Assessment of recovery status in chronic fatigue syndrome using normative data (incl. on PACE Trial)

Dolphin

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http://link.springer.com/article/10.1007/s11136-014-0819-0

Assessment of recovery status in chronic fatigue syndrome using normative data.

Qual Life Res. 2014 Oct 11.

Matthees A.

Author information

Abstract

INTRODUCTION:

Adamowicz et al. have reviewed criteria previously employed to define recovery in chronic fatigue syndrome (CFS).

They suggested such criteria have generally lacked stringency and consistency between studies and recommended future research should require "normalization of symptoms and functioning".

METHODS:

Options regarding how "normalization of symptoms and functioning" might be operationalized for CFS cohorts are explored.

RESULTS:

A diagnosis of CFS excludes many chronic disabling illnesses present in the general population, and CFS cohorts can almost exclusively consist of people of working age; therefore, it is suggested that thresholds for recovery should not be based on population samples which include a significant proportion of sick, disabled or elderly individuals.

It is highlighted how a widely used measure in CFS research, the SF-36 physical function subscale, is not normally distributed.

This is discussed in relation to how recovery was defined for a large intervention trial, the PACE trial, using a method that assumes a normal distribution.

Summary data on population samples are also given, and alternative methods to assess recovery are proposed.

CONCLUSIONS:

The "normalization of symptoms and function" holds promise as a means of defining recovery from CFS at the current time.

However, care is required regarding how such requirements are operationalized, otherwise recovery rates may be overstated, and perpetuate the confusion and controversy noted by Adamowicz et al.

PMID: 25304959 [PubMed - as supplied by publisher]
 
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cman89

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Some recovery rate claims such as in the PACE Trial may not be justified because they used thresholds for recovery that weren't strict enough.
I see. that makes sense now. And of course the term "recovery" is so loaded with subjectivity that it can be imossible to quantify
 

Valentijn

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what is the significance of this in your opinion? I'm not getting it
Basically it's a statistics issue. In PACE they declared that one standard deviation below the mean for SF-36 questionnaire Physical Function (PF) subscale is sufficient to show recovery from disability. But SF-36 PF doesn't have a normal distribution, which anyone would learn in Statistics 101 is required for a standard deviation to be determinable and/or meaningful.

The result is that in the PACE study they declared a score of 60 means a patient is "recovered", even though something like 95% of a healthy working-age population scores 100 (maximum score) on the SF-36 PF. Hence by badly mangling statistics, they made it look like a score of 60 is normal, even though people actually have to be pretty ill or very old to score that low.

To make things even more absurd, CF patients were required to have a score of 65 or lower on the SF-36 PF subscale to be eligible to participate in the trial. Hence someone could be disabled enough to join the trial with a score of 65, become MORE disabled during the trial and have their score drop to 60, yet still meet the criteria for recovery.

There are many other outrageous issues with PACE, but this particular one is 100% governed by the rules of statistics, and the PACE trial authors made a huge and clear-cut violation of those rules. Hence it's a very useful angle for pointing out how badly flawed the trial was.
 
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A.B.

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what is the significance of this in your opinion? I'm not getting it

The significance is that the claims of CBT and GET leading to recovery in CFS are bogus, and the researchers behind it have no credibility. Either they are intentionally trying to deceive the public, or they are shockingly incompetent. I think the first option is more likely as there are too many problems and odd things about the PACE trial for this to be simple mistakes (in my opinion at least).
 

Kati

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Basically it's a statistics issue. In PACE they declared that one standard deviation below the mean for SF-36 questionnaire Physical Function (PF) subscale is sufficient to show recovery from disability. But SF-36 PF doesn't have a normal distribution, which anyone would learn in Statistics 101 is required for a standard deviation to be determinable and/or meaningful.

The result is that in the PACE study they declared a score of 60 means a patient is "recovered", even though something like 95% of a healthy working-age population scores 100 (maximum score) on the SF-36 PF. Hence by badly mangling statistics, they made it look like a score of 60 is normal, even though people actually have to be pretty ill or very old to score that low.

To make things even more absurd, CF patients were required to have a score of 65 or lower on the SF-36 PF subscale to be eligible to participate in the trial. Hence someone could be disabled enough to join the trial with a score of 65, become MORE disabled during the trial and have their score drop to 60, yet still meet the criteria for recovery.

There are many other outrageous issues with PACE, but this particular one is 100% governed by the rules of statistics, and the PACE trial authors made a huge and clear-cut violation of those rules. Hence it's a very useful angle for pointing out how badly flawed the trial was.
Thanks for the clear explanations, @Valentijn , it really helps.
 

Esther12

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even though something like 95% of a healthy working-age population scores 100 (maximum score) on the SF-36 PF.

I don't think that can be right. I've seen it stated that over 50% of the working age population had a score of 100 in the data-set cited by PACE, but I wouldn't have thought it would be much over 60%? It was still ridiculous for them to claim that a score of 60 was an acceptable threshold for recovery and that appx half of the working age population scored under 85.
 

WillowJ

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I don't think that can be right. I've seen it stated that over 50% of the working age population had a score of 100 in the data-set cited by PACE, but I wouldn't have thought it would be much over 60%? It was still ridiculous for them to claim that a score of 60 was an acceptable threshold for recovery and that appx half of the working age population scored under 85.

might the difference be "healthy working age" versus "working age" or "healthy"? Pretty sure if you restrict it with both "healthy" and "working age", it's unusual to score under 95 and highly unusual to score under 90 (making a score even of 85 a definitely in the lowest quadrant and possibly an outlier), though I do not recall the exact figures.

This is the data set [edit: healthy working age] which makes sense to compare to an average outpatient trial for ME or CFS/ME patients in general and the PACE trial in particular (as trials typically don't recruit (edit:) older patients (/edit), unless they are specifically studying geriatric patients... and the mean age in PACE was 40).

Some of the data sets cited by PACE were not how they were described in the papers (not the same age range, and/or not the same health status), but I do not now recall the details.
 
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Esther12

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might the difference be "healthy working age" versus "working age" or "healthy"? Pretty sure if you restrict it with both "healthy" and "working age", it's unusual to score under 95 and highly unusual to score under 90 (making a score even of 85 a definitely in the lowest quadrant and possibly an outlier), though I do not recall the exact figures.

This is the data set which makes sense to compare to an average outpatient trial for ME or CFS/ME patients in general and the PACE trial in particular (as trials typically don't recruit patients over 60/similar, unless they are specifically studying geriatric patients... and the mean age in PACE was 40).

Some of the data sets cited by PACE were not how they were described in the papers (not the same age range, and/or not the same health status), but I do not now recall the details.

Sorry - you're right, I'd totally missed the 'healthy'! I don't know about that data, but those figures could well be right.
 

Sea

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Not related to CFS, but still on the topic of conclusions of papers being different when reassessed with different statistical analysis or outcomes:

http://www.rheumatologynetwork.com/...3F-ACC5-F644DF548DC7&rememberme=1&ts=16092014

Among the 37 reports in the literature of randomized, controlled trials (RCTs) reanalyzed to verify their conclusions, 13 came to a different conclusion the second time around, this review points out. Two of these involved rheumatic conditions.
See more at: http://www.rheumatologynetwork.com/...rememberme=1&ts=16092014#sthash.FQY0I4am.dpuf

By using different statistical or analytical approaches, and different definitions or measurements of outcomes, a third of these 37 reports reached interpretations and conclusions different from those of the original article. - See more at: http://www.rheumatologynetwork.com/...rememberme=1&ts=16092014#sthash.FQY0I4am.dpuf
 

barbc56

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Researchers who want to claim their treatment leads to lots of people recovering can use very low standards for what 'recovery' means, and this should not be seen as acceptable. Good to see PACE used as an example of this.

That's a good thing and certainly refreshing to see.

There's a related thread on PR discussing an article written by Ioannidis where he points out this same issue with statistics.

http://forums.phoenixrising.me/inde...published-research-true-john-ioannidis.33320/

Barb
 

barbc56

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The significance is that the claims of CBT and GET leading to recovery in CFS are bogus, and the researchers behind it have no credibility. Either they are intentionally trying to deceive the public, or they are shockingly incompetent. I think the first option is more likely as there are too many problems and odd things about the PACE trial for this to be simple mistakes (in my opinion at least).

I believe these researchers really believe what they are saying. In some ways, I find this more frightening than the first scenario.

Barb
 

Valentijn

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I believe these researchers really believe what they are saying. In some ways, I find this more frightening than the first scenario.
I think they believe what they're saying AND are aware that their data doesn't support it. Hence they believe the data is "wrong" and they find ways to present it to make it comply with with their warped perception of reality.
 

A.B.

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I think they believe what they're saying AND are aware that their data doesn't support it. Hence they believe the data is "wrong" and they find ways to present it to make it comply with with their warped perception of reality.

Fake it till you make it?
 

chipmunk1

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I think they believe what they're saying AND are aware that their data doesn't support it. Hence they believe the data is "wrong" and they find ways to present it to make it comply with with their warped perception of reality.

Then the data will be used by the B*haviourists as solid evidence that can be used to lock someone up and torture them for their own good.
 
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