Post-Exertional Malaise ... Related to Central Blood Pressure, Sympathetic Activity and Mental Fatigue in [CFS] Patients, 2021, Kujawski, Newton et al

Andy

Andy

Retired committee member
Abstract

Post-exertional malaise (PEM) is regarded as the hallmark symptom in chronic fatigue syndrome (CFS). The aim of the current study is to explore differences in CFS patients with and without PEM in indicators of aortic stiffness, autonomic nervous system function, and severity of fatigue. One-hundred and one patients met the Fukuda criteria. A Chronic Fatigue Questionnaire (CFQ) and Fatigue Impact Scale (FIS) were used to assess the level of mental and physical fatigue. Aortic systolic blood pressure (sBPaortic) and the autonomic nervous system were measured with the arteriograph and Task Force Monitor, respectively. Eighty-two patients suffered prolonged PEM according to the Fukuda criteria, while 19 did not. Patients with PEM had higher FIS scores (p = 0.02), lower central systolic blood pressure (p = 0.02) and higher mental fatigue (p = 0.03). For a one-point increase in the mental fatigue component of the CFQ scale, the risk of PEM increases by 34%. For an sBPaortic increase of 1 mmHg, the risk of PEM decreases by 5%. For a one unit increase in sympathovagal balance, the risk of PEM increases by 330%. Higher mental fatigue and sympathetic activity in rest are related to an increased risk of PEM, while higher central systolic blood pressure is related to a reduced risk of PEM. However, none of the between group differences were significant after FDR correction, and therefore conclusions should be treated with caution and replicated in further studies.

Open access, https://www.mdpi.com/2077-0383/10/11/2327/htm
 
This study is a little strange in that there was no standardised challenge that may induce PEM. So the PEM reported was due to naturalistic variation in the participants day to day lives. But PEM isn't merely a binary experience, greater exertion tends to lead to worse PEM...

For a one-point increase in the mental fatigue component of the CFQ scale, the risk of PEM increases by 34%.
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That seems like a backwards way of saying that patients who suffer from PEM report greater mental fatigue...

What is surprising is that the current results, corrected for multiple comparisons, showed no significant differences between the subgroup with PEM and that without PEM, in terms of fatigue as measured by scales.
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Which suggests the choice of scales are not relevant to capture PEM... I also would like to point out that ME/CFS patients have never been systematically asked as to whether these fatigue scales (CFQ, FSS, FIS) are relevant to their condition!
 
One-hundred and one patients met the Fukuda criteria. A Chronic Fatigue Questionnaire (CFQ) and Fatigue Impact Scale (FIS) were used to assess the level of mental and physical fatigue.
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1st. Fukuda - well okay, I understand they want to.compare patients who experience PEM with patients who don't but still....

2nd. CFQ - not suitable

3rd. FIS - not suitable as discussed in another thread recently.

4th. As @Snow Leopard has mentioned. PEM. What is it, is the researchers interpretation the same as the patients '? Do the patients' interpretation agree with each other?

Bit of a mess from the get go really.
 
Explicitly studying PEM and using Fukuda is indicative of a level of confusion that is certainly not compensated by the use of CFQ in terms of showing an understanding of the issues. It's basically uninterpretable because of this.

It's amazing how simple choices made early on can simply invalidate so much work before it even began. I'll never understand why researchers do these things, basically make their own work irrelevant by design choice. Oversight is so badly needed, the profession is adrift and unable to find its bearings.
 
I think the most significant result in this research is that of 101 patients diagnosed with CFS using Fukuda criteria, 19 did not report PEM.

If that is typical of patients diagnosed using Fukuda for research studies of ME/CFS, there may be significant problems with outcomes given the inclusion of about 20% of patients who do not have PEM.
 
to be clear how many people with m e had any knowledge of pem before 2010. in the first decade i was ill i had constant pem because i was always doing more than i should of thanks to non existent advice from my gp and of course the completely wrong advice from a cretin at Liverpool's school of tropical medicine since that was the only place of referral for a confirmation of my m e diagnosis.
 
Kitty said:
Indeed!

I also wouldn't be surprised if some of them don't realise they have PEM because no-one's explained the concept properly.
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Certainly doesn't help that most physicians seem to believe it means post-exercise fatigue and probably explain it in those terms with some added woo about mind-body blah di blah for why some people believe it's bad but it's nothing to worry about.

Literally the central concept and most of the "experts" completely misunderstand it. How anyone expects this to work out fine is a puzzle for the ages.
 
Trish said:
If that is typical of patients diagnosed using Fukuda for research studies of ME/CFS, there may be significant problems with outcomes given the inclusion of about 20% of patients who do not have PEM.
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Hey, maybe they're all curry-loving people that cumin works for as a PEM blocker. :)

As Invisible Woman says, it's a mess. It sounds like they did a poorly set up experiment and then tortured the results until it provided an interesting result.
 
Snow Leopard said:
What is surprising is that the current results, corrected for multiple comparisons, showed no significant differences between the subgroup with PEM and that without PEM, in terms of fatigue as measured by scales.
Click to expand...
Which suggests the choice of scales are not relevant to capture PEM... I also would like to point out that ME/CFS patients have never been systematically asked as to whether these fatigue scales (CFQ, FSS, FIS) are relevant to their condition!
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What is really surprising is that, 10 years ago, Newton and her team were being surprised that fatigue wasn't correlated with physical activity. And commented that probably the FIS fatigue measurement tool wasn't up to the job.
Hutan in the thread on the 2011 paper said:
It is good to see that the authors also realised that the FIS was not a good measure of fatigue
2011 Newton paper said:
We were surprised to find that there was no relationship between increased fatigue and reduced habitual physical activity, which is in contrast to other studies.20 We would suggest that this is explained by a ceiling affect in the symptom assessment tools i.e. a relatively low symptom burden leads to significant impact upon physical activity levels.
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10 years later, a team with Newton in it is surprised that FIS isn't up to the job.
 
In principle I think it's a good use of a Fukuda cohort to split it into with and without PEM and see what differences there may be between the groups. Any results of such a fishing expedition can then be used to generate hypotheses about the mechanisms of PEM.

For that to work you need a good way of separating the two groups and I'm not convinced that has happened here. Using fatigue levels as a proxy for PEM - even if the fatigue assessment tools had been better - increases the already high risk of confusion between PEM and post-exertional fatigue.

They seem to have performed the measurements without establishing whether a participant had PEM at the time? Or have I missed something (have been skimming)?

I wonder if a stricter PEM definition and testing before a CPET and again the day after would have given more conclusive results than what they got here?
 
Since JN does ME research and is an advisor to AfME perhaps we should invite her here to discuss her research to get some clarity on issues.

It's not like this would be a new thing since we have had several researchers here comment on their research. One would think that she would be willing and able to do this for the community that is the focus of some of her work.
 
Mij said:
I thought I was the only person who experienced this until around 2003 when I started reading about other ppl's experiences online, but it wasn't referred to as PEM back then, it was referred to as "wtf?".
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Does anyone know the origin of the term? When it actually began and out of what process? I only came aware of all this around 2016 so it was already there, though of course only spoken of by pwME.

So weird how it's a common term for long haulers, they understand it pretty well despite the natural confusion, and yet until last year not a damn person outside of the close circle of people interested in ME ever used those words or the meaning behind it.
 
rvallee said:
Does anyone know the origin of the term? When it actually began and out of what process? I only came aware of all this around 2016 so it was already there, though of course only spoken of by pwME.

So weird how it's a common term for long haulers, they understand it pretty well despite the natural confusion, and yet until last year not a damn person outside of the close circle of people interested in ME ever used those words or the meaning behind it.
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It is an interesting point. A friend’s daughter has Long Covid with very ME like symptoms and is pressing to move onto an ME diagnosis. She is using the term PEM, and has insights on pacing, cognitive issues, orthostatic intolerance and hypersensitivities that took me well over a decade to achieve. I think this is in part because we as people with ME in general and our charities/voluntary groups have been getting good information out there and that it strikes a chord with Long Covid sufferers.

It really illustrates how people with ME have been let down by our specialist services, that so many newly diagnosed are still not being provided with the basic tools to understand and manage their symptoms.
 
In the days before CFS, ME was considered a disease where there was an abnormal reaction to exercise which is close to the Workwell findings of damaged cellular respiration. Fatigue took a backseat.

Malaise was also considered a symptom. I was doing a university microbiology degree in the 70s and the word malaise was used to mean a flu like feeling so that may be how it was used in Fukuda.

The connection with exercise was almost lost when CFS was invented with it rarely being mentioned (if at all) by US researchers, it was all about fatigue. I wondered at the time if PEM referred to the flulike feeling that happened in ME.

Basically, we were stuck with the fukuda definition even though it did not match our symptoms and the problems in ME were shoehorned into a different language to talk about them.

When exercise problems were rediscovered all we had to call it was PEM which was fine amongst ourselves as we knew what it meant, the delay in it happening the lengthy recovery, but it was never a very good name or description.
 
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