic studies of U.S. Gulf War veterans was of more than 4,000 active duty and reserve personnel from the states of Pennsylvania and Hawaii (Stretch et al., 1995). Veterans deployed to the Gulf reported higher prevalence than nondeployed veterans of 21 out of 23 symptoms on a symptom checklist (although the total response rate was only 31 percent). Overall, deployed veterans were about two to four times more likely than nondeployed veterans to report each symptom.
The symptom experience of two cohorts of Gulf War veterans from Massachusetts (Ft. Devens) and New Orleans was studied by Proctor and colleagues (1998). In comparison with veterans deployed to Germany during the Gulf War era, stratified random samples of both Gulf War cohorts reported elevated prevalence of 51 out of 52 items on a health symptom checklist. The greatest differences in prevalence of reported symptoms were for dermatological (e.g., skin rash, eczema, skin allergies), neuropsychological (e.g., difficulty concentrating, difficulty learning new material), and gastrointestinal symptoms (e.g., stomach cramps, excessive gas). The study’s nearly 300 subjects represented a stratified random sample of 2,949 troops from Ft. Devens and 928 troops from New Orleans, both consisting of active duty, reserve, and National Guard troops. These cohorts were also the focus of several in-depth studies of stress-related disorders (see discussion later in this chapter).
Women veterans from the Air Force were studied by Pierce (1997). The study examined a stratified sample of 525 women (active duty, guard, and reserve) drawn from all 88,415 women who served in the Air Force during the Gulf War era. Women deployed to the Gulf War, in comparison with women