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Williams, White et al: PACE: Heterogeneity in CFS - empirically defined subgroups [...]

Hutan

Senior Member
Messages
1,099
Location
New Zealand
Very nice of them to finally provide an approximation of the percentage of trial participants who actually had ME
RESULTS:
The most statistically significant and clinically recognizable model comprised five subgroups. The largest, 'core' subgroup (33% of participants), had relatively low scores across all domains and good self-efficacy. A further three subgroups were defined by: the presence of mood disorders (21%); the presence of features of other functional somatic syndromes (such as fibromyalgia or irritable bowel syndrome) (21%); or by many symptoms - a group which combined features of both of the above (14%). The smallest 'avoidant-inactive' subgroup was characterized by physical inactivity, belief that symptoms were entirely physical in nature, and fear that they indicated harm (11%). Differences in the severity of fatigue and disability provided some discriminative validation of the subgroups.

I know your comment was slightly tongue in cheek Valentijn. But I don't think we can conclude anything about how many of the PACE participants had ME from this categorisation.

In my family sample of three (we all got ME at the same time), two years after onset, my daughter would fit in to the 'core' subgroup as she was only mildly affected and continuing with school and sport.

My son and I don't have mood disorders (although I don't know how the PACE people defined mood disorders) but it is quite possible to be diagnosed with a mood disorder and have ME. It has been (incorrectly) assumed at times that my son has anxiety about attending school.

We both have digestive system issues and joint and muscle pain - so we could fit in to the 'functional somatic syndrome' group.

We have many symptoms, so we could fit in to the 14% combined features group - again depending on how this was defined.

We aren't physically inactive but can't do what we did before. I strongly believe in a biomedical cause but my son periodically thinks that if only he could get fit he would be ok.

So, I actually have no idea how PACE would have categorised my son and I. But I suspect that all three of us would not have been categorised in that final 11% 'avoidant-inactive' subgroup. I think most people in that group would actually be better described as 'severely affected and knowledgeable'.

These PACE categories don't increase the understanding of ME. They also don't tell us how many PACE participants actually had ME.
 

Dolphin

Senior Member
Messages
17,567
The participants, who were still selected from secondary care facilities, had to be able to attend research and treatment sessions (and so were generally ambulant), and may be inherently more motivated to partake in treatment therapies than non-trial participants. The extent to which the results may be generalized to primary care patients, the severely disabled and patients with poor motivation to engage in therapies may therefore be limited.
Technically it is true that people who undertook the PACE Trial may be different from those who didn't take part. However it tested very specific therapies so I don't like the characterisation of people who didn't take part as having "poor motivation to engage in therapies". It does given insight into how the authors think about such patients and how they might describe them in other situations also.
 

Dolphin

Senior Member
Messages
17,567
Good that these points are specifically highlighted:
Limitations

[..]

Whilst we describe our subgroups as empirically derived, we acknowledge that the subgroups identified will be limited by the variables selected for inclusion, and that the majority of the decisions relating to variable reduction were undertaken post-hoc.

[..]

We did not include haematological or biochemical data and were unable to investigate the endocrine, metabolic and immunological abnormalities that have previously been reported. We may also have inadvertently excluded other measures that may have revealed different subgroups. Our assessments of sleep using actigraphy may also not be as detailed as the polysomnography that has been used in previous studies (Vollmer-Conna et al. 2006; Gotts et al. 2013).
 
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Tom Kindlon

Senior Member
Messages
1,734
CBRQ, Cognitive Behavioural Responses Questionnaire
Has anyone a copy of this? I don't think it has been published and it has been hard for me to find a copy (I have tried to look for it in the past).

Perhaps you could post it as an attachment, or alternatively send it to me in a Phoenix Rising message or by email tomkindlon at Gmail dot com. Thank you.
 

alex3619

Senior Member
Messages
13,810
Location
Logan, Queensland, Australia
Very nice of them to finally provide an approximation of the percentage of trial participants who actually had ME :p
Funny, but about a ten fold increase occurs when you move from ME to very weak definitions. That is why it goes from 0.2-0.4% of the population to over 2%, though the exact number varies by study. Whoda thunk it would happen here?
 

CFS_for_19_years

Hoarder of biscuits
Messages
2,396
Location
USA
Has anyone a copy of this? I don't think it has been published and it has been hard for me to find a copy (I have tried to look for it in the past).

Perhaps you could post it as an attachment, or alternatively send it to me in a Phoenix Rising message or by email tomkindlon at Gmail dot com. Thank you.

I did find a description of some of the scales and questions here on page 4:
http://dx.doi.org.sci-hub.cc/10.1016/j.jpsychores.2010.04.009
The Cognitive and Behavioural Responses to Symptoms
Questionnaire (CBRSQ [41])
is a newly devised scale that
assesses patients' cognitive and behavioural responses to the
experience of symptoms. This study used a 34-item version.
The five subscales dealing with cognitive responses are......(continue reading on Page 4)

Reference #41 leads to nowhere:
[41] Moss-Morris R, Chalder T, Skerrett T, Baldwin M. The Cognitive and
Behavioural Responses to Symptoms Questionnaire: measuring
cognitive and behavioural aspects of symptom interpretation.
In preparation 2009.
 
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Messages
13,774
I'd forgotten about this paper, but just saw that it's out in the June issue of Psychological Medicine (the same journal that published the PACE recovery paper).

The abstract makes it sound like the obvious thing to do would be to also look at differences in outcomes for their sub-groups and see if their were big differences.
 
Messages
2,125
Also published in July:
https://kclpure.kcl.ac.uk/portal/fi...OADES_Publishedonline9March2017_GREEN_AAM.pdf

Includes explanation of the form of CBT used for CFS/ME. And lest we forget who's theory it's all based on:

"Wessely’s model of CFS/ME postulates that a heightened focus on illness (and physiological symptoms perceived to be related to illness) reinforces an individual’s belief that they have an acute and potentially dangerous
disease, and as a result, they decrease their activity levels(Butler, Chalder, Ron, & Wessely, 1991)".

eta:
PACE.jpeg

.
 
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