Clinical diagnosis of<unk> <unk>  illness has been complicated by multiple case definitions. In 2014, the National Academy of Sciences Institute of Medicine (IOM)—contracted by the U.S. Department of Veterans Affairs for the task—released a report concluding that the creation of a new case definition for chronic multisymptom illness in<unk> <unk>  veterans was not possible because of insufficient evidence in published studies regarding its onset, duration, severity, frequency of symptoms, exclusionary criteria, and laboratory findings. Instead, the report recommended the use of two case definitions, the "Kansas" definition and the "Centers for Disease Control and Prevention (CDC)" definition, noting: "There is a set of symptoms (fatigue, pain, neurocognitive) that are reported in all the studies that have been reviewed. The CDC definition captures those three symptoms; the Kansas definition also captures them, but it also includes the symptoms reported most frequently by<unk> <unk>  veterans." The Kansas case definition is more specific and may be more applicable for research settings, while the CDC case definition is more broad and may be more applicable for clinical settings. Classification Medical ailments associated with service in the 1990–1991<unk> <unk>  have been recognized by both the U.S. Department of Defense and the U.S. Department of Veterans Affairs. Before 1998, the terms<unk> ,<unk> <unk>  veterans' illness, unexplained illness, and undiagnosed illness were used interchangeably to describe chronic unexplained symptoms in veterans of the 1991<unk> <unk> . The term chronic multisymptom illness (CMI) was first used following publication of a 1998 study describing chronic unexplained symptoms in Air Force veterans of the 1991<unk> <unk> . In a 2014 report contracted by the U.S. Department of Veterans Affairs, the National Academy of Sciences Institute of Medicine recommended the use the term<unk> <unk>  illness rather than chronic multisymptom illness. Since that time, relevant publications by the National Academy of Science and the U.S. Department of Defense have used only the term<unk> <unk>  illness (GWI). The U.S. Department of Veterans Affairs (VA) confusingly still uses an array of both old and new terminology for<unk> <unk>  illness. VA's specialty clinical evaluation<unk>  Related Illness and Injury Study Centers (WRIISCs) use the recommended term<unk> <unk>  illness, as do VA's Office of Research and Development (VA-ORD) and many recent VA research publications. However, VA's Public Health website still uses<unk> <unk>  veterans' medically unexplained illnesses, chronic multi-symptom illness (CMI), and undiagnosed illnesses, but explains that VA doesn't use the term<unk>  because of varying symptoms. The Veterans Health Administration (VHA) originally classified individuals with related ailments believed to be connected to their service in the Persian<unk>  a special non-ICD-9 code DX111, as well as ICD-9 code V65.5. Kansas definition In 1998, the State of Kansas Persian<unk>  Veterans Health Initiative sponsored an epidemiological survey led by Dr. Lea Steele of deployment-related symptoms in 2,030<unk> <unk>  veterans. 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<unk> <unk>  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<unk> <unk>  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<unk> <unk>  illness of 34.2% in<unk> <unk>  veterans and 8.3% in nondeployed<unk> <unk>  era veterans, or an excess rate of GWI of 26.3% in<unk> <unk>  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<unk> <unk> , including from a Pennsylvania-based Air National Guard unit and three comparison Air Force units. The CDC case definition was derived from clinical data and statistical analyses. The result was a symptom-category approach to a case definition, with three symptom categories: fatigue, mood–cognition, and musculoskeletal. To meet the case definition, the veteran of the 1990–91<unk> <unk>  must have symptoms in two of the three categories and have experienced the illness for six months or longer ("duration"). The original study also including a determination of severity of symptoms ("severity"). "Severe cases were identified if at least one symptom in each of the required categories was rated as severe. Of 1,155 participating<unk> <unk>  veterans, 6% had severe CMI, and 39% had mild to moderate CMI; of the 2,520 nondeployed era veterans Of 1,155 participating<unk> <unk>  veterans, 6% had severe CMI, and 39% had mild to moderate CMI; of the 2,520 nondeployed era veterans, 0.7% had severe and 14% had mild to moderate CMI."
Gulf War syndrome
SAHA syndrome
Toxic shock syndrome
Primrose syndrome
Proteus syndrome
Systemic inflammatory response syndrome
SUNCT syndrome
Severe fever with thrombocytopenia syndrome