The result was a "clinically based descriptive definition using correlated symptoms" in six symptom groups: fatigue and sleep problems, pain, neurologic and mood, gastrointestinal, respiratory symptoms, and skin (dermatologic) symptoms.To meet the "Kansas" case definition, a veteran of the 1990–91 Gulf War must have symptoms in at least three of the six symptom domains, which during the survey were scored based on severity ("severity"). Symptom onset must have developed during or after deploying to the 1990–91 Gulf War theatre of operations ("onset") and must have been present in the year before interview ("duration"). Participants were excluded if they had a diagnosis of or were being treated for any of several conditions that might otherwise explain their symptoms ("exclusionary criteria"), including cancer, diabetes, heart disease, chronic infectious disease, lupus, multiple sclerosis, stroke, or any serious psychiatric condition.Applying the Kansas case definition to the original Kansas study cohort resulted in a prevalence of Gulf War illness of 34.2% in Gulf War veterans and 8.3% in nondeployed Gulf War era veterans, or an excess rate of GWI of 26.3% in Gulf War veterans. CDC definition
Also in 1998, a study published by Dr. Keiji Fukuda under the auspices of the U.S. Centers for Disease Control and Prevention (CDC) examined chronic multisymptom illness through a cross-sectional survey of 3,675 ill and healthy U.S. Air Force veterans of the 1990–91 Gulf War, including from a Pennsylvania-based Air National Guard unit and three comparison Air Force units.
The health consequences of chemical exposures in the GW and other conflicts have been called "toxic wounds" by veterans. This type of injury requires further study and concentrated treatment research efforts that may also benefit other occupational groups with similar exposure-related illnesses." Earlier considered potential causes
Depleted uranium
Depleted uranium (DU) was widely used in tank kinetic energy penetrator and autocannon rounds for the first time ever during the Gulf War and has been suggested as a possible cause of Gulf War syndrome. A 2008 review by the U.S. Department of Veterans Affairs found no association between DU exposure and multisymptom illness, concluding that "exposure to DU munitions is not likely a primary cause of Gulf War illness". However, there are suggestions that long-term exposure to high doses of DU may cause other health problems unrelated to GWI.More recent medical literature reviews disagree, stating for example that, "the number of Gulf War veterans who developed the Gulf War syndrome following exposure to high quantities of DU has risen to about one-third of the 800,000 U.S. forces deployed," with 25,000 of those having had a premature death. Since 2011, US combat veterans may claim disability compensation for health problems related to exposure to depleted uranium. The Veterans Administration decides these claims on a case-by-case basis.