Title: PACE Trial - 97% of the participants who didn't have a psychiatric
disorder satisfied the definition of M.E. used
[I and others have noted these percentages in discussions on the internet
before; however, I thought the latest quote brings clarity to the wording in
the Lancet paper. Tom]
In the Lancet paper on the PACE Trial (by White et al (2011)), it said:
----------
"Participants were also assessed by international criteria for chronic
fatigue syndrome,12 requiring four or more accompanying
symptoms, and the London criteria13 for myalgic
encephalomyelitis (version 2), requiring postexertional
fatigue, poor memory and concentration, symptoms that
fluctuate, and no primary depressive or anxiety disorder
(interpreted as an absence of any such disorder)."
-----------
I was not 100% sure what "no primary depressive or anxiety disorder
(interpreted as an absence of any such disorder)" meant in relation to the
percentage we were given for "any psychiatric disorder" i.e. could there be
an overlap.
The following is an extract of a letter that clarifies it (see asterisked
bit) - the letter was written by PD White, KA Goldsmith, AL Johnson, R
Walwyn, HL Baber, T Chalder, M Sharpe, on behalf of all the co-authors (of
the PACE Trial)
---------
The trial did not study ME/CFS (pages 12-18)
The selection of patients was for CFS operationalised using the broadest
criteria (the Oxford criteria). No sensible neurologist would apply the
diagnosis of CFS (or indeed ME) to patients who had "proven organic brain
disease", such as Parkinson's disease. For the purposes of this trial ME was
not regarded as a "proven organic brain disease". In order to ensure balance
between the trial arms in those participants who met alternative criteria
for CFS and ME, randomisation was stratified by the International (Centers
for Disease Control) criteria (which require additional symptoms) and by the
London ME criteria (based on Melvin Ramsay's original description, and which
excludes co-existing "primary" psychiatric disorders [****which we
interpreted as any psychiatric disorder****] and emphasises post-exertional
fatigue). We were provided with the second revised version of the London ME
criteria; we did not invent our own. We considered use of the Canadian
criteria for ME but we found it impossible to operationalise them adequately
for research purposes; to our knowledge they have not been used in a major
research trial. We studied the results for differently defined subgroups and
they were similar to those in the entire group.
(source: http://www.meactionuk.org.uk/whitereply.htm )
-------
The figures from the paper (Table 1) show that, of the 640 participants, 300
(46.9%) had "any psychiatric disorder" and 51.4% (329) satisfied the London
criteria*.
This means that of the 340 patients in the trial (i.e. who satisfied the
Oxford criteria**, with a principal symptom of fatigue, who did not have a
psychiatric disorder), 329 (96.8%) satisfied the London criteria for M.E.,
the definition of M.E. used in the trial!
This is an amazingly high figure for a definition of M.E. given the
"looseness" of the Oxford criteria e.g. unlike the Fukuda CFS criteria or
Carruthers ME/CFS criteria, it doesn't require other symptoms apart from
fatigue.
It seems to me the definition for M.E., at least as it was used in this
trial, is very suspect. And hence it is questionable what can read from
into how people with M.E. responded in the trial.
Tom
----------
*One can how the London Criteria were used at:
http://bit.ly/lyqddJ i.e.
http://s982.photobucket.com/albums/ae301/tkindlon/?action=view¤t=Londo
n_Criteria_in_PACE_Trial.jpg
**
One can how the Oxford Criteria were used at:
http://bit.ly/kAh1cg i.e.
http://s982.photobucket.com/albums/ae301/tkindlon/?action=view¤t=Oxfor
d_Criteria_in_PACE_Trial.jpg
Annex 1:
We already cannot be sure if the participants are representative of patients
in the community based on who refused to take part, were excluded, etc.
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