Date amended:
External
Statements of Principles
Current RMA Instruments
 

Reasonable Hypothesis SOP

47 of 2026
  
Changes from previous Instruments

 

ICD Coding
  • ICD-10-AM: F48.8
 
Brief description

Gulf War Illness (GWI) is a chronic condition recognised in veterans who served in the Gulf War Theatre Operations. It is characterised by multiple medically unexplained symptoms affecting several body systems and persisting for at least six consecutive months. 

For the purposes of the SoP, Gulf War Illness is defined using diagnostic criteria derived from the Kansas definition and requires symptoms across multiple symptom domains. The condition is distinct from chronic multisymptom illness, chronic fatigue syndrome, fibromyalgia, post-traumatic stress disorder, and moderate to severe traumatic brain injury. Symptoms may involve fatigue and sleep disturbance, pain, neurological or cognitive difficulties, gastrointestinal symptoms, respiratory symptoms, and skin manifestations. 

Confirming the diagnosis

The diagnosis is clinical and requires assessment against the diagnostic criteria that is consistent with the Kansas definition. Caution should be taken to ensure that symptoms are not better attributed to another condition, though co-morbid mental health conditions are common. 

Clinical assessment and management may include physicians experienced in General Medicine, Psychiatry, Neurology, Rheumatology as well as other specialities, depending on the presenting symptoms. 

Additional diagnoses covered by SOP
  • Nil
 
Conditions not covered by SOP 
  • Chronic fatigue syndrome *
  • Fibromyalgia *
  • Chronic multisymptom illness *
  • Somatic symptom disorder *
  • Post-traumatic stress disorder *
  • Moderate to severe traumatic brain injury *

* Another SOP applies

# Non-SOP condition

Clinical onset

Clinical onset occurs when the diagnostic criteria for Gulf War Illness are first met. This requires the presence of qualifying symptoms across at least three symptom domains, with symptoms persisting for at least six months and not attributable to another medical condition. The condition may develop during or following Gulf War service and typically presents as a chronic disorder with symptoms affecting multiple body systems.  

Clinical worsening

The SoP does not contain clinical worsening factors.