On 2014 Jan 09, Tom Kindlon commented:
Further comments on the outcome measures being used and suggestions for other outcome measures that could be useful in such trials
(This was originally posted here http://www.biomedcentral.com/1741-7015/4/9/comments in 2009)
In the protocol, the authors say the following: "A 2001 systematic review of all treatments for CFS/ME concluded that cognitive behaviour therapy (CBT) and graded exercise therapy (GET) were the most promising treatments for CFS/ME, but that owing to the small number of studies available for review, the generalisability of these results could not be assured [1]*. The authors recommended that further studies be carried out using standardised outcome measures."
They authors neglect to say that the authors of that review also recommended the use of more objective outcome measures: e.g. "Outcomes such as 'improvement,' in which participants were asked to rate themselves as better or worse than they were before the intervention began, were frequently reported. However, the person may feel better able to cope with daily activities because they have reduced their expectations of what they should achieve, rather than because they have made any recovery as a result of the intervention. A more objective measure of the effect of any intervention would be whether participants have increased their working hours, returned to work or school, or increased their physical activities."
It is very disappointing that the organisers of this trial have not taken this on board with this study. Given the cost of the trial (over £1m), the cost of some actometers (for example) would have virtually neglible.
Existing research has some interesting findings on the issue. For example, one study (on a single patient)[2] found "using a 26-session graded activity intervention involved gradual increases in physical activity" that "from baseline to treatment termination, the patient’s self-reported increase in walk time from 0 to 155 min a week contrasted with a surprising 10.6% decrease in mean weekly step counts."The authors of the current trial refer to the Prins (2001) study[3] as an example of a study which supposedly found that hospital-based hospital-based CBT was an "effective treatment" for CFS. Judging by some of the questionnaire data, it does look like CBT has had an effect. However the actometer data from this study subsequently became available[4) and the increases in activity were minimal. For instance, the baseline average for the group which received CBT was 67.9, which increased to 68.8 after treatment and to 72.2 at follow-up. About 4 points. Not unlike the medical care controls, who went from 64.9 to 68.7 in the same period.
One of the aims of CBT (for CFS) has been said to be "increased confidence in exercise and physical activity"[5]. Thus it may be the case that when asked questions about one's ability to do things, such as in the physical functioning subscale of SF-36 (one of the three primary outcome measures in the FINE Trial), the patients might say that they are "Limited A Little" or "Not Limited At All" but may be just as limited as patients in other arms of study who say "limited a lot".
The physical functioning subscale is the primary outcome measure that is also being used to measure "clinically significant improvement" ("An improvement of 50% or more on the SF-36 physical functioning scale, or a score of 75% or more on that scale, will be considered a clinically significant improvement"). It is not an objective instrument, particularly in a psychosocial trial.
In my two previous comments, I have criticised the use of the bimodal Chalder Fatigue Scale as an outcome measure in a trial of patients with "CFS/ME". Recently another trial[6] was published involving CFS patients in the UK. The mean score was not given but the median mark was 11. That is to say, at least 50% of the people scored the maximum mark before the intervention. These people can not "get worse" on the scale using the scale even if they feel worse.
The third and final primary outcome measure being used is a quality of life measure. Although it may be useful to measure the quality of life, the findings of a recent study[7] make for interesting reading. It used 73 patients, also with a diagnosis of CFS according to the Oxford criteria, from UK clinics. It involved using principal-component analysis to analyse various bits of questionnaire. The Principal-component analysis of all scale scores revealed 2 distinct components, explaining 53% of the total variance. The results are summarised in the following extract: "The perceived incapacity in fulfilling social and physical roles may be best captured by the subscales of the SF-36 on social and physical functioning. The scores on these subscales are associated with vitality and inversely with one of the defining symptoms of CFS, i.e. fatigue (Chalder Fatigue Scale, Fatigue Visual Analogue Scale). They are also associated with other physical symptoms (SDQ, SCL-90-R subscale ‘somatization’), but not with psychological symptoms such as depression (Beck Hopelessness Scale, SCL-90-R subscale ‘depression’) and anxiety (Spielberger Trait Anxiety Questionnaire, SCL-90-R subscale ‘anxiety’). These psychological symptoms are linked to a generic measure of quality of life (MANSA), reflecting satisfaction with life in general and life domains, and to emotional role functioning and mental health (SF-36, subscale)."
Of course, the instrument to measure quality of life is different in this study so the relevance of this study is unclear at this time. But like the other two outcome measures (Chalder Fatigue Scale and SF-36 PF), the Euroqol is subjective.
It is disappointing that there apart from checking for the presence or absence of the CDC criteria, there appears to be no measurement of other symptoms apart from fatigue. (And of course I've already pointed out the problems with using the bimodal Chalder Fatigue Scale e.g. it's hard for some patients to score "worse" scores using the scale). But most researchers do not think CFS = fatigue. Even if some patients have few other symptoms because the Oxford criteria is being used, this should not have mattered.
(contd.)
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