What is "Chronic Fatigue" in the Wessely School (CFS vs CF Wessely 1997, Prins 2006, White 2011)

Hello all,

I am very familiar with the ICC, CC, CDC vs Oxford criteria discussion, prevalence differences, Oxford obfuscation, etc. but I have a very specific question about what the Wessely crew mean by "CF" vs "CFS". This is not merely academic and is of consequence for important ongoing work.

More specifically

• White 2011 (PACE) cites Prins 2006 for the CFS prevalence ranges that PACE draws on, which in turn gets them from White 1997.
  
• Wessely 1997 table 2 (below) specifically breaks out a cohort without comorbid psych dxs, with the second column CFS numbers thus looking less potty than the first column.
  • But Wessley 1997 also bundles and breaks down CF into:
    • Idiopathic CF (i.e. CF that is not CFS by even Oxford criteria....)
      
    • and CFS.

I might be being a berk, but I can't see a proper clinical definition for CF itself by Wessley himself or gang anywhere (and I do mean by 'them' specifically, NOT by people being more rigorous through use of more relevant paradigms).


(from Wessely, 1997)

I even wandered into the Wessley 1995 'companion' cohort study and it didn't help (couldn't get more than the summary).

If you need the links:
Wessely 1995: https://www.sciencedirect.com/science/article/pii/S0140673695925376
Wessely 1997: https://www.ncbi.nlm.nih.gov/pubmed/9314795
Prins 2006 https://www.ncbi.nlm.nih.gov/pubmed/16443043
White 2011 (PACE) https://www.ncbi.nlm.nih.gov/pubmed/21334061

Many thanks indeed

 

Grateful if anyone can tag users who are major diagnostic-guideline / Wessely-school historians!

 

Idiopathic chronic fatigue was defined by the Fukuda criteria, namely:

I assume you mean the Wessely et al. 1997 study, not White 1997? I think they used the same definition as they refer to the Fukuda criteria (reference 20): "Idiopathic chronic fatigue (ICF) was defined as chronic fatigue failing to meet the criteria for CFS20." They don't mention that it should be unexplained fatigue though.

I don't think Wessely's prevalence study is reliable. It was originally intended to test whether there was an increased prevalence of CFS after an ordinary infection compared to patients who went to see their GP for other reasons. The prevalence rate Wessely reported in that famous 1997 study is based on the cohort that they used for the infection study. So their study design isn't quite right and their estimate is based on a very small number of patients.

The reported prevalence of 2,6% for Fukuda CFS seems way too high, given that Nacul et al. 2011 reported 0,2%. One reason for this might have been that fatigued patients didn't get a thorough investigation to exclude other causes. This isn't mentioned in the prevalence paper itself but in another study on the same patient cohort, Wessely and colleagues write:

The high 2,6% prevalence is usually rationalized by saying: "ow but if you exclude comorbid psychological disorder, you get a % that is similar to other estimates." But that doesn't make sense because those other estimates didn't exclude comorbid psychological disorders. Wessely and colleagues use the CFS patients that made up that high 2,6% estimate in many other studies, so I suspect these must be flawed as well.

Sorry, I digressed a little. Hope I've sort of answered your question.

 

Many thanks. Didn't realise they adopted some of Fakuda

Yup, indeed, thanks! Just fixed it to match my own article link. Two Ws and brain hiccup....

Totally agree and all your additionally shared context is additionally invaluable.

Totally agree also. Nucul's Fakuda based paper is extremely grounded and conservative. Other papers seem to assume 0.4%, if they have to assume something. From memory, it's because they assumed/accepted 100% underdx(?). Would need to relook at Nacul to how that dealt with or not, sample vs pop assumptions, etc. Johnson 2013 put down 0.76% for meta-analysis of clinical assessment on Fakuda criteria, but I've not examined how credible that paper is.

You helped alot and thanks for the invaluable digressions also

I am forensically considering the implications of specifically how Wessely et al dealt with this, rather than the right and wrongs of their approach. At least for this cut...

 

In my view the most reliable estimates of CFS prevalence were the studies by Jason et al. 1999 in Chicago and Reyes et al. 2003 (the CDC) in Wichita, Kansas. They found a CFS prevalence of 0,42% and 0,24% respectively.

These were community-based studies. They took a community that was representative of the US population and tried to contact all persons in that area (which is a lot, we're speaking of 20.00-40.000) to screen them for CFS. Of course, they could not all clinically examen these people, so they first used a questionnaire screening tool to select patients who indicate severe chronic fatigue. Then they took a sample of these persons and did a thorough clinical examination on them to see if they really had CFS (only a small percentage did). So that gave them an estimate of CFS prevalence.

There are a lot of problems with this approach: severe CFS patients might not respond to housecalls, they might not indicate they have severe fatigue ( because they are sick, not merely fatigued) etc. So this is a rough estimate. But it's the best one we have. In comparison: Wessely et al. looked at less than 2000 18-45 olds who went to see their GP and they only did some minimal bloodwork on them.

The Johnson et al. 2013 estimate of 0,76% is inflated in my view because it took an average of all studies and there are some bad ones that reported a much higher prevalence estimate. The most famous one is the second epidemiological study by the CDC, conducted in Georgia (Reeves et al. 2007). Here they adopted the Fukuda criteria, they used an empirical definition of the criteria which in practice came down to broadening the case definition. Others can probably explain this better than me.

I'm digressing again. In my view, the 0,2-0,4% prevalence estimate is the most accurate one at the moment and it's the one used by NICE. I think it's better to look at the few high-quality studies than to take an average of all of them, including the bad ones.

 

Thanks again. I'm a relative newbie compared to you guys who are in the bricks. My knowledge, wrt what I need to know, ranges from 99% to 20%. Where I am missing information is an unknown unknown. So thank you for digressing, it is useful contextualisation.

 

Apart from anything else, I also noticed for the first time that I have been using a wrong alternate spelling for Wessely....

 

I knew the other papers, but not Jason 1999. Usable CI ranges, which I needed. Thanks!

 

For some unknown reason I've always pronounced his name 'Weasel-ly'. I can't seem to change my internal voice's way of saying this when I read his name, even though I now know i've been spelling and reading it wrong.

It couldn't be because my brain keeps making this connection whenever I think or him: