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'Recovery' from chronic fatigue syndrome after treatments given in the PACE trial

alex3619

Senior Member
Messages
13,810
Location
Logan, Queensland, Australia
They are claiming 22% recovery after either CBT or GET. They are still using the SF-36 threshold for recovery at 60, which is of course classed as moderately disabled, which means their definition based on this is that recovery is moderately disabled or better though they never put it that way. Say what?
 

user9876

Senior Member
Messages
4,556
I wonder how this got throught peer review

We changed our original protocol’s threshold score for being within a normal range on this
measure from a score of o85 to a lower score as that threshold would mean that approximately half the
general working age population would fall outside the normal range. The mean (S.D.) scores for a demographically representative English adult population were 86.3 (22.5) for males and 81.8 (25.7) for females (Bowling et al. 1999). We derived a mean (S.D.) score of 84 (24) for the whole sample, giving a normal range of 60 or above for physical function.

They start by talking of the general working age population but then quote figures for a demographically representative english adult population. I think the first sentence is intended to mislead as they do no age matching.

Bowling paper available at
http://jpubhealth.oxfordjournals.org/content/21/3/255.full.pdf+html

The table on page 10 gives a breakdown of figures. The overall figures for the bowling survey seem to include 449 people with long term health problems (about 22%) and 319 people who had cut down their activity due to illness in the last 2 weeks (15%). So if you are measuring recovered to normal then these people should be removed thus boosting the figure. They scored 52 and 63 respectively in the sf-pf scale.
 
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We changed our original protocol’s threshold score for being within a normal range from a binary score of [less than or equal to] 3 out of 11 (White et al. 2007), which represented a screening threshold for abnormal fatigue from a small primary care study (Chalder et al. 1993), following the publication of a much larger study of fatigue in adults in a representative population sample of patients registered with a GP from South East England (Cella & Chalder, 2010). This showed a population mean (S.D.) Likert score of 14.2 (4.6) out of a maximum score of 33. We therefore considered a score of 18 (highest integral score below the mean plus 1 s.D.) or less as within the normal range for fatigue.
So they started with 3 out of 11 or lower as "normal", then shifted to 18 out of 33. If looking at the math (3/11 = 9/33), they effectively doubled the normal range.

And "normal" SF-36 went from 85+ to 60+, as mentioned above by user9876.

To satisfy the third criterion for severity of fatigue and disability, participants had to meet trial entry thresholds for fatigue (a binary score of [greater than or equal to] 6 out of 11 on the CFQ) and abnormal levels of physical function (a score of [less than or equal to] 65 out of 100 on the SF-36 physical function subscale) (White et al. 2007).
So on the Chalder Fatigue Scale someone could enter the study at 6/11 (18/33) and end it at 6/11 (18/33) with no change at all and be "recovered".

Talk about playing silly buggers with numbers.
 

alex3619

Senior Member
Messages
13,810
Location
Logan, Queensland, Australia
user9876, if you look at the population distribution in the Bowling paper, its highly skewed to the top end. Dropping the threshold to 60 means putting the recovery range as the sickest part of the population. By this I suspect most sick or disabled people would be classed as recovered. ATOS would love this.

Yet mostly mild patients were in this study in all probability.

Here is a question: what percentage of patients classed as recovered entering the study?

When are they planning a study in the severly ill, who cannot follow voice or written instructions?
 
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15,786
We considered scores of 1 (‘very much better ’) or 2 (‘much better ’) as evidence of the process of recovery, rather than our original protocol threshold of a score of 1 only, because we considered that participants rating their overall health as ‘much better ’ represented the process of recovery.
So basically "recovery" has been changed to mean "the presumed process of recovery".

To provide a definition of trial recovery, we calculated a hierarchical, cumulative definition that included the following domains mentioned earlier : normal range in fatigue, normal range in physical function, not meeting the Oxford case definition of CFS, and CGI scores of 1 or 2 (‘very much’ or ‘much’ better). To fulfil the criteria for clinical recovery from the illness, participants had to meet all the criteria for trial defined recovery (described earlier), in addition to not meeting either the International (CDC) criteria for CFS or the London criteria for ME.
And there are two sorts of recovery: "trial recovery" meaning no more chronic fatigue, and clinical recovery meaning no more CDC or modified London ME symptoms. So if the "fatigue" is not the primary symptom, but PEM, OI, etc are still in full force, they would meet the trial definition of recovered.

Cool, I'm already recovered and don't even need CBT or GET :p
 

user9876

Senior Member
Messages
4,556
user9876, if you look at the population distribution in the Bowling paper, its highly skewed to the top end. Dropping the threshold to 60 means putting the recovery range as the sickest part of the population. By this I suspect most sick or disabled people would be classed as recovered. ATOS would love this.

Yet mostly mild patients were in this study in all probability.

Here is a question: what percentage of patients classed as recovered entering the study?

When are they planning a study in the severly ill, who cannot follow voice or written instructions?

It you look at the distribution plots in Bowling they are not gaussian and hence sd is meaningless any way so shouldn't be allowed to use it to generate thresholds. How can a senior statistition from the MRC get things so very wrong.
 

Graham

Senior Moment
Messages
5,188
Location
Sussex, UK
Actually patients could enter with a score of 17/33 6/11 on the Chalder score (or technically even 12/33, although that would involve several answers of "better than usual" to questions on fatigue) and drop to 18/33 7/11 and be "recovered". You can even score 18/33 with a bimodal score of 9/11 although that would depend on a couple of answers being "better than usual".

There is an interesting quote in the report, "Alternative domains could have been used, such as return to work or objective measures of physical activity. Return to work is not, however, an appropriate measure of recovery if the participant was not working before their illness and is influenced by other factors such as the job market. Objective measures of physical activity have been found previously to correlate poorly with self-reported outcomes." In other words, our our assessments do not reflect reality.
 

alex3619

Senior Member
Messages
13,810
Location
Logan, Queensland, Australia
Hi Valentijn, I have little or no fatigue much of the time. There is always a sense that something is not right, but not fatigue, therefore my fatigue would class as close to zero. Yet when I do stuff I get into trouble fast: I have to slowly pace peeling vegetables for example. I also get severe brain fog, but thats not fatigue either. Nor is my syncope from NMH.

They dismiss using direct measurement of physical activity because it does not correlate with the questionnaire data. I would put it the other way around: throw out subjective measures and replace it all with physical measures. Functional capacity is objectively measurable, lets start with that.

Graham, our posts crossed.

user9876, ditto. I am aware of the issue with this not being a valid approach, but nothing shows it as well as a plotted curve and pointing out where the "recovery" threshold is. Its immediately visually obvious as bogus.
 
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15,786
The NNT [number needed to treat] for one extra participant to achieve trial recovery was 7 for both CBT and GET.

So ... if you treat 7 fatigue patients, only one of them will "recover" to the point that their fatigue score gets better OR stays the same (or gets worse as Graham pointed out), their SF-36 improves, stays the same, or drops by less than 5 points, "fatigue" is no longer the primary symptoms, possibly replaced by PEM/pain/etc, and they rate themselves as "much better".

By the way, the CGI (Clinical Global Impression) which uses the "much better" is designed for use by physicians in assessing improvement in patients. I have seen nothing showing it used by patients in self-rating in any other research, etc, and the assessment is supposed to be based on asking questions about the symptoms relevant to the condition being studied.
 

user9876

Senior Member
Messages
4,556
As I see it, trial recovery criteria
1) Chadler fatigue score below 18
and
2) SF-pf score above 60
and
not meets oxford criteria as judged by research assessor at 52 weeks. That is
not ( fatigue main symptom and
fatigue present > 50% of time and for more than 6 months and
SF-pf >= 65 and fatigue score>6 out of 11 (binary))
and a clinical global impression score of 1 or 2

The last bit of the oxford one in interesting. They basically say to meet the oxford criteria you need to meet the revised entry conditions + a couple of other things. That's an interesting one considering their other thresholds but the research assesor can just say that fatigue is not the main symptom.

I've not finished the paper but I haven't seen it say that the research assessors were blinded in their methods section. I would take the lack of any statement that they were to mean they weren't.
 
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15,786
Alternative domains could have been used, such as return to work or objective measures of physical activity. Return to work is not, however, an appropriate measure of recovery if the participant was not working before their illness and is influenced by other factors such as the job market. Objective measures of physical activity have been found previously to correlate poorly with self-reported outcomes (Wiborg et al. 2010), which may be related to the finding that activity patterns in CFS patients are heterogeneous, with only a minority being pervasively passive (van der Werf et al. 2001).
They must have been dropped on their heads when they were babies. A lot.

The prevalence of the case-level International (CDC) definition of CFS may have been inaccurate because we only examined for accompanying symptoms in the previous week, not the previous 6 months.
This could cause a varying level of CDC defined patients at various points in the trial, depending on how active they'd been in the past week.

The assessments of caseness (CDC, London and Oxford criteria) relied on a mixture of self-ratings and research assistant assessments, making some observer bias possible.
So it was pretty much up to the researchers to decide whose symptoms counted as fulfilling various criteria at various points.

Another interesting tidbit is that it's the Chalder Fatigue Scale which shows the biggest gap between CBT and SMC patients based on reaching "normal" scores, at 20% more CBT patients getting into the "normal" range compared to SMC patients. SF-36 only shows about half the difference, at 11%, which might illustrate that there was a much bigger improvement in "fatigue" related symptoms than in physical functioning. This might confirm that CBT tactics encouraging patients to deny feelings of fatigue is relatively effective (on questionnaires), but results in little difference in answering questions unrelated to fatigue.
 

Min

Guest
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Location
UK
http://www.meassociation.org.uk/?p=14331
A short debate on the controversial PACE Study has been tabled to take place in the House of Lords Grand Committee Room next Wednesday (6 February).
Put down by the Countess of Mar, the debate will consider The effects of the PACE trial on provision of health and social care and welfare benefits for people with chronic fatigue syndrome/myalgic encephalomyelitis.
The Countess is founder-chairman of the Forward ME Group of ME organisations that meets regularly at the Lords.
 
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15,786
Patients who have either CFS or ME characterized by a principal complaint of fatigue, and who are attending out-patient clinics, should therefore be offered either CBT or GET to provide the best chance of recovery with these treatments.
I think they're almost admitting that their trial (and therapy) is only applicable to chronic fatigue.

In addition to the usual "we need to try more/different/combined CBT/GET to see if it's more effective", they also add a rather rare disclaimer:
Finally, we also need to develop additional forms of treatment.
Granted, they only other forms of treatment they'd approve of would probably be psychological or psychiatric :p
 

Graham

Senior Moment
Messages
5,188
Location
Sussex, UK
In essence they still have not answered the question (surprise, surprise) of "I have classic ME but no psychological problems. Is there any evidence that CBT can help me?" With half of the patients suffering from psychological problems (33% depression), it is entirely reasonable to suggest that the CBT simply helped a small proportion of those who had such problems to improve, particularly if they were significant, and that there was no effect on the underlying ME.
 
Messages
15,786
In essence they still have not answered the question (surprise, surprise) of "I have classic ME but no psychological problems. Is there any evidence that CBT can help me?" With half of the patients suffering from psychological problems (33% depression), it is entirely reasonable to suggest that the CBT simply helped a small proportion of those who had such problems to improve, particularly if they were significant, and that there was no effect on the underlying ME.

Especially since the requirement of fatigue being the primary symptom would exclude many (most?) ME patients. It certainly isn't my primary symptom!
 

SOC

Senior Member
Messages
7,849
The degree of scientific and mathematical illiteracy among the BPS crew is appalling. The most basic stuff we teach in General Science to teenagers seems to be lacking -- correlation is not causation, design investigations to avoid unintentional (or intentional ;)) biases, carefully select your sample set so that it represents the group you are testing, don't draw conclusions beyond your data, and most basic of all, opinions are not fact.

I don't even want to go into their abuse, misuse and general ignorance about statistical analysis of data.