Most people with ME/CFS fall into one of four groups:

• Those who manage to return to completely normal health, even though this may take a considerable period of time. The percentage falling into this category is fairly small.
• The majority, who tend to follow a fluctuating pattern with both good and bad periods of health. Relapses or exacerbations are often precipitated by infections, operations, temperature extremes or stressful events.
• A significant minority, who remain severely affected and may require a great deal of practical and social support.
• A few, who show continued deterioration, which is unusual in ME/CFS. When this occurs, a detailed medical assessment is advisable to rule out other possible diagnoses.

Several research studies looking at prognosis in ME/CFS have now been published (Bombardier and Buchwald 1995; Hinds et al 1993; Sharpe et al 1992; Vercoulen et al 1996; Wilson et al 1994). Results from these studies indicate that ME/CFS often becomes a chronic and very disabling illness with complete recovery only occurring in a small minority of cases. The high level of debility and disability associated with ME/CFS often stems from a combination of symptoms such as fatigue, pain, sleep disturbance, cognitive impairment, and, in some cases, an associated depression.

Studies which have examined functional status and quality of life measures (Buchwald et al 1996; Komaroff et al 1996; Schweitzer et al 1995) also confirm that the scale of impairment across a range of physical and mental activities can be just as great or greater than is seen in many other chronic medical conditions.

(taken from ME/CFS/PVFS An exploration of the key clinical issues, prepared for health professionals and The ME Association members by Dr Charles Shepherd MB BS, and Dr Abhijit Chaudhuri DM MD MRCP, Clinical Lecturer in Neurology, Consultant Neurologist, National ME Centre, Harold Wood Hospital, Romford. Essex. RM3 OAR).