Ryan 2017 (PACE Trial data) Psychometric properties & factor structure of a shortened version of Cognitive Behavioural Responses Questionnaire (CBRQ)

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Psychosomatic Medicine. Publish Ahead of Print():, OCT 2017

Psychometric properties & factor structure of a shortened version of Cognitive Behavioural Responses Questionnaire (CBRQ)

DOI: 10.1097/PSY.0000000000000536

Ryan EG1, Vitoratou S, Goldsmith KA, Chalder T.

PMID: 29023262

Issn Print: 0033-3174

Publication Date: 2017/10/10

Abstract

OBJECTIVE:

Symptoms of chronic fatigue syndrome (CFS) can be perpetuated by cognitive and behavioural responses to the illness.

We aimed to determine the factor structure, reliability and validity of the 40-item Cognitive Behavioural Responses Questionnaire (CBRQ) using data gathered from CFS patients.

We also propose a short version CBRQ for greater clinical utility.

METHODS:

The psychometric analysis was performed on datasets drawn from two sources: a clinical service for CFS patients (N=576) and the PACE randomised controlled trial (RCT) of CFS treatments (N=640).

An exploratory factor analysis (EFA) was conducted on the clinical dataset and a confirmatory factor analysis (CFA) was performed on the RCT dataset.

Using these results, a short version of the CBRQ was proposed.

Reliability, metric invariance across age and sex, and construct validity were assessed.

RESULTS:

The EFA (relative Chi-square 2.52; RMSEA 0.051; CFI 0.964; TLI 0.942) and CFA (relative Chi-square 4.029; RMSEA 0.069; CFI 0.901; TLI 0.892) revealed that eight factor models fitted the data well.

Satisfactory Cronbach's alpha values were obtained for the final subscales (≥0.76).

The shortened CBRQ was obtained by removing items that cross-loaded onto other factors and/or were the lowest loading items in each factor.

The shortened CBRQ contained 18 items which had high factor loadings, good face-validity and reliability (Cronbach's alpha 0.67-0.88).

CONCLUSIONS:

The CBRQ, long and short versions, are reliable and valid scales for measuring cognitive and behavioural responses of patients with CFS.

Further research is needed to examine the utility of the CBRQ in other long-term conditions.
 
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I'm not sure I will read this but I thought this was interesting:
PACE patients were also required to have an SF36 score ≤60, which was later increased to ≤65; 348/576 (60.4%) patients had SF36 ≤60 in the clinical dataset and 377/576 (65.5%) patients had SF36 ≤65.
Click to expand...

People will recall a score of 60+ was a recovery criterion in the PACE Trial in which Trudie Chalder was a principal investigator.
 
This is now on sci hub, but for some reason it didn't give me a direct link to post (never done that before).

I gave up reading this half way through - it just looked like more pointless building on a foundation of sand. I did skim the rest and pull a couple of bits out in case they interest others.

A bit surprising that this point was supported by two papers from 1991 and 1993:

"Most studies have found that CFS patients do not have significant differences in
physiological test results compared to controls (e.g., 4, 5). Shortly after its recognition as
an illness (6, 7), clinical researchers postulated a cognitive behavioural model of CFS that
hypothesised that CFS symptoms are perpetuated by the patients‟ cognitive and
behavioural responses to the illness (8, 9). Some of the unhelpful cognitive responses in
patients with CFS include excessive focusing on fatigue symptoms (10), and catastrophic
interpretations of symptoms which involves worrying about worst-case potential
consequences (11). These cognitive responses are also associated with behavioural
responses in CFS patients, which include reducing or avoiding activities to alleviate
fatigue (12, 13), or alternating between high levels of activity when feeling well and
resting excessively in response to symptoms."​


4. Wessely S. Chronic fatigue syndrome. J Neurol Neurosurg Psychiatry 1991; 54(8):
669-671.
5. Gibson H, Carroll N, Clague JE, Edwards RHT. Exercise Performance and
Fatiguability in Patients with Chronic Fatigue Syndrome. Journal of Neurology
Neurosurgery and Psychiatry 1993; 56(9): 993-998.​

PACE is reference 14:

"The therapies that have been shown to be effective in CFS, such as cognitive behavioural
therapy (CBT) (14) are based on identifying and targeting unhelpful cognitive and
behavioural patterns in CFS patients (9). It follows that accurate measurement of these
factors is critical to the assessment of whether treatments are working as expected and to
the refinement of treatments, so that they have the maximum possible effect on changing
beliefs and behaviours that perpetuate CFS symptoms."
​
It seems a bit odd that their getting to work on this supposedly 'critical' measurement only after 30 years of promoting their 'treatments' to patients.

Here's some more from the bit where they compared their clinical sample to the PACE sample:

"The duration of illness was generally longer in the
clinical dataset compared to the RCT dataset (median 48 vs 31.5 months; P < 0.001). An
inclusion criteria for the PACE study was that patients had a CFQ score ≥ 6; 473/576
(82.1%) patients in the clinical dataset met this criteria. The mean CFQ score (bimodal)
was 9.3 (SD=2.8) in the clinical dataset, and the mean in the RCT dataset was 10.3
(SD=1.2) and a significant difference was found between these means (P < 0.001). PACE
patients were also required to have an SF36 score ≤60, which was later increased to ≤65;
348/576 (60.4%) patients had SF36 ≤60 in the clinical dataset and 377/576 (65.5%)
patients had SF36 ≤65. The mean SF36 value in the clinical dataset was 46.9 (SD=26.4);
the mean SF36 in the RCT dataset was 38 (SD=15.7) (P < 0.001). Due to trial entry
criteria, the RCT patients had worse fatigue and disability than the clinical CFS patients"​

Maybe this is of some interest, but I think that we'd already looked at those questions was just transaparently misguided as a way of assessing the 'catastrophising' cognitions of patients with a condition like CFS:

"Although the catastrophising items have been used in previous papers (16, 17) and
catastrophising was found to be one of the mediators of the effects of CBT and GET for
CFS, we found these items to be problematic, with low factor loadings and evidence that
they cross-loaded on to other factors. It may be that the items were not specific enough
and/or overlapped with other constructs. In the proposed short version of the questionnaire
we have removed these items since we wanted to obtain a questionnaire with as strong
indicators as possible. The six factor model (with 18 items) explained 67% of variance in
the data, whereas the eight factor model (with 40 items) explained 60% of the variance in
the data. By removing problematic items, the latent structure became clearer.

We also removed the avoidance items from the short version of the questionnaire as they
cross-loaded on the fear avoidance factor or the catastrophising factor. It is likely that these
items are not required in the presence of the fear avoidance items. The subscales/factors in
the short version had good reliability and the items had large factor loadings and no cross
loading."​
 
Esther12 said:
Most studies have found that CFS patients do not have significant differences in
physiological test results compared to controls (e.g., 4, 5). "
Click to expand...
This sort of cherry picking of the literature to fit a particular belief really makes me FURIOUS! I cannot believe this sort of thing is considered mainstream medicine. Imagine if you were trying to do a study of homeopathy, and you only cited the studies that supported your strong belief in its effectiveness? You'd never get past first base. Yet this stuff gets waved through without question!
:mad::mad::mad::mad::mad:!
 
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