Article Index

Overall differences between the 2011 ME International Consensus Criteria and the 2003 ME/CFS Canadian Consensus Criteria

The 2011 Criteria incorporates much of the new illness research conducted since 2003 and is structured more on an understanding of the systemic pathological processes of the illness. The 2003 Criteria is organized more according to characteristic "symptom clusters".

The 2011 Criteria names the illness solely as ME and drops the name CFS included in the 2003 ME/CFS Criteria. The authors write: "Using 'fatigue' as a name of a disease gives it exclusive emphasis and has been the most confusing and misused criterion."

Another major change in the new ME Criteria is that the 6-month "waiting period" for diagnosis contained in the 2003 criteria (and in the 1994 CDC Criteria) is eliminated. The authors write: "No other disease criteria require that diagnoses be withheld until after the patient has suffered with the affliction for six months."

However, they write: "Notwithstanding, periods of clinical investigation will vary and may be prolonged, diagnosis should be made when the clinician is satisfied that the patient has ME rather than having the diagnosis restricted by a specified time factor."

Two important changes in an understanding of the illness are apparent from the 2011 Criteria. First is a recognition of the body's pathological inability to produce sufficient energy. So the symptoms resulting from the response to exertion or recovery from it are given much more significance and made more explicit in the new Criteria.

Second, the 2011 Criteria reformulates many of the 2003 autonomic and neuroendocrine symptoms under a new, more inclusive, pathological category of energy production/transportation impairments.

The 2011 Criteria overall requires a greater number of minimum symptoms with emphasis on flu-like symptoms, susceptibility to viral infections, genitourinary, gastro-intestinal, and various sensitivities.

The 2003 Criteria, in contrast, distributed its minimum number of required symptoms more broadly among immune, autonomic and neuroendocrine symptom-complexes. It also required fewer minimal total symptoms.

The two definitions vary in how symptoms are categorized or grouped together, as well as in the number or combination of symptoms needed in order for the patient to meet the criteria.