Author Topic: ? Chalder Fatigue Scale ?  (Read 3273 times)

jace

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? Chalder Fatigue Scale ?
« on: February 22, 2011, 02:00:14 PM »
I have read the Chalder Fatigue Scale, and other papers on it, and I am still not clear on an important fact.

How darn big is it?  After researching, I was under the impression that it worked on a scale of 100, but I have read on this forum that it is a 33 point scale.  Which is true?
Quote
The validation coefficients for the fatigue scale, using an arbitrary cut off score of 3/4 and the item on the CIS-R were: sensitivity 75.5 and specificity 74.5.
Quote
A list of 14 questions were generated by various experts..   three items were eliminated.... leaving 11 items



Nowhere in the paper can I find a reference to 33 points.
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Mithriel

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Re: ? Chalder Fatigue Scale ?
« Reply #1 on: February 22, 2011, 05:28:44 PM »
The statistics are beyond me and I don't want to hijack the thread but can someone explain how this scale can possibly work for ME or CFS.

The questions ask things like, "How much more fatigued are you than usual?"

My answer would have to be "not at all" even if I take fatigue to mean the crushing exhaustion and malaise with the slightest effort that is a symptom of ME.

My "usual" level fo activity is very low and this scale does not seem to pick it up.

Am I missing something?

Mithriel

subtr4ct

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Re: ? Chalder Fatigue Scale ?
« Reply #2 on: February 22, 2011, 05:33:27 PM »
I have some experience with principal components analysis.  If you could point me towards the full paper, I might be able to help
Disclaimer: I am not a medical doctor.  This post is not medical advice.  Consult your physician before taking any action.

Tango

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rebecca

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Re: ? Chalder Fatigue Scale ?
« Reply #4 on: February 22, 2011, 05:49:11 PM »
I can't comment on this scale, but I do know that the Bell Disability Scale is the only fatigue scale that has been validated for ME/CFS by an objective measure, ATP output.

Dr. Myhill's 2009 study of mitochondrial function in CFS found a direct relationship between ATP output and Bell score:

Quote
With the consent of each of 71 patients and 53 normal, healthy controls the 5 factors have been collated and compared with the Bell Ability Scale. The individual numerical factors show that patients have different combinations of biochemical lesions. When the factors are combined, a remarkable correlation is observed between the degree of mitochondrial dysfunction and the severity of illness (P<0.001).

subtr4ct

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Re: ? Chalder Fatigue Scale ?
« Reply #5 on: February 22, 2011, 07:36:25 PM »
I have read the Chalder Fatigue Scale, and other papers on it, and I am still not clear on an important fact.

How darn big is it?  After researching, I was under the impression that it worked on a scale of 100, but I have read on this forum that it is a 33 point scale.  Which is true?


Nowhere in the paper can I find a reference to 33 points.

The paper is very terse, and I agree that they have not adequately explained how the "Fatigue Scale" is calculated.   Based on the fact that they report not assigning weights to the qualitative responses, I am guessing that the reference to 33 points would come from assigning the following "points" to the 11 questions that were not eliminated from the original set of 14.

0 -- "better than usual"
1 -- "no more than usual"
2 -- "worse than usual"
3 -- "much worse than usual"

Total possible points = 11*3 = 33.  This is just my best guess, though.

Within the paper, however, they make reference to a cutoff value for the Fatigue Scale on the unit interval (i.e., a score between zero and one).  Perhaps they obtain the zero-to-one score (which could of course be scaled to a 0-100 score) by dividing total points by 33?  Again just a guess given the incomplete description of the methods.  They ultimately decide that 0.75 (i.e., more than 24 points?) provides the optimal balance between sensitivity and specificity in correctly predicting how respondent would be categorized (fatigued or not) by some other questionnaire ("Revised Clinical Interview Schedule", fatigue question(s)).

Mithriel raises an excellent point in that the "usual" state of affairs is a moving target as one's fatigue duration extends.

Also, they conclude that there are two significant* dimensions to fatigue (two significant principal components to their 14-dimensional data; two significant eigenvalues in the response covariance matrix (where responses have been quantified as I guessed above?)), but they apparently proceed nonetheless to use the single-dimensional Fatigue Scale score for categorizing patients.
Disclaimer: I am not a medical doctor.  This post is not medical advice.  Consult your physician before taking any action.

slayadragon

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Re: ? Chalder Fatigue Scale ?
« Reply #6 on: August 31, 2011, 02:58:33 PM »
Has anyone learned more about the Chalder Fatigue Score?  I want to know for sure what the items are and what the 33-point scale is.

This is a key measure in the PACE study, so it's important to understand it.

Thanks much for any help folks can provide.

Best,

Lisa

Tango

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Re: ? Chalder Fatigue Scale ?
« Reply #7 on: August 31, 2011, 03:01:11 PM »
I put what I could find here http://www.mecfsforums.com/wiki/Chalder_fatigue_questionnaire

I don't think there are mistakes, but I'm not hot on this subjective rubbish.   :D
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slayadragon

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Re: ? Chalder Fatigue Scale ?
« Reply #8 on: September 02, 2011, 02:54:08 PM »
Amazing how hard it is to find out info about the primary dependent variable in that study.

Based on reading Chalder 1993 paper, and some other papers, this is what I think it is. 

1. Do you have problems with tiredness?
2. Do you need to rest more?
3. Do you feel sleepy or drowsy?
4. Do you have problems starting things?
5. Are you lacking in energy?
6. Do you have less strength in your muscles?
7. Do you feel weak?
8. Do you have difficulty concentrating?
9. Do you have problems thinking clearly?
10. Do you make slips of the tongue when speaking?
11. How is your memory?

0 - Less than usual
1 - No more than usual
2 - More than usual
3 - Much more than usual


But I'm a little perplexed because someone on PR just listed the following, excluding "thinking clearly" and including "difficult to find the right word"

Chalder Fatigue Scale - contains 11 questions

• Do you have problems with tiredness?
• Do you need to rest more?
• Do you feel sleepy or drowsy?
• Do you lack energy?
• Do you have trouble starting things?
• Do your muscles have less strength?
• Do you feel weak?
• Do you have difficulty concentrating”
• Do you find it more difficult to find the correct word?
• Do you make slips of the tongue when speaking?
• How is your memory?

http://forums.phoenixrising.me/showthread.php?13096-Please-help-evaluate-the-Chalder-Fatigue-Scale


Does anybody know for sure?  I'm writing a critique of the PACE paper and want to make sure I get this right.

Thanks, Lisa
« Last Edit: September 02, 2011, 02:56:29 PM by slayadragon »

floydguy

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Re: ? Chalder Fatigue Scale ?
« Reply #9 on: September 02, 2011, 03:37:33 PM »
I wonder if the best way to respond to this crap is portray Chalder et al as crackpot "scientists" who only care about lining their pockets with endless research funding.  Why is it that real scientists don't stand up and lambaste such crap?  Is it professional courtesy or is there something else going on?

peggy-sue

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Re: ? Chalder Fatigue Scale ?
« Reply #10 on: September 02, 2011, 04:07:43 PM »
I do think there's a certain amount of "professional courtesey" (good old boys in the club)  going on.

But there may be other things too.
I did a BSc Hons degree in psychology - in an ARTS department. (I was in the Faculty of Science.)
I studied Science subjects to the end of second year - my psychology modules were "counted" by the Science Faculty.
However, when I started psychology lectures, I discovered they wouldn't know what real science was if it jumed out of the gutter and bit them on the ankle.
They took a top-down and dualistic approach to the subject - and tons of time was wasted studying 19th century stuff - from the basics - including replications of stuff debunked for decades!

I was furious and had a whole load of arguements with lecturers and professors over it, eventually trying to get to see the Dean of the Science faculty to complain about the complete lack of real or good science in the BSc. I was being awarded.
I got fobbed off and fobbed of, eventually only getting as far as the secretary - who unfirtunatley was a so-called BSc in the pseudoscience of Cognitive psychology. So I got more fobbed off by him.

However, what I did manage to glean was:
Arts Faculty students brought in £3000 worth of fees each pa.
Science Faculty students brought in £7000 worth of fees each pa.

And the University, who has the power to call your degree what it feels like calling it, decided that their integrity was worth less than the extra dosh brought in by shoving roughly 16 students per year from Science into the Arts Faculty and pocketing the extra cash.
An extra £64000 for each year pa.

But at least I'm properly qualified to say that Cognitive Psychology is a load of dualistic pseudoscience
- they don't understand methodology,
- they haven't a clue about confounding variables
- they can't even get to grips with how many tails their hypotheses have

and they never studied any basic science in the first place.


It's shocking.


A fortune teller is put under a curse. The curse makes her very frail, makes her skin rough and blistered and gives her terrible breath.
She's a super-calloused fragile mystic, hexed by halitosis.

Dolphin

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Re: ? Chalder Fatigue Scale ?
« Reply #11 on: September 02, 2011, 10:18:01 PM »
The paper is very terse, and I agree that they have not adequately explained how the "Fatigue Scale" is calculated.   Based on the fact that they report not assigning weights to the qualitative responses, I am guessing that the reference to 33 points would come from assigning the following "points" to the 11 questions that were not eliminated from the original set of 14.

0 -- "better than usual"
1 -- "no more than usual"
2 -- "worse than usual"
3 -- "much worse than usual"

Total possible points = 11*3 = 33.  This is just my best guess, though.
Yes, that's right.

Within the paper, however, they make reference to a cutoff value for the Fatigue Scale on the unit interval (i.e., a score between zero and one).  Perhaps they obtain the zero-to-one score (which could of course be scaled to a 0-100 score) by dividing total points by 33?  Again just a guess given the incomplete description of the methods.  They ultimately decide that 0.75 (i.e., more than 24 points?) provides the optimal balance between sensitivity and specificity in correctly predicting how respondent would be categorized (fatigued or not) by some other questionnaire ("Revised Clinical Interview Schedule", fatigue question(s)).
No, it's simpler than that.
There are two ways of scoring it, bimodal scoring and Likert scoring. Bimodal scoring is 0-0-1-1 and Likert scoring is 0-1-2-3. So the possible scores with the two scoring methods are 0-11 and 0-33.
The threshold refers to bimodal scoring. If one scores 3 or less, one is not a fatigue case; if one scores 4 or more, one is. This has been "validated" (by comparison to another scale).

Interestingly, in the PACE Trial, the published protocol used the bimodal scoring as one of the primary outcome measures. However, most likely because they got the impression the results were not going so weel, and that there would be few people who would score 3 or less, the switched to Likert scoring in the final paper.

Mithriel raises an excellent point in that the "usual" state of affairs is a moving target as one's fatigue duration extends.

Also, they conclude that there are two significant* dimensions to fatigue (two significant principal components to their 14-dimensional data; two significant eigenvalues in the response covariance matrix (where responses have been quantified as I guessed above?)), but they apparently proceed nonetheless to use the single-dimensional Fatigue Scale score for categorizing patients.
Yes. One could still do that. What the two factors have been called in the past are "physical fatigue" and "mental fatigue".

For other people who are not familiar with this sort of analysis: sometimes people score similarly on certain questions.  For example, if one had a questionnaire that had a mixture of fatigue questions and pain questions, the scores for the fatigue questions might be more similar to each other than the pain questions e.g. say the questions were scored 0-100, one random person (who doesn't have ME) might score lots of really high scores for the fatigue questions e.gs 70s, 80s, 90s and really low for the pain questions e.g. 10s, 20s, 30s while the scores could be reversed for other people. So one might add all the scores of the fatigue questions together to get a fatigue summary score and all the scores for the pain questions to get a pain summary score.  Sometimes it is not immediately obvious what the common groupings might be so one can use statistical techniques like PCA to see whether there are common groupings within a questionnaire.  So in this case, they found that the questionnaire could be divided into two groupings and when one looks at the questions, "physical fatigue" and "mental fatigue" might be good names for the two groups.
Bundle of 4 links for:
11 surveys which found high rates of adverse reactions with GET;
Petition against (& info on) CDC's "empiric" CFS criteria;
The CDC's Dr James Jones on CFS over the years;
Various critiques of CBT school's view of & psychologisation of ME/CFS

Gerwyn

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Re: ? Chalder Fatigue Scale ?
« Reply #12 on: September 03, 2011, 12:55:02 PM »
 
 Its worth  pointing out that the above scale is not a scientific instrument.It is entirely subjective and based on self reports.A number of these scales claim to be validated.This means they (unsurprisingly) produce the same values as other subjective scales. None have been validated using objective(scientific) measurements of any kind



Tango

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Re: ? Chalder Fatigue Scale ?
« Reply #13 on: September 03, 2011, 01:15:40 PM »
Which means we can create our own for the Wessely School.

This is perfectly reasonable and it looks like it only requires a degree.

V Wessely School Scale - contains 11 questions

• Do you have problems with not being a scientist?
• Do you feel the need to remove yourself from science?
• Do you get bored by the pesky scientific method?
• Do you lack a scientific brain?
• Do you have trouble starting a study with objective measures?
• Do your methods have less strength?
• Do you feel there is a weakness in your study design?
• Do you have difficulty concentrating when reading the published literature on ME?
• Do you find it more difficult to find the correct word and change what you mean a lot?
• Do you make slips of the tongue when speaking?  I left research, I have not left research. 
• How is your memory on the PACE trial?
"I suspect there have been a number of conspiracies that never were described or leaked out. But I suspect none of the magnitude and sweep of Watergate." Woodward

"I would favor any name that does not impose (or give the appearance of imposing) taxonomic preconceptions on the nomenclature." Coffin

slayadragon

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Re: ? Chalder Fatigue Scale ?
« Reply #14 on: September 03, 2011, 04:33:41 PM »
Excellent, V.    :D

Of course, this is not a scientific instrument, Ger.

Someone just referred me to the "Full" write-up of the PACE study, which I had never seen before.  Apparently they keep it well hidden.

http://www.meactionuk.org.uk/FULL-Protocol-SEARCHABLE-version.pdf

The version of the Chalder Fatigue Score that they use is in Appendix 6.8, page 162.

1. Do you have problems with tiredness?
2. Do you need to rest more?
3. Do you feel sleepy or drowsy?
4. Do you have problems starting things?
5. Do you lack energy?
6. Do you have less strength in your muscles?
7. Do you feel weak?
8. Do you have difficulty concentrating?
9. Do you make slips of the tongue when speaking?
10. Do you find it more difficult to find the correct word?
11. How is your memory?

Scale, Items 1-10
Less than usual, 0; No more than usual, 1; More than usual, 2; Much more than usual, 3.

Scale, Item 11
Better than usual, 1; No worse than usual, 1; Worse than usual, 2; Much worse than usual, 3.

Best, Lisa
« Last Edit: September 03, 2011, 04:40:09 PM by slayadragon »