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Canadian Consensus for ME/CFS: A Clinical Case Definition & Guidelines for Medical Practitioners

We consider these guidelines provide the best contemporary definition of the illness. It was developed for clinical practice and was compiled by physicians who have seen over 20,000 patients. We believe that using these Guidelines it is harder for people with “chronic fatigue” to be misdiagnosed with ME/CFS. Below are the comments of some experts around the world about this document:


"Our comparison study examined differences between patients meeting the Canadian clinical and the Fukuda et al. criteria for ME/CFS, with people who had chronically fatiguing illness explained by a psychiatric condition. The Canadian Clinical Criteria selected patients with more physical functional impairment, more fatigue/weakness, neurocognitive and neurological symptoms and had more variables that significantly differentiated them from the psychiatric comparison group than did the Fukuda et al. criteria. The findings do suggest that the Canadian criteria point to the potential utility in designating post-exertional malaise and fatigue, sleep dysfunction, pain, clinical neurocognitive, and clinical autonomic/neuroimmunoendocrine symptoms as major criteria. The selection of diagnostic signs and symptoms has major implications for which individuals are diagnosed with ME/CFS and how seriously the illness is viewed by health care providers, disability insurers, rehabilitation planners, and patients and their families and friends. I hope the results of this comparison study will encourage more physicians to use the Canadian Clinical Criteria".


Leonard A. Jason, Ph D

Director: Center for Community Research, DePaul University, Chicago IL

Board of Directors: American Association for Chronic Fatigue Syndrome

"The Canadian Clinical Case Definition has brilliantly rewritten the guidelines to capture, at last, what ME/CFS is really all about. It is not that patients are fatigued. Healthy people get fatigued. Rather the definition specifically selects patients who worsen with exercise. This takes the emphasis away from the subjective sensation of “fatigue” and forces one to clearly describe the connection between fatigue and activity. This also embraces mental fatigue (loss of cognitive function and alertness) as well as physical fatigue (lack of energy and strength, often felt in the muscles). The patient must become symptomatically ill after exercise and must also have evidence of neurocognitive, neuroendocrine, dysautonomic (e.g. orthostatic intolerance), and immune malfunction. The Adelaide Forum agreed to "...unanimously embrace the Canadian Case definition..." with a strong recommendation that it also be taken up by ME/CFS societies. (Except from the review of the Adelaide Forum, Australia, 2005)".


Michael Barratt, MBBS, FRCPA

Adelaide, Australia

"In my opinion, and in the opinions of the other doctors at the Environmental Health Clinic, the ME/CFS Consensus Document is extremely practical and useful. We have used it repeatedly in helping to develop comprehensive individual treatment plans in collaboration with patients. At the behest of the Ontario College of Family Physicians' (OCFP) Environmental Health Committee, and with approval of the publisher, the consensus diagnostic checklists were posted on the OCFP website. We also use the diagnostic criteria, checklists, and treatment suggestions as teaching tools in the OCFP's Environmental Health Day at their Annual Scientific Assembly".


Lynn Marshall, MD, FAAEM, FRSM

Medical Director: Environmental Health Clinic,

Sunnybrook & Women's College Health Sciences Centre

Member: Environmental Health Committee, Ontario College of Family Physicians

Lecturer: University of Toronto Department of Family and Community Medicine

Assistant Professor of Family Medicine: Northern Ontario School of Medicine

The Canadian Consensus Document on ME/CFS is currently distributed in the UK by Invest in ME. If you want to access to this document on the internet click on the picture below. It will direct you to Invest in ME website (© Copyright 2005 by Carruthers B.M. and van de Sande M.I. All rights reserved). If you would like a hard copy of this document, please email Invest in ME to:

Please click on the button below to download the Canadian Consensus Document.

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