Rates of ME/CFS following Covid-19

Certainly Long Covid is a very broad thing but I had thought that it was well established that there's a subset who fit ME criteria. Is that not the case? I'm wondering if we're talking at cross-purposes.

 

I can see that, and maybe it’s what’s needed to get a result. But like you, I think it’s high risk, as well as not the right way to go.

The numbers are already pretty big, and I wonder if making them even bigger make the case that much stronger. Especially as a lot of politicians are even more dismissive of long Covid than they are of ME/CFS.

 

It’s only established more severe cases and those that found their way to specialist clinics or social media campaign groups. There’s no reason to assume they are typical of the whole, particularly when we know the whole are much milder and can qualify for long Covid with a huge range of symptoms.

nobody is suggesting that postviral fatigue should be merged with ME/CFS, in fact that’s one of the things people have tried to avoid, including Introducing severity threshold and making post exceptional malaise as the
cardinal symptom.

 

We seem to be epically at cross-purposes! I'm not suggesting that the ME/CFS subset of LC is typical of the whole - I don't think anyone is. I'm not suggesting either that PVF should be merged with ME/CFS, or that any of the criteria for ME/CFS should be removed to identify an ME/CFS subset of Long Covid.

To clarify, do you think that there is an ME/CFS subset of LC? Even if you think it's a much smaller one than the 50% touted?

 

I got ME/CFS from covid. I know many others that experienced the same. But I know far more patients that did not get ME/CFS.

So covid can cause ME/CFS. But that doesn’t mean that LC in general has anything to do with ME/CFS.

 

Yes, amongst those people who make it specialist clinics or are actively involved in social media groups who are not typical. I have no idea about the rest – the major majority. Some of them may have me/CFS, but I would like to see some evidence of this. I suspect most do not.

 

But there are PwME who never make it to the clinics or get involved in social media. The ME/CFS subset of LC is larger than the people in those places, surely? (I still have the impression that we are talking past each other a bit but that's the joy of the Internet.)

 

The absolute size of the subset doesn’t matter. It’s the ratio of the population that matter. And we know pretty much nothing about that.

 

It is not so much that the studies in the meta-analysis are duds but rather that a meta-analysis on this topic a priori is a dud (the meta-analysis we are talking about here is also a methodological dud with many errors but that doesn’t matter for the below discussion).

Long-Covid is very roughly defined as "anything new happening for at least 4 (sometimes 12) weeks in a 3 month timeframe following a likely Covid infection". ME/CFS is very roughly defined as "a disabling presence of certain symptoms for 6 months". So by definition there isn't really a canonical notion of ME/CFS prevalence in LC. Suppose you have one fixed cohort of LC patients that you're tracking. At 3 months everyone has LC, nobody has ME/CFS, at 6 months the amount of pwLC decreases but ME/CFS joins the picture, at much later time points the amount of pwLC decrease but the rate of ME/CFS amongst those that still have LC likely increases but that itself will depend on the cohort you’re looking at (it likely won’t increase if you’re only looking at hospitalised people who suffer from permanten damage or PICS). So in that sense there is no "fixed prevalence" and things depend on your study setup. Now this whole problem is complicated by your choice of cohort, are you looking at hospitalized people or different severities in the acute infection (then PICS and other things like a lower rate of onset of ME/CFS in elderly people joins the picture etc), how were they recruited, how does diagnoses look, how do you look at testing and asymptomatic infections, you will definitely need a control cohort, your cohort might consist of severe acute infections from the beginning of the pandemic but those have become rare now, how do you control for loss at follow-up (you'll likely loose people that recover but also some that become too severe) etc etc etc.

In short: If you look at everyone that has had LC (which includes people that are recovered after 6 weeks) at some point in time the number might be below 1% (just a rough guess), but if you look at young people with severe cases that actually influence quality of life and do a study with patients of longer symptom duration that number will likely start creeping up. With how bad LC research has been you’ll probably never get any of these questions answered well because the statistics are build on useless cohorts which people are now forced to work with.

So the question is more so: What would even be a meaningful question to ask?

To bring the discussion back on topic. It might not necessarily inspire confidence that this 50% was quoted in the letter, but people tend to write all sorts of nonsense in letters and proposals to make them more prominent, so I'm happy to ignore it. The question is much rather what does any of this mean in a slightly more concrete sense? Similar to @wigglethemouse I’d like to know what this means in terms of clinical services which seems like a thing that needs urgent addressing both from an ethical and humanitarian standpoint as well as for research.

 

Anecdotally I am in an international long covid support group because my ME got much worse from covid and I would say that a huge proportion, almost certainly a majority of the participants report PEM.

But of course these are the more severe and chronic illness aware people. People who have 6 months of fatigue and POTS generally won't join or leave quickly.

I think it would be a mistake to blindly include long covid but studying the subcategory of long covid with PEM alongside ME could be hugely valuble.

 

There clearly is and they meet many or all of the ME/CFS definitions and have many of the optionals as well but in a slightly different ratio when you sample on symptoms.

However there have been a number of papers, the first big 50% is ME/CFS is a classic, where they have shortcut the diagnostic process and used 1 or more symptoms of ME/CFS to mean they patient has ME/CFS or we have ME/CFS clinics choosing which patients have Long Covid based on what is effectively ME/CFS criteria. Given Fatigue is the most commonly found symptom of Long Covid meeting just 1 symptom can be an issue and it likely explains the recovery rates of Long Covid being all over the place depending on what they defined ME/CFS and Long Covid as. I have seen quite a few papers claiming to have applied WHO definition for Long Covid and CCC definition for ME/CFS and then you look into the method and they haven't, researchers aren't applying these definitions correctly so you have to check every paper in more detail.

Even when they ask Healthcare workers if they have Long Covid and if its ME/CFS we know most don't know the diagnostic criteria. I think its probably impossible to get a good answer without deeper analysis that is likely unviable currently. Due to a lack of government and healthcare interest in Long Covid and ME/CFS to find Long Covid patients you have to sample a large number of random people, find those with symptoms after Covid infections and then deeper assess every one on the clinical diagnostic criteria to ascertain if its ME/CFS. Since these population random studies looking at Long Covid prevalence are many thousands or 10s of thousands of patients or digital record assessment the deeper assessment becomes cost prohibitive.

I actually don't think we will get to a better answer to the percentage until healthcare is fairly reliable at applying the diagnosis of ME/CFS and Long Covid. Once that happens its possible to use digital records to correlate U09.9 and G93.3 and get a more accurate number with a cost effective study.

 

I think all we can say with certainty at this stage is that some people develop ME/CFS following Covid. As far as I understand, we don’t know if ME/CFS is caused by Covid-19 or any other virus. It could be that people who develop ME/CFS following infection would have developed ME/CFS anyway and the infection is just the trigger that tips them into the ME/CFS state, and/or it could be that people are particularly susceptible to infection prior to the onset of ME/CFS symptoms

As we know from reports of recovery following interventions, we cannot infer that A causes B just because B follows A, even if it happens very often.

I think this has been discussed before on another thread, which someone may be able to provide a link to.

 

Most of it is probably self-limiting in time but we shouldn't ignore the fact that this still represents a very high burden of short-term disability. It's still very expensive and disruptive to have so many people out of function for months in a context in which the cause is endemic, can happen to anyone at any time. In fact, the cause is multi-endemic, as it's basically any of a number of common pathogens.

It's possible that it wouldn't work like this, but I'd be shocked if treatments found for the chronic form of the illness don't apply to the self-limiting cases. Turning 6-12 months of prolonged illness into a few days is a major achievement with huge socioeconomic benefits. The stuff that pays for itself many times over in a few short years.

Performance is on a very steep curve at the top. Even a loss of 10-15% in normal performance amounts to a huge difference in abilities. It doesn't take much to knock people off the level of performance they need to be efficient at their job, even if those people are still able to struggle through shopping for necessities and a reduced workload of chores. In fact when brain fog comes in the picture, people can actually keep on working, but with a negative performance level, so they get paid to produce less value than their wage involves. This is a terrible lose-lose-lose scenario.

I would put it different, definitely ME/CFS isn't half of LC, but I would actually find ways to emphasize this problem. A higher number of shorter duration illness can still add up to a more significant burden than a lower number of indefinite illness. Actually, more resources are generally available to people who can barely maintain employment, as it's far easier than to bring people who haven't been able to work back to function, so the direct health care costs, which is always the main target of obsession, are far higher for short-term post-viral illness than for us remaining-of-life chronic sufferers.

 

I don't think any of this is really known, in part because we don't collect data during the acute phase from people with symptoms suggestive of these conditions. Doing this could turn out to be useful to delineate patients.

The 1 year cut off, where does that come from? I heard 2 and 3 years, too. The 6 months cut off for ME/CFS is also somewhat arbitrary and is very likely harming many people, that is apart from the shortcoming of not studying the condition in its acute phase.

Yes, we currently don't know who is who, but to conclude from that we should wait a year before investigateing is quite something. Collecting data from the get go and then follow up with patients periodically would be worthwile.