and a lack of indication as to whether the veterans had sustained injuries during deployment or were using pain medication at the time of the survey.
A similar study by Cherry et al. (2001a,b) 6-8 years after the Gulf War also used a pain manikin to identify whether and where veterans had experienced pain for at least 24 hours in the preceding month. Among the 9588 male and female UK Gulf War veterans in all service branches, 12.2% reported widespread pain on a manikin compared with 6.5% of 4790 nondeployed veterans; widespread pain was considered to be present if the manikin showed axial skeletal and contralateral body pain. CWP was associated with exposure to insect repellent, medical attention, and side effects of nerve-agent prophylaxis.
Several studies have reviewed the presence of chronic pain in veterans, but the definition of chronic pain varied with the study (Hyams et al., 1996; Kuzma and Black, 2006; Thomas et al., 2006). Kuzma and Black (2006) noted that many studies of Gulf War veterans reported increased pain symptoms that could be clustered into CWP, but the terminology used in the studies was not consistent and included joint pain and general aches and pain; these pain clusters may or may not have met the ACR criteria for CWP.
The diagnosis of fibromyalgia is based entirely on symptoms and physical examination; there are no pathologic or laboratory tests with which to confirm it. Among the available cross-sectional studies that include both Gulf War deployed and nondeployed veterans, only Eisen and colleagues (2005) used the full ACR case definition of fibromyalgia, including criteria based on physical examination. The study by Smith and colleagues (2000) found no association between Gulf War deployment and hospitalization for fibromyalgia. That finding does not appear inconsistent with positive findings in the Eisen et al. study, in that few cases of fibromyalgia are severe enough to warrant hospitalization. Notably, the prevalence of a diagnosis of fibromyalgia in the Eisen et al. study is about 300 times the prevalence of hospitalization for fibromyalgia in the Smith et al. study. Two secondary studies from Iowa and Canada both found significantly increased fibromyalgia symptoms among deployed veterans compared with nondeployed veterans, but lacked a physical examination to enable the use of the full criteria for diagnosis. In conclusion, largely on the basis of the Eisen et al. study, which used the criteria of the ACR for diagnosis of fibromyalgia but could have been subject to unrecognized selection bias, there is a higher prevalence of fibromyalgia among deployed Gulf War veterans than among nondeployed veterans.
The committee reviewed one primary study and three secondary studies on Gulf War deployment and CWP. Although each of the studies found a higher prevalence of CWP in deployed than nondeployed veterans, all had considerable limitations. In Ang et al. (2006), the prevalence of CWP was found to increase both with increased combat exposure and with increased perception of life stress at the time of deployment; the study is limited in that only veterans with no pain 5 years after the conflict were evaluated 10 years after the conflict. The Stimpson et al. study (2006) also found an increase in CWP associated with deployment. The other two secondary studies also showed more CWP in deployed than in nondeployed veterans.
The committee concludes that there is limited but suggestive evidence of an association between deployment to the Gulf War and both fibromyalgia and chronic widespread pain.