Chronic fatigue syndrome
For CFS, a modification to the alphabetic index was made, effective on October 1, 1991, to direct users to code 780.7, Malaise and fatigue, the same code used to identify cases of postviral syndrome. In 1998, a new five-digit code included 780.71, Chronic fatigue syndrome, consistent with the WHO version of ICD-9. Chronic fatigue syndrome is classified in tabular list: "Symptoms, Signs and Ill-Defined Conditions," under the sub-heading of "General Symptoms".