From: Living With M.E. by Dr. Charles Shepherd, 1999 edition
page 117

Table 6: ME/CFS Disability Scale

0% Fit and well for at least the past three months. No symptoms at rest or following activity. Capable of full time employment.
10% Generally well. No symptoms at rest. Occasional mild symptoms may follow activity. Capable of most kinds of employment.
20% Occasional mild symptoms at rest. More noticeable symptoms following activity. Some restrictions of capabilities which require physical exertion. Able to work full time but difficulty with work that requires physical exertion.
30% Mild symptoms at rest. Limited ability to carry out some tasks which requires physical exertion. May be able to work full time.
40% Mild or moderate symptoms at rest. Variable ability to carry out tasks associated with normal daily living. Unable to work part time in a job involving frequent physical exertion. May be able to work part -time in other types of employment.
50% Mild to moderate symptoms at rest. Moderate to severe exacerbation of symptoms following physical and/or mental exertion. Unable to carry out any strenuous physical tasks. Able to perform light duties or desk work for for several hours a day, provided adequate rest periods are provided.
60% Moderate symptoms at rest. Moderate to severe symptoms following any form of physical or mental exertion. Unable to carry out strenuous duties. Able to carry out light duties/desk work for one to three hours per day, provided adequate rest periods are available. Generally not confined to the house.
70% Moderate to severe symptoms at rest. Severe symptoms follow any physical or mental activity. Able to perform desk work for one to three hours during the day. Often confined to the house and may require wheelchair assistance at times.
80% Moderate to severe symptoms at rest. May only be able to carry out a very minimal range of physical activities relating to personal care (eg. washing, bathing). Frequently unable to leave the house and may be confined to wheelchair or bed for much of the day. Unable to concentrate for more than short periods of time.
90% Severe symptoms at rest. Bedridden and housebound for much of the time. Experiences considerable difficulties with many aspects of personal care. Marked problems with mental functioning (eg. memory, concentration). Requires a great deal of practical support.
100% Severe symptoms on a continual basis. Bedridden and incapable of living independently. Requires a great deal of practical social support.