I've noticed some disturbing trends in Long Covid ME/CFS research

These are mostly based on this paper by Haunhorst et al, which does have some good points, but which I found very frustrating to read. In no particular order, here they are:

Trend 1: Not recognising ME/CFS as ME/CFS. It’s strange. When a person with Long Covid meets the diagnostic criteria for ME/CFS, researchers behave as though that person doesn’t have ME/CFS. They’re just said to have Long Covid.

No other medical condition is treated this way. A person whose Long Covid includes anosmia (loss of sense of smell) has anosmia. A person whose Long Covid includes POTS (postural orthostatic tachycardia syndrome) has POTS. A person whose Long Covid includes tinnitus has tinnitus. So why is ME/CFS different?

Trend 2: Not recognising Long Covid as Long Covid. What is PCC? Oh, it’s post-Covid condition. I’m sure there must be some justification for using this unfamiliar and confusing term instead of the familiar patient-created one that everyone already knows. But I can’t help but think that researchers do this because they are so arrogantly hubristic, they can’t bring themselves to admit that patients named, recognised and accurately described Long Covid before doctors and researchers even realised it was a problem.

Trend 3: Changing the meaning of post-exertional malaise.

PEM has a distinct meaning. It is rigorously defined and measurable. There are a few different definitions and ways of measuring it, but all the modern and widely-accepted definitions make it clear that PEM is specific to ME/CFS, and is different from the symptoms of other chronic illnesses.

But the authors of the Haunhorst et al article, who, it’s pretty obvious, have only had a brief and shallow look into the ME/CFS research literature, confidently state that PEM can occur in other chronic diseases. They specifically mention fibromyalgia and multiple sclerosis. To quote the article:

Although PEM can occur in other chronic diseases, the severity and length of PEM allows to distinguish ME/CFS from other diseases with similar clinical spectrums such as fibromyalgia or multiple sclerosis.

This is a clear statement that PEM appears in fibromyalgia and multiple sclerosis. It’s untrue. It doesn’t matter that the authors qualify their untruth by saying that the PEM in ME/CFS is more severe and longer-lasting than the PEM that supposedly exists in other diseases. They are still re-writing the meaning of PEM, and enshrining this alteration in the research literature. A mistake like this is dangerous. It can muddy the scientific literature, bringing vagueness where there should be precision and clarity.

The article’s authors justify their bizarre re-definition of PEM to include fibromyalgia and multiple sclerosis by referring to a 2018 paper by Cotler et al, but this 2018 paper doesn’t actually mention fibromyalgia. It does mention multiple sclerosis, in the context that a questionnaire designed to detect PEM sometimes generates false positives from people with MS. The authors are clearly not saying that people with MS experience PEM. They are actually saying the opposite; that the symptoms of MS can sometimes unfortunately be mistaken for PEM although they are not in fact the same thing.

This is a bizarre mistake to make. It’s hard to understand what the motivation for it might be.

Trend 4: Lumping together all the Long Covid patients. Do they have ME/CFS? Maybe! No-one has bothered to check! Doing research with heterogenous patient groups is likely to give confusing results which muddy the research literature.

Trend 5: Matching people with ME/CFS to healthy controls who don’t have the same fitness level. Many years ago ME/CFS researchers doing cardiovascular studies learned to match their experimental participants to people with a similar level of cardiovascular fitness in order to control for deconditioning, which could otherwise be a confounding factor. The Long Covid researchers aren’t doing this, which makes their results harder to interpret.

Trend 6: The curse of the one-day CPET. Long Covid researchers are measuring cardiovascular parameters without bothering to check whether or not the patients are experiencing PEM. The results might be interesting, but PEM is the core feature of ME/CFS, and to gain greater insight into the processes that underlie it you need to compare a patient in their rested state to the same patient in a PEM state. This is another lesson ME/CFS researchers learned years ago, but many of the Long Covid researchers don’t seem to have caught on yet.

Conclusion: Are these innocent mistakes, or is it weaponised incompetence? Good science limits us to objective reality, but sloppy, poorly-thought-out science gives ambiguous results that can be used to justify anything at all, which may be far more convenient for some people!

I wrote this off the cuff and maybe I've missed something or been too harsh, feel free to let me know in the comments.

References

Haunhorst, S., Dudziak, D., Scheibenbogen, C. et al. Towards an understanding of physical activity-induced post-exertional malaise: Insights into microvascular alterations and immunometabolic interactions in post-COVID condition and myalgic encephalomyelitis/chronic fatigue syndrome. Infection (2024). https://doi.org/10.1007/s15010-024-02386-8. Available at https://link.springer.com/article/10.1007/s15010-024-02386-8

Cotler J, Holtzman C, Dudun C, Jason LA. A Brief Questionnaire to Assess Post-Exertional Malaise. Diagnostics. 2018; 8(3):66. https://doi.org/10.3390/diagnostics8030066. Available at https://www.mdpi.com/2075-4418/8/3/66