Can physical assessment techniques aid diagnosis in people with CFS/ME? A diagnostic accuracy study, 2017, Perrin et al

[Valentijn]

How did the first sentence of the conclusions get past peer review?

The same Puri who was a lead author from the older paper about just the single Perrin tender spot, and has had his fish oil promoted by Perrin, was Reviewer #1 of this new diagnostic paper It's possible that some of the other reviewers are dodgy too.

 

[Joel]

Leaving aside the issues around unproven claims being promoted about the treatment, this study created a hamstrung diagnostic method to compare against which had the effect of making the Perrin technique look better than it was.

If we compare against the actual standard NHS diagnostic practice which was presumably used to diagnose patients taking part in the study in the first place (albeit one performed outside of trial conditions and at an earlier point in time) the Perrin technique fails to achieve the same rate of diagnosis and also produces false positives. Where then is the value from a diagnostic point of view?

It seems they are highlighting that the examination only takes 20 minutes as a positive (probably about five minutes shorter than the consultation I had when I was diagnosed, not sure what the standard amount of time is for an NHS diagnosis consultation?). Not a huge saving, especially as it would be inappropriate in a clinical setting not to take a history and ask about symptoms anyway. And do we ignore the problem of false positives which the technique introduces? Also we don't know if the technique would perform the same, worse or better at an earlier point in time, at the point where patients receive their standard NHS diagnosis and that may be important.

And the biggest question of all, as mentioned before: can the Perrin technique tell ME/CFS patients apart from disease and sedentary controls as the current diagnostic method attempts to do. This is a vital test which they've made no attempt to prove yet. Till they do they really should not be claiming success like they are even as a diagnostic method.

 

[Joel]

First of all, sorry for going back to an earlier point in the thread. It's hard to keep up.

1) and 2) would be desirable but they are not necessary. I'd be satisfied with a variation of 3), i.e. that even in the absence of biomarkers, patients can be objectively shown to improve with therapy.

What do we do if the phase III rituximab trial shows a positive result but no one is yet able to demonstrate the pathophysiology? If, for example, 25% have a sustained recovery, 10% recover initially and then relapse and a further 35% show significant improvement, and you had a spare few thousand in your pocket, would you take the chance at those odds? Other than being able to identify whether you are likely to be a responder, does it matter if the agent is not yet discovered?

Agree that the pathophysiology isn't needed to make something useful either as a diagnostic or a treatment, but the issue here is that Perrin is making claims about pathophysiology without prior proof to back them up while selling the treatment privately. Not sure if anyone is selling Rituximab with such certain claims being made about the pathophysiology and even if they were at least we have two well conducted trials showing the treatment does appear to work in those trials (whatever the reason why).

 

[alex3619]

and

Perrin technique aside - we have no way of knowing what criteria were actually used to diagnose these patients. If the second quote literally means that a single physician was used to confirm the diagnosis it just means that they fit this individual's idea of what ME is.

Bolding is mine - Showing agreement with current diagnostic techniques doesn't inspire me with confidence. As far as I am aware the current diagnostic techniques aren't that great and this piece doesn't mention any tests to rule out other conditions. I don't have a whole lot of faith who don't understand that accurate diagnosis is a major issue with this disease.

Probably NICE guidelines for patients. If it was Oxford then we can totally discount the study. Does anyone know which diagnostic criteria for sure?

Current diagnostic techniques are fundamentally flawed, so I agree I cannot have confidence. Where was the validation using CCC or ICC?

The issue here is we cannot be sure they are wrong. We can, justifiably, have doubts.

Edit:

Potential participants who were aged between 18 and 60 were assessed using two forms: a recruitment screening form based on the NICE guidance5 and a form based on the International Consensus Criteria2 (reference standard).

(from the paper)

 

[alex3619]

Leaving aside the issues around unproven claims being promoted about the treatment, this study created a hamstrung diagnostic method to compare against which had the effect of making the Perrin technique look better than it was.

Big pharma does this frequently using comparison groups, not placebo. Give the wrong drug, in the wrong dose, or with the wrong protocol, and compare it to your drug.

 

[alex3619]

Let us suppose this test has a high sensitivity, though current ME testing has sensitivity to 95% which is clearly superior, though more expensive. It still suffers from specificity, which is the bane of a lot of testing. We cannot be sure the findings are not due to other issues.

Edit: The sensitivity and specificity results given are only as good as the methodological limits. If we did the same thing with other things, like the two day CPET protocol, we could claim 100% specificity, and 95% sensitivity at least. Yet its misleading to do that. We need to cast a wider net, with a large sample size, including many more diseases, to start talking about specificity aside from a technical figure.

 

[alex3619]

I have ME/CFS but don't have swollen lymph nodes for instance.

For perhaps a decade I did have swollen lymph nodes. Then they went away. Then about a decade ago I came down with a chronic sore throat. I am still waiting for that to go away.

 

[alex3619]

Let us be fair though, we should not be requiring this study meet the standards of mature research. Its early days. What we can do is say something like "OK, there is a possibility there is something to this, please do a follow-up study with better methodology. " Most possibilities that are raised in research turn out to fail on follow up.

 

[alex3619]

At that time, they weren't sure how you could design a trial when you cannot blind the treatment and you have to reply on subjective reports.

Yes, its the same flaw. However the sentence implies the solution. Do not rely on subjective outcomes, use objective outcomes, then base any claim of success or failure on the objective outcomes. This does not remove the need for sound methodology however.

 

[Sly Saint]

as per another thread on the Perrin technique,
Perrin is continuing with his courses based on this research.
Mar 13
Chronic Fatigue Syndrome/ME & Fibromyalgia-13-14 March 2021

About the course
Dr Perrin will detail the evidenced based diagnosis, treatment and management of Chronic Fatigue Syndrome (CFS)/ Myalgic Encephalomyelitis (ME) and fibromyalgia.

The evidence to support the physical diagnostic criteria

A summary of the findings of the clinical trials into the treatment at the Universities of Salford and Manchester together with results of an independent controlled clinical study in Hammersmith Hospital London plus a detailed review of the findings from the diagnostic study published recently in the BMJ Open (Hives L et al. Nov 2017)

given that this diagnostic criteria bears no relation to the new guidelines (or the old ones), it highlights the problem with 'evidence-based' diagnosis/treatment/training (issues that were raised in relation to new training courses to reflect the changes in the guidelines).

https://www.eventbrite.co.uk/e/chro...omyalgia-13-14-march-2021-tickets-73795890495