Post-Exertional Malaise - a discussion including defining and measuring PEM

Moderator note: This post has been copied and following posts moved from this thread:
Epidemiological and clinical factors associated with post-exertional malaise severity in patients with ME/CFS. Ghali et al. 2020
____________________

PEM studies always catch my attention, especially ones that give a very good description of PEM in the introduction like this one does (it also uses an ICC cohort so all patients should by definition experience PEM).We sure need to know much, much more about PEM, how to identify and measure it, and what its relevance and implications really are.

Yet reading through this study the main take-away is that we also need much, much better instruments to study PEM.

1) So they used the "PEM item from the standardized self-reported questionnaire of Center for Disease Control and Prevention Symptom Inventory (CDC SI) [20]." The reference [20] is this paper: https://pophealthmetrics.biomedcentral.com/articles/10.1186/1478-7954-3-8 which discusses the "CDC CFS Symptom Inventory" which mentions "unusual fatigue after exertion" (table 2) amongst a whole raft of other symptoms like sore throat and unrefreshing sleep. It seems to be primarily designed to ascertain whether you have CFS, not whether you have PEM. In fact, there's no actual mention of PEM in this referenced study so I don't understand what the "PEM item" in the present study is supposed to be, the whole questionnaire or just the item "unusual fatigue after exertion"? Looking at the scoring section, the latter - "unusual fatigue after exertion" - appears to be the most likely. If so, I'm sorry but "unusual fatigue after exertion" ain't no measure of PEM, not by itself anyway. Which the authors know very well going by how they describe PEM in the intro - so why use "unusual fatigue after exertion" as a measure of PEM (if I haven't misunderstood something)?

2) They only asked about the last month, and they only asked about frequency and severity of PEM. One month is surely too short a period to assess frequency - or anything much, really - and they completely fail to take into account the impact of pacing on frequency and severity of PEM despite the fact that they discuss patients using pacing to reduce PEM.

3) Importantly they fail to investigate how much/little exertion is needed to set off PEM. Or if there's a link between the level of overexertion and the severity of PEM.

Not sure about this one. How do you decide whether your symptoms are those of an infection or of PEM? Do you simply have an infection or do you first have an infection which then sets off PEM? My personal sense is that infection and PEM are separate phenomena but that having an infection lowers PEM threshold, i.e. it takes less exertion to set off PEM when also having an infection. But it's hard to disentangle given that both infections and PEM present with flu-like malaise.

The second of the two tools proposed by the IOM for PEM assessment is the De Paul symptom questionnaire*. I wonder why they didn't use that? Unlike the CDC SI self-reported questionnaire it was specifically designed for PEM though it still doesn't account for the impact of pacing, nor assesses the amount of exertion that leads to PEM.

*https://www.leonardjason.com/wp-con...st-Exertional-Malaise-Questionnaire-DPEMQ.pdf

And the CDC SI self-reported questionnaire can be downloaded here: https://www.cdc.gov/me-cfs/pdfs/symptom-inventory-questionnaire-508.pdf

Is this something we could do better as a patient group? Many of the patient associations have good descriptive information on PEM but there don't seem to be any better scales than the two above to use in research.

ETA: Fixed plural of phenomenon (= phenomena). I do hope that once we find a cure for ME that the brain fog at least is reversible. I would really like to have my former command of language back!

 

I agree with you @Ravn, and i would like to add that many patients go through long periods of time without any infection (such as getting a cold), but PEM is often manifested by tender or swollen lymph node, sore throat and the feeling that an infection is coming.

 

The most important question for me is still 'What is PEM?'

Until we understand that, trying to measure it or predict who's most prone to it is really problematic. It can be hard even for patients who've been ill for decades to be sure until after the event whether they've had PEM, an ME flare, or a virus. If they have other chronic conditions as well, such as an autoimmune disease, it can be all-nigh impossible.

 

Investigating PEM is like trying to investigate insulin dependent diabetes by asking people about symptoms - do you get a headache after eating chocolate? Then you will get it confused with migraines.

The individual symptoms and how it manifests is, in some ways, not as useful as the simple question of what is the thing that makes your illness worse. For me it is always about what I do. While other things can have small effects it is the level of exertion that I need to be careful about.

One way of looking at diseases that no one ever mentions is asking patients what helps them. Years ago before I was diagnosed I struggled to find answers. I would check the index of books in the library (and flip through medical books in Waterstones!) for anything useful and one day there was "I have trouble going round supermarkets"

Eagerly looking in the chapter I was disappointed that she was better if someone was with her. I felt better if I took a trolley instead of a basket. That said something profound about what was wrong with me. Looking at things I did unconsciously, I always rested my arms on cushions and rested my forehead on the kitchen cupboard when I was peeling vegetables.

Over the years so many researchers have tried to define what we have but it all comes down to the fact that exertion is to ME what damaged lungs is to COPD, it is the system of the body that doesn't work.

If we did not have to prove we were ill and that was just accepted it would be much easier to try to help PEM.

 

Until we get some sort of biomarker for PEM I guess we're stuck with our current best-guess descriptions. Not ideal but still useful, especially the contrasting of PEM against other types of exertion intolerance, e.g. PEM is more than post-exertional fatigue.

Exactly!
Unfortunately that's pretty much all the existing PEM instruments do, list symptoms and ask about their frequency and severity.
Given how important PEM is to us we need researchers to have easy access to better instruments. We want them to study PEM and we want them to do it properly but until there is a better instrument they'll simply keep using the two existing ones just because they're there and accessible.
So how can we find a researcher keen to develop a better instrument together with us (major patient input is essential here I think)?

 

Maybe if we knock some ideas around ourselves & see if someone like Lenny Jason might take it further - his team have done the best work so far.

I wonder if it would be worth listing -

1 what specifically helps reduce the risk or severity of PEM - beyond general pacing

2 what, if anything, helps when we are in PEM?

 

Good questions, but frustrating that the answers have been known for over 60 years.

The risk of PEM is lessened if you follow what your body tells you. Stop when you have to. Not easy in real life but help for new patients sort out priorities, benefits so no one needs to struggle to work and make themselves sicker so they can eat and lots of aids to make life less energy intensive.

Then when you are in PEM, lots of rest. Proper research into whether you need to be lying down or sitting playing a computer game would help people a lot and would give parents tools to use with their children.

It is frustrating that answers would be more straightforward if they only believed us when we talk about our lives.

Teach us how to listen to our bodies and then scientists could add drugs, exercises and treatments on top that could help speed things up.

 

Sure, we know the answers in general terms. They've been known, and sadly ignored, for decades.

What I'm getting at is if we could somehow develop a template of PEM, its symptoms, it's triggers etc. ,- the negatives if you like and overlay that with the mitigating factors - as the questions above, could we come up with something that allows things like pacing on the effects of PEM to be factored in when attempting to measure or compare?

We all know in general terms what helps and what hurts but what would come out of a survey of the specifics for lots of individuals and would that get us any further forward?

 

For me, nothing (and believe me, I've tried!). I'm relatively mild, but I still have to space out things like a trip to the pool, meeting up with a friend, cleaning the house, or batch cooking. They always have to be followed by days where nothing is planned at all.

Just sitting it out, and avoiding self-criticism for flopping on the sofa all day when the house looks like a tip. Sometimes taking branched-chain amino acids seems to help, but it's too subjective to be a recommendation.

I do know when it's passed, I can clearly feel my body beginning to boot up again. This happened yesterday afternoon, after about five days of PEM due to hot weather and insufficient pacing the previous week.

 

Yep I understand what you mean @Kitty, but if we compared hundreds of answers of mild, moderate, severe, newly ill, 5 years in, 25 years in and diced and sliced the data with say the results of Lenny Jason's previous work on PEM would it further our overall understanding.

Is it something that could be fed into machine learning to pick out patterns?

 

Sorry, my reply came out much more negatively than I intended. I was hoping to learn more from others' responses, whilst acknowledging that I've made exactly zero progress in fathoming it out over the past four decades!

 

I didn't read it that way at all! I probably could have been much clearer in what I was trying to get at.

 

I agree that this is a vital question, and I have no doubt it will help if patients give a lot of input/a lead to researchers.

There are so many fundamental questions about PEM, not only what triggers/exacerbates it, but what it is. Jason's previous work on PEM came up with key features which don't reflect my PEM, and I get the impression that a lot of people here felt the same. Thankyou for discussing this important and slippery topic.

Edited to say: Rereading this post, it's a load of irrelevant dribble, excuse me. Sometimes writing it down and reading it back is the only way I can tell. I've deleted the rest now

 

Does anyone know if heart rate variability could be used to track PEM? @mariovitali reported that symptom severity tracked with HRV in his case if I remember right?

 

Should we have a new thread? We don't seem to be discussing the original study anymore but more generally how PEM could or should be studied.

Jason's PEM instrument is better than the CDC one (which isn't really specifically for PEM).

But I'm annoyed with him for ignoring me . When his team did their patient consultation process, I gave feedback, at least twice, outlining in detail the issues discussed here, i.e. the confounding effect of pacing on frequency and severity scores, and the need to include some questions about what level of exertion leads to PEM. Alas, my points were ignored .

I think they sought wider patient input too late in the piece, they'd basically already decided the overall design and were only able to make a few cosmetic changes in response to feedback at that point. In fairness I suspect most feedback they got was probably uncritical and along the lines of thank you so much for your work - we can be pathetically grateful for any sort of attention that isn't coming straight out of a certain BPS school. Note to researchers: often the best feedback comes from critical grumps !

 

Do we know where the ME/CFS Common Data Elements Project is at?

Bolding mine to highlight issues discussed in this thread. Good to see someone is thinking about them.

I haven't read the full document yet but so far have not seen mention of using the amount of exertion that triggers PEM as a measure of illness severity.

United States National Institutes of Health National Institute of Neurologic Disorders and Stroke Myalgic Encephalomyelitis/ Chronic Fatigue Syndrome Common Data Elements Project. Public comments, p. 87-89 and p.128-142. US National Institutes of Health. https://www.nih.gov/sites/default/files/research-training/initiatives/me.... Published March 2018.

ETA:
Have read some more and see that S4ME made an excellent and very long submission - which I'd forgotten all about - which also covered the point I was still missing above:

 

I believe I wrote a post in a previous thread a few months ago explaining what I believe is the difference between PEM and post exertional fatigue. Too tired to go looking for it now though but maybe somebody can find it.

 

Discussion split from
DecodeME - UK ME/CFS DNA study underway
Copied post

This confirms that my daughter will likely not be eligible for the study then, as her CPET results in October showed that she now doesn’t deteriorate after exertion, thus no longer has PEM. Technically, she no longer has ME and is in remission. Had she not taken the exercise test though, we’d be none the wiser and would still believe she met the criteria for having ME. Particularly as the reality of day to day life hasn’t changed at all since then and it’s still going to take her a period of years to fully recover her functioning capacity.

Such a knotty issue!

 

I don't think the CPET is a valid test of PEM. PEM is an unexplained symptom that may have nothing at all to do with what CPET measures. CPET was never validated as a measure for clinical use in individuals anyway. It was simply claimed to show a statistical difference between patients and controls. In the studies not all patients with ME showed 'abnormalities' and in fact showed different patterns. I don't think it should ever be used to make clinical decisions.