Case definitions

There are several diagnostic criteria for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) that determine how the illness is defined in scientific research and clinical practice.

In biomedical research, the Canadian Consensus Criteria (CCC), published in 2003, are commonly used. In a survey by ME Action the CCC were judged to be the best case definition for research and clinical use, for both specialist and mainstream medical practitioners.

In 2011 an update and modification of the CCC was published by an international panel of ME/CFS experts. This case definition is referred to as the International Consensus Criteria (ICC). Learn more about the CCC and ICC by clicking on one of the links below.