Review Of 6 ME/CFS Ability And Severity Scales

A (dis)ability scale, severity scale or performance status is an attempt to quantify patients’ general well-being. They can be used to classify patients as to their functional impairment, to compare the effectiveness of therapies and to track health over time.

A. Requirements

During the 8 years since my diagnosis with CFS I have experienced a remission and a relapse of which I haven’t recovered yet. The remission from 40% to 80% on one of the scales mentioned below took almost 3 years. At 80% I could work 4 days a week, exercise and participate in an online course. What I am looking for in a scale is an easier way to communicate with my doctor and medical adviser. Instead of summing up all the things I can and can’t do, and the consequences of not respecting my limitations, I would simply be able the say, “Hi doc, I am at 40%.”

What are the requirements for a disability, ability, or severity scale for ME/CFS?

• easy to use
• cognitive and physical disabilities
• linear curve
• in sickness and in health.

1. Easy To Use

All you should need is a piece of paper with the scale: a table with 2 columns; the rating and the criteria or description for the rating. No need for blood tests, measuring blood pressure, a heart monitor, or a calculator. ME/CFS can cause cognitive problems so you should make it as easy to use as possible.

2. Cognitive and Physical Disabilities

A scale for ME/CFS must not only take into account the physical symptoms like pain, fatigue, and malaise, but also the neurological symptoms like loss of cognitive abilities and brainfog. This disease can affect people in a different ways and the scale should be able to cope with that.

3. Linear Curve

Most ME/CFS scales you will find are represented by a table, but I tried to visualize them on a chart. It wasn’t easy but I found real mathematical functions that can be used to visualize the scales: linear, exponential, parabolic and sigmoid. The horizontal axis on the chart represents the rating from 0 to 100% and the vertical axis your abilities or health from bedridden to normal.

A linear curve is easiest to understand. This means that if you make a bit of progress health wise your rating should also increase by a bit. If you experience a minor or major relapse after an infection then the rating should decrease correspondingly.  Simple, straightforward and easy to visualize.

A parabolic curve represents a model where at first the rating increases slower than any improvements health wise, it slowly catches up and on the second half of the curve the rating starts to increase faster and faster for any given improvement in your abilities. A parabolic curve means you give more attention to disabilities than to abilities.

An exponential curve is almost a parabolic curve to the extreme. The rating increases from 0 to 70-80% with only marginal improvements to your health and quality of life. Then in the last 20-30% you go from still very sick to full recovery.

A sigmoid curve was the most difficult one to match. Most part the relationship between rating and health is more or less is represented by linear or parabolic curve, but in the middle a small change in rating is matched to a huge change in your abilities.

4. In Sickness and in Health

A scale that goes from bedridden to very sick is insufficient and depressing. The range must be from bedridden to a more or less normal life. The ideal scale pays as much attention to what you can do as to what you can’t do. The rating must be realistic; 50% should mean that you are halfway there.  Not that you are ready to work half-time because you will still need energy for taking care of yourself (showering, cooking, shopping). As soon as you reach 60% it should be realistic to start looking for a part-time job, study, or volunteer work. If you post-pone this to 80% you focus too much on being sick. Is a glass half empty or half full?

B. Disability Scales

1. Karnofsky Performance Scale

The Karnofsky Performance (Status) Scale, Rating Scale, or Score is an assessment tool used to assist clinicians and caretakers in measuring a patient’s ability to carry out activities of daily living. Originally intended for cancer patients, it is now used for other diseases like HIV and  as criteria for entrance into a clinical trial.

This scale is a good example of an exponential curve: the scale runs from 0 to 100% where 0% is death and 100% is healthy, but only at 70% are you capable of starting to care for yourself. This scale focuses a lot more on disabilities than on abilities. There is no way to express cognitive abilities and to make a distinction between capable of part-time, half-time or full-time work.

2. Martin Lerner’s Energy Index Point Score ®

It wasn’t easy to find a mathematical function to match the EIPS by Dr. Martin Lerner. The best fit for this scale is a sigmoid curve. The EIPS scale goes from 0 (bedridden) to 10 (normal). From 0 to 4 and from 5 to 10 it can be visualized by a more or less linear curve or slightly parabolic curve, but the difference between the ratings 4 and 5 is huge.

4: Out of bed sitting, standing, walking 4 – 6 hours per day
5: Perform with difficulty sedentary job 40 hours a week, daily naps

How do you go from being out of bed for 4-6 hours to a full-time job? In my experience the best way to make progress is to start with a part-time job or study when you are ready for it and gradually increase the hours. Finding a full-time job where napping is allowed is also not very realistic. When you start to work again you may never forget that you will still need some spare energy for commuting, shopping, cooking, … Spending all your energy at work, crashing when you get home every day, and dragging yourself back to work the next day isn’t a sustainable approach.
The downloadable document with the scale is littered with the registered trademark symbol ®, but could really use a reality check. According to Dr. Lerner you must first go for a full-time job and only afterwards you can try to add some light housekeeping to your schedule. Sounds like it is made up by a man.

3. David Bell’s CFS Severity Scale

Dr. David Bell is a well respected doctor in the ME/CFS community and with good reason. His scale is easy to use, goes from bedridden to healthy, and of all the scales reviewed it provides the closest match to a linear curve. The scale leaves some room for interpretation which is good because it must be used by men and women, by white color and blue collar workers, by adults, children, and students, …

The description of the 40% rating for the CFS Severity Scale:

Moderate symptoms at rest. Moderate to severe symptoms with exercise or activity; overall activity level reduced to 50%-70% of expected. Not confined to house. Unable to perform strenuous duties; able to perform light duty or desk work 3-4 hours a day, but requires rest periods.

4. The Hummingbirds’ Foundation for M.E. 3 Part Ability and Severity Scale

The approach by the Hummingbirds’ Foundation for M.E. (HFME) is unique because they provide separate scales for physical ability, cognitive ability, and symptom severity. This sounded good because physical and cognitive abilities can be affected in different ways until I tried to rate my physical abilities. Below you will find the description for 50%:

Overall activity level reduced to around 30% of expected. May be unable to walk without support much beyond 100/200m, a walking stick or wheelchair may be used to travel longer distances. Several hours of desk work may be possible each day if requirements for quiet and resting are met. Physically undemanding social activities are possible.

Unable to walk without support beyond 200m represents a reduction in activity level to 30%! You’ve got to be kidding me! This would mean that a healthy person can only walk 600-700m! This sounds more like a 3% activity level to me.

The description of the 50% rating for the cognitive ability scale:

Cognitive functioning is reduced to around 30% of expected. Unable to perform mentally challenging tasks, but able to complete simpler cognitive tasks (study or work) for 3 – 4 hours a day (or perhaps longer at a lower quality level) if requirements for quiet and resting are met. Concentration and cognitive ability are significantly affected. Following the plots of TV shows or books may be difficult. Non-mentally challenging social activities possible on a limited basis.

If you are capable of doing simpler cognitive tasks, incl. study, for 3-4 hours a day even assuming you do them in 1 hour shifts followed by resting, surely you must be capable of following the plots of TV shows and series. If you have done 4 hours of work or study and after that are unable to follow a game show like a quiz, that is normal because that would be your fifth hour of cognitive challenges. I also thought that the whole idea of study is to provide a mentally challenging task. I wouldn’t consider study to be a simple cognitive task.

The description of the 50% rating for the symptom severity scale:

Moderate symptoms (6 or 7/10) at rest. There is moderate pain and/or sensations of illness/dysfunction throughout the body and brain for significant periods of the day. Increasing moderate (and occasionally severe – 8/10) symptoms for several hours, days or weeks following physical or mental activity beyond the persons limits which may persist for hours, days or a week or more afterward.

It’s clearly that this scale needs some editing. Apparently it doesn’t matter for your rating if the moderate to severe pain and symptoms persist for several hours to a week or more afterwards. I don’t agree with this point of view. If you overdo it, and the moderate pain disappears after a couple of hours, you have a light case of ME/CFS. If you overdo it and you are still in pain after a week or more, you have a severe case of ME/CFS.

The idea behind the multi-part scale is good, but the execution by HFME is a failure. I was unable to rate myself on the scales because the descriptions contain contradictory information.
To visualize these scales you would have the use a parabolic curve. The focus on severe cases which distorts the curve is intentional by HFME. The Hummingbirds’ Foundation for M.E. even offers 2 sets of the 3-part ability and severity scales. One for severely affected patients and one for mildly affected patients, both ranging from bedridden to normal life.

5. Charles Shepherd’s CFS Disability Scale

The main difference between this scale and the others is that this one is upside down; 100% means bedridden and 0% means healthy. This doesn’t feel good, if my rating increases with 10% I want it to be an improvement not a worsening of my condition. There isn’t that much difference with Dr. David Bell’s scale, but it is less specific. To visualize this scale you would need a slightly parabolic curve.
Below you will find the description for 60% (moderate symptoms at rest) (remember it is upside down):

Moderate to severe symptoms following any form of physical or mental exertion. Unable to carry out any strenuous duties. Able to carry out light duties/deskwork for one to three hours per day. Generally not confined to the house.

6. AYME Functional Ability Scale

This ability scale by the Association of Young People with ME is intended for children, young people and students. To visualize this scale you would need an parabolic or exponential curve. The description for 60% on a scale from 0% (bedridden) to 100% (full recovery):

Mild to moderate symptoms at rest. Increasing symptoms following physical or mental activity. Daily activity very limited. Study with others or work outside the home very difficult unless additional support is available, e.g. use of a wheelchair/quiet room for a rest period. Short (1-2 hours) daily home study/work may be possible on good days. Quiet, non-active social life possible.

According to this scale at 60% the best you can hope for is 1-2 hours of study at home and you will need a wheelchair to go outside. This just won’t do. To visualize this scale you would need a parabolic or even an exponential curve.

C. My Scores

Scale	Rating
Karnofsky	70%
EIPS	4
Dr. David Bell	40%
HFME Physical	?
HFME Cognitive	?
HFME Symptoms	?
Charles Shepherd	60%
AYME	70%

PS: I rated myself based on my condition in December. The long winter and a throat/nose/ear/eye-infection would decrease my rating by at least 10% right now, but I am hoping this is just a temporary setback. I am already recovering, slowly.

D. Conclusion

I had the impression while reviewing these scales that the authors started at 0% or bedridden and wanted to describe how debilitating ME/CFS and how little patients can do and then all of a sudden they find themselves at 70% and there is only 30% left to a full recovery.

I recommend to use Dr. David Bell’s CFS Severity Scale to express the severity of your case and to document any changes for better or for worse. I find it the most easiest scale to use, it’s versatile and intuitive.
The scale by Dr David Bell still leaves some room for interpretation. What is light work? What does “overall activity level reduced to 50-70% of expected” mean? It depends of course  on your life before you had ME/CFS. The reduction to 50-70% of activity level will mean something differently if you were a really active person or a couch potato before you became sick. I will clarify what the ratings on David Bell’s CFS Severity Scale mean to me personally:

40%:

• 3-4 hours throughout the day for cognitive tasks like writing this article, experiment with computer configurations, and maybe even modify some small, existing scripts (programming) (never longer than 1 hour without resting)
• unable to program or write code from the ground up or to understand large pieces of code
• cycle 18 km at an average heart rate of 115 bpm (1 hour)
• go to the gym for 15 minutes of weightlifting (not on same day as cycling)
• do all of my own shopping

80% (Spring 2007 at the peak of my remission):

• work 4 days per week as a webdeveloper and system engineer (I really needed my Wednesday off)
• able to go to the gym for 15-20 minutes of weightlifting or cycle maximum 20 km after work (alternating days)
• able to attend an online programming course after work, but had to leave the study and exercises for my days off
• able to cycle 25-35 km or swim 1000-1500 m on my days off (Wednesday & weekend)
• do all of my own shopping
• was looking for an apartment to live on my own again
• for any work-related after-hours activities like a barbecue I had to take the afternoon off to sleep and then I was still the first to go home

ME/CFS is a so called invisible illness. Meaning it is hard to determine not only if you are sick but also how sick you really are. I discovered the (dis)ability scales a couple of months ago and I wondered why not one of the doctors, specialists, and even psychiatrists and psychologist at the CFS Reference Center ever mentioned, let alone used, one of these in the past 8 years.
There are probably thousands of publications on the effect of GET and CBT on ME/CFS patients (positive and negative), but if you can’t measure it with a blood test and you don’t mention the use of a (dis)ability scale how did they quantify the changes?

E. References

• AETC – Karnofsky Performance Scale
• Not Done Living – Scales
• The Hummingbirds’ Foundation for M.E. 3 Part Ability and Severity Scale
• AYME – Functional Ability Scale
• Treatment Center for CFS – Energy index Point Score
• CFIDS Association of America – Dr Bell’s Disability Scale [PDF]

Health is a state of complete physical, mental and social well-being, and not merely the absence of disease or infirmity.

World Health Organization, 1948

Tagged as: ability, Awareness, disability, scale