Specific to the Oxford Criteria
- Fatigue present for the last 6 months for more than half the time.
- Illness affects both physical ability and mental functioning
- Fatigue is the principal symptom
- Fatigue out of proportion 'to what you would expect as normal for this level of exertion'
- As judged by the Research Nurse: can the fatigue be distinguished from low mood, sleepiness and low motivation?
Actually, I was surprised by 5, in that it makes some effort to exclude fatigue purely as a result of mood factors.
This is one of the many grey areas and ambiguities in the Oxford Criteria, oceanblue.
For instance, they also state:
"psychiatric disorders (including depressive illness, anxiety disorders, and hyperventilation syndrome) are not reasons for exclusion" [emphasis added]
Therefore, a participant with fatigue and depression can be included, but a participant with fatigue and low mood / low motivation can, apparently, be excluded.
Also of note is the wording of the first question in the operationalised OC:
"Is your fatigue (or a synonym), the principal (main, primary) symptom (e.g. tiredness, lack of energy, weariness, exhaustion)?"
Fatigue or a synonym.
Basically, everyone is welcome except those with demonstrable organic pathology.