Air Force personnel several years after the Gulf War (Air National Guard, Air Force Reserve, and-active duty personnel), which limits its generalizability to other branches of service and to those who left the service possibly because of illness. The use of self-reported symptoms introduced the possibility of reporting bias, and the low participation rates in two of the four units (62% and 35%) introduced the possibility of selection bias. Nonetheless, symptom reporting and prevalence were similar among the four units. A particular strength of this study was its use of a symptom inventory rather than asking veterans about specific diagnoses, such as CFS, MCS, depression, and various neurologic abnormalities. Its use of a more intensive examination of Gulf War veterans from the index unit—including an additional clinical questionnaire; interviewer-administered modules on major depression, somatization disorder, and panic disorder; a screening physical examination with blinded examiners; and a variety of laboratory tests—provided important additional data even though participation rates were low (62%).

Seabee Cohort

Knoke et al. (Knoke et al. 2000) applied factor analysis to active-duty Seabees in response to the factor analysis conducted by Haley et al. (1997b). The study population was drawn from US Navy construction battalion personnel (Seabees) who were on active duty in 1990 and remained on active duty in 1994, when the study was conducted. The instrument contained 98 symptom questions. Among the 524 Gulf War veterans and 935 nondeployed Seabees, Knoke and colleagues performed three factor analyses: the first on the deployed Seabees, the second on the nondeployed Seabees, and the third on both. Each factor analysis identified five factors that accounted for 80%, 89%, and 93% of the total variance respectively. The factors were insecurity or minor depression (27 symptoms), somatization (13 symptoms), depression (10 symptoms), obsessive-compulsive (seven symptoms), and malaise (seven symptoms). Scores among the three analyses were similar for insecurity or minor depression; higher in Gulf War veterans for somatization, depression and obsessive-compulsive; and higher in nondeployed Seabees for malaise.18 Somatization, depression, and obsessive-compulsive affected an excess of about 20% of Gulf War veterans. The findings were similar to those of Doebbeling (2000), Fukuda (1998) and Ismail (1999) and consistent with findings in a civilian population with CFS (Nisenbaum et al. 1998). They concluded that, unlike the results of the Haley et al. (1997b) study of Seabee reservists from one unit, there was no evidence of a unique spectrum of neurologic injury. While the Knoke et al. study used a larger population than Haley et al., this study still used personnel from a single service, so its generalizability is limited. Because participants were active-duty personnel by design, the results cannot be generalized to retired or reserve personnel who might have been more symptomatic. Nonetheless, the authors’ careful examination of the methods and findings of Haley et al. in a very similar population makes this study quite useful.

Haley et al. Seabee Cohort and Validation Study

Haley and collaborators (Haley et al. 1997b) studied a battalion of naval reservists called to active duty for the Gulf War (n = 249). More than half the battalion had left the military by the time of the study. Of those participating, 70% reported having had a serious health problem since returning from the Gulf War and about 30% reported having no serious health problems. The


Factor scores used to compare the groups were computed from the regression coefficients of the Gulf War veteran factor analysis, standardized for both groups by subtracting the median and dividing by the semi-interquartile range of the score for the Gulf War veteran group.

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