Post-exertional malaise among people with long COVID compared to myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), 2023, Bateman et al

This may be due to the newness of Long COVID, not knowing what exertional intolerance is or how to manage it.

Almost certainly.

 

From the introduction:

[1] Pathak H, Mohan MC, Ravindran V. Chikungunya arthritis. Clin Med. 2019;19(5):381–5.

That's a surprising thing to lead with; that's in the first paragraph, and the first reference. I was intrigued, as we have looked at some of the reports of post-chikungunya arthralgia (click on the chikungunya tab above), and the numbers reported have been small, and the evidence of chronic rheumatic disease as a result of chikungunya a bit questionable. So, if 10 million people had been documented as suffering from this, it would be news.

That reference is interesting, but nowhere does it say that the Chikungunya virus epidemic has caused more than 10 million cases of chronic debilitating rheumatic disease. The only occurrence of the word 'million' in the arthritis paper is this, talking about the acute disease:

Numbers of acute infections don't appear to have ballooned since then. In 2022, the number of people infected with chikungunya was reported as 383,000 people. Those numbers make it more likely that there has been only around 10 million people affected by the acute disease, making the statement in the Long Covid paper very unlikely.

Why would the authors lead with this in a paper about PEM in Long covid?

 

This statement is not supported by the results. The results in what are fairly small samples are amazingly similar, considering the questions were not administered in exactly the same way:

and also considering the Long Covid people haven't been sick very long.


I'm not that impressed with these authors pushing the idea that depression and anxiety is an intrinsic feature of ME/CFS, Long covid and other post-infection conditions:

Ebola virus disease survivors typically live in countries with minimal social welfare safety nets. They have typically lost many of their relatives. Often their homes and their personal effects will have been burned. They face a lot of discrimination, which can make it hard to find employment even if they do have enough energy to work. In such a situation, answers to any questions along the lines of 'how do you feel?' probably aren't going to be super positive.

The people with Long covid are in the earlier stages of their illness, of course they are feeling worried and upset. The data table reports the percentage for "depressed and anxious" which is rather different to "having depression" and "having an anxiety disorder". I can imagine a lot of people saying yes, to a question 'do you feel depressed and anxious about things?" when they feel rubbish, don't feel able to do all the things they used to do and are worried about paying the bills.

At least some of the authors are very familiar with ME/CFS and post acute infection conditions generally. They really should know that the evidence for depression and anxiety disorder being a core part of these illnesses is pretty weak. Given the lack of evidence, it's unhelpful to be pushing that idea. It encourages many people to think that the person has a mood problem, with appropriate first-line responses being psychotherapy and anti-depressants rather than assistance to obtain practical support.

 

Bateman Horne Center.

 

A couple of things stand out for me as problematic with this research.

First, their description of PEM is all about increases of symptoms, but there is no mention, either in the description or the questionnaire the patients filled in, of the other main feature of PEM, namely a significant reduction in ability to function for at least 24 hours. The description would seem to include what I refer to as the effects of fatiguability that happen to me during and after all activity, with effects lasting for hours, but that's not PEM if I can function at the same level on following days.

Secondly the questionnaire has ambiguities. For example it offers as possible choices PEM happening after low, medium and high physical exertion, without making it clear that you can choose all 3. So from the results, it seems that pwME are less likely to get PEM after high exertion than medium exertion, which is clearly nonsense. Some may tick all 3, others may just tick the lowest level at which PEM occurs.

From the results table: Column 1 is LC, column 2 is ME/CFS and column 3 is the p value for between group differences.
Low physical exertion 14 (18%) 33 (22%) 0.49
  Medium physical exertion 67 (84%) 108 (72%) 0.31
  High physical exertion 58 (73%) 48 (32%) <.001
Similarly for the 3 levels of cognitive exertion.

And the what you do to prevent PEM has some ambiguities too, which seem to lead to different strategies, but may be more an artefact of how we describe what we are doing.
The options for prevention are:

So to me, for example, physical awareness is a key part of pacing, as is avoidance and lifestyle. So do I choose them all or just pacing?

Edit:
Another ambiguity:
In the section on what you do during recovery from PEM;
Light activity 21 (26%) 6 (4%) <.001
So it looks like far more pwLC use light activity than pwME.

But does light activity mean reducing from medium or high activity to light activity, ie cutting back activity, or does it mean actually trying to keep up light activity rather than resting? These are opposite strategies, not made clear. The difference may be simply a difference in interpretation of whether light activity refers to cutting back or pushing through.

 

You mean Table 2? PEM onset and recovery look very very similar to me. None of the differences are significant, according to the p values.