diarrhea, feeling bloated, stomach pain, heartburn, constipation, vomiting (Cherry et al., 2001a); flatulence, or burping (Unwin et al., 1999); and digestive, stomach, and intestinal disorders (Simmons et al., 2004) than nondeployed veterans. Australian Gulf War veterans also self-reported more moderate to severe flatulence or burping (OR 1.6, 95% CI 1.3-2.1), indigestion (OR 1.7, 95% CI 1.3-2.3), diarrhea (OR 2.4, 95% CI 1.6-3.5), stomach cramps (OR 2.2, 95% CI 1.5-3.3), constipation (OR 1.8, 95% CI 1.0-3.0), and nausea (OR 2.5, 95% CI 1.4-4.5). Although the Australian study used a postal questionnaire to initially ask veterans about having received a physician’s diagnosis of or treatment for a medical condition, the veterans were later asked in person about their responses by a physician. The physician then determined whether the diagnoses or treatments reported on the questionnaire and discussed with the patient were a possible or probable diagnosis based on the veterans’ responses. Based on this approach (which added a level of medical judgment to the self-reports but did not verify the self-reported diagnoses with additional testing such as an endoscopy or x-ray), compared with nondeployed veterans, deployed veterans were more likely to have a possible or probable diagnosis of stomach or duodenal ulcers (OR 1.6, 95% CI 1.1-2.75) and irritable bowel syndrome (OR 2.4, 95% CI 1.4-4.3) (Sim et al., 2003). Canadian Gulf War veterans reported more digestion problems other than stomach ulcers that did nondeployed Canadian veterans (13.4% vs 6.6%) (Goss Gilroy, 1998).
A recent systematic review evaluated the risk of developing painful conditions among Gulf War deployment versus nondeployed veterans. Using six studies (Cherry et al., 2001a; Gray et al., 2002; Kang et al., 2000; Knoke et al., 2000; Sostek et al., 1996; Steele, 2000). Thomas et al. (2006) found that pain from various conditions was more likely to occur in deployed veterans, and the most significant effect was seen with abdominal pain (OR 3.23, 95% CI 2.31-4.51).
In summary, numerous studies indicate that Gulf War veterans self-report more GI symptoms than nondeployed veterans. Most of these studies are limited because their methods are insufficient to determine a clear association between deployment and the onset of a functional disorder by standard Rome criteria (Drossman et al., 2006) or of a structural disorder (Drossman and Ringel, 2004). Furthermore, the diagnosis of structural diseases should be validated by medical records because physicians not infrequently place an organic label on a patient’s symptoms (for example, gastritis or peptic ulcer) without performing diagnostic studies, and this will confound the diagnosis in a survey, particularly if the data are based on the subjects’ recollections of physicians’ diagnoses.
Other studies have evaluated hospitalizations and mortality of Gulf War veterans for digestive diseases. To avoid criticism when comparing deployed personnel with nondeployed personnel as may have occurred in the Gray et al. (1996, 2000) hospitalization studies (creating a “healthy deployer” effect), Smith et al. (2006) compared postdeployment hospitalizations for active-duty military personnel deployed to the Gulf War, deployed to southwest Asia after the war, or deployed to Bosnia. Hospitalizations were based on ICD-9 discharge diagnoses from military hospitals from August 1, 1990, to December 31, 2000. Active-duty personnel deployed to Bosnia were at reduced risk of hospitalization for digestive system diseases or conditions compared with Gulf War veterans (HR 0.60, 95% CI 0.54-0.67). There was no difference in hospitalizations for digestive system diseases between those deployed during the Gulf War and those deployed to the region after the war (HR 0.99, 95% CI 0.94-1.05). Hazard ratios were adjusted for sex, age, marital status, pay grade, ethnicity/race, service branch, occupation, and predeployment hospitalization.