The U.S. Institute of Medicine (IOM) has revised the diagnostic criteria for chronic fatigue syndrome (CFS). Patients with systemic exertion intolerance disorder (SEID) must have the following three symptoms:
- As measured by pre-disease levels, the ability to perform occupational, educational, social, and personal tasks is substantially diminished or impaired. This condition has persisted for more than 6 months and is accompanied by fatigue/exhaustion, often profound, that is recent or fixed in onset (i.e., not pre-existing) and not due to previous excessive exertion. Rest does not bring significant improvement.
- Malaise after exertion* .
- Not restful sleep*
At least one of the following two characteristics is also required:
- A. Cognitive impairment* or
- B. Orthostatic intolerance
* Severity and frequency of symptoms should be recorded. The diagnosis of chronic fatigue syndrome should be questioned if symptoms are not present at least half the time with moderate, substantial, or severe intensity. The criteria apply equally to children and adults.
