Evaluating Claims Involving Chronic Fatigue Syndrome (CFS)
CFS is a systemic disorder consisting of a complex of symptoms that may vary in frequency, duration, and severity. In 1994, an international panel convened by the Centers for Disease Control and Prevention (CDC) developed a case definition for CFS that serves as an identification tool and research definition.  In 2003, an expert subcommittee of Health Canada, the Canadian health agency, convened a consensus workshop that developed a clinical case definition for CFS, known as the Canadian Consensus Criteria (CCC).  In 2011, a private international group developed guidelines, known as the International Consensus Criteria (ICC),  for diagnosing myalgic encephalomyelitis (ME).  Members of this international group and other medical experts consider ME to be a subtype of CFS.  We adapted the CDC criteria, and to some extent the CCC and ICC, when we formulated the criteria in this SSR. 
We consider a person to be “disabled”  if he or she is unable to engage in any substantial gainful activity by reason of any medically determinable physical or mental impairment(s)  which can be expected to result in death or which has lasted or can be expected to last for a continuous period of not less than 12 months. We require that an MDI result from anatomical, physiological, or psychological abnormalities, as shown by medically acceptable clinical and laboratory diagnostic techniques.  The Act and our regulations further require that the impairment be established by medical evidence that consists of signs, symptoms, and laboratory findings; therefore, a claimant may not be found disabled on the basis of a person’s statement of symptoms alone.  In this SSR, we explain that CFS, when accompanied by appropriate medical signs or laboratory findings, is an MDI that can be the basis for a finding of “disability.” We also explain how we evaluate CFS claims.