Table 1 The PS score for evaluating severity of fatigue in ME/CFS patients

0: The subject is able to have a normal social life without fatigue and to function without restrictions

1: The subject is able to have a normal social life and work, but often feels fatigue

2: The subject is able to have a normal social life and work, but often needs rest due to general malaise

3: The subject is unable to engage in social life or work for several days a month because of general malaise and needs to rest at home

4: The subject is unable to engage in social life or work for several days a week because of general malaise and needs to rest at home

5: The subject is unable to engage in normal social life or work. The subject is able to do light work, but needs to rest at home several days a week

6: Light work is possible on good days, but the subject rests at home more than 50% of the week

7: The subject is able to take care of him/herself and does not need assistance, but normal social activities and light work are not possible

8: The subject is able to take care of him/herself to a certain extent, but often needs assistance and stays in bed more than 50% of the time during the day

9: The subject is unable to take care of him/herself at all, requires constant assistance, and stays in bed all day