Two studies assessed mortality in UK Gulf War veterans from diseases of the digestive system (DASA, 2009; Macfarlane et al., 2005). Macfarlane et al. (2005) assessed mortality of the UK Gulf War (51,753) and era (50,808) veteran cohorts from April 1, 1991, to June 30, 2004. Based on data from the National Health Service, the Gulf War veterans experienced fewer deaths from digestive diseases than the era cohort (mortality rate ratio 0.77, 95% CI 0.40-1.46), adjusted for age. The UK Defence Analytical Services Agency (DASA) published summary statistics on causes of deaths in Gulf War veterans between April 1, 1991, and December 31, 2007 (DASA, 2009). Mortality rates for the 53,409 Gulf War veterans were compared with the 53,143 era veterans. The adjusted mortality rate ratio for diseases of the digestive system was 0.71 (95% CI 0.46-1.11).
Finally, one study is notable for using specific Rome III criteria for the diagnosis of irritable bowel syndrome in war-time situations. Tuteja et al. (2008) studied 247 Gulf War deployed and nondeployed veterans from Salt Lake City who were in the reserves or National Guard and deployed between 1990-1991. It was found that there was an increased reporting of IBS from before deployment (5.8%) to during deployment (38.9%; p = 0.03) and this continued after deployment 18 years later (33.6%). Similar significant findings were seen with symptoms of diarrhea, constipation, and bloating. Furthermore, a history of an enteric infection was a risk factor for developing IBS (OR 3.6, 95% CI 1.9-6.9) now called postinfectious IBS. These data are presently available in abstract form only, and therefore this study is considered to be secondary.
There were many reports of gastrointestinal disturbances in Gulf War deployed veterans and the symptoms have persisted during the 19 years since the war. Notably all studies are in the direction favoring a greater prevalence of various GI symptoms and primarily functional GI disorders including IBS and dyspepsia.
Several of the papers attempted to link the symptoms to various exposures including side effects from nerve agent prophylaxis, using contaminated water, and burning of animal waste, but support from this is also limited and nonconfirmatory. More compelling is the emerging evidence for exposure to enteric pathogens during deployment leading to the development of postinfectious IBS. These data have been strengthened in recent years as a result of several lines of evidence:
The incidence of acquiring an acute gastroenteritis among deployed veterans is higher than nondeployed veterans, over 50% in some series (IOM, 2007).
Deployed veterans or other individuals experiencing war trauma who are exposed to an infectious gastroenteritis are at greater risk to be later diagnosed with IBS (Pulling et al., 2008; Riddle et al., 2009; Tuteja et al., 2008).
Deployed veterans that have IBS symptoms have increased microscopic inflammatory changes in the bowel mucosa which can result from prior mucosal infection (Lang and Saylor, 1995; Sostek et al., 1996).
Microscopic inflammation in IBS is associated with increased cytokine activity and mast cell degranulation that produces visceral hypersensitivity and abdominal pain (Barbara et al., 2004; Chadwick et al., 2002).