Preprint Development and psychometric evaluation of The Index of Myalgic Encephalomyelitis Symptoms TIMES Part I…, 2026, Horton, Tyson, Fleming, Gladwell

hotblack said:
Half of their limitations section is like asking someone what their weaknesses are and them replying ‘well I’m somewhat of a high achiever’.
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Yes, @bobbler mentioned it, but I was still very surprised when I got to the Limitations section and read this:

Limitations: The strengths of this study lie in the large, representative sample, the robust co-production with people with ME/CFS and clinicians working in NHS specialist ME/CFS services. The number of people with severe/very severe ME/CFS recruited is also a strength.
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After some elaboration about that, more praises are sung.
A further strength is the thoroughness with which the Rasch analysis was completed. It is unusual to see the complete cycle of scale development, analysis, empirical modification, and psychometric validation of the modified scale in a new cohort, and the conversion tables to
enable parametric analyses are rarely presented.
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Finally they get to some 'possible' limitations.
Possible limitations lie in the representativeness of the sample. The literature regarding the demographics of ME./CFS are sparse, so it is not possible to compare our sample with an authoritative source of epidemiological data. However, our demographics broadly reflect other large ME/CFS studies with convenience samples31-34: predominantly middle-aged women with moderately severe illness and extensive lived experience. Thus, we are confident data are reasonably representative of the ME/ CFS community.
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That seems to be saying 'we mostly talked to middle-aged women who are quite ill and have been ill for a long time, but that's okay, because that is what everyone else does too, and therefore we are confident that we have sampled a reasonable representation of the ME/CFS community'. Aside from that making no logical sense, it doesn't even seem to have occurred to them that the people who will be filling out the survey mostly won't be middle-aged women who have 'extensive lived experience' of ME/CFS. I would have thought that it was important to test the survey on people new to the illness and the language that is used to describe symptoms. For all their extensive and obscure validation, it doesn't seem that they did that.

The one limitation that they whole heartedly get behind is that it hasn't been validated in children. I guess that's because that is another nice bit of fundable work there.
 
Thanks @ME/CFS Science Blog for linking the questionnaire, it is handy.

On PEM, the one question in the Fatigue section is this:
Post exertional malaise (PEM). PEM describes a worsening of symptoms after seemingly trivial or undemanding activity of any description. It is often referred to as ‘a crash’. Onset may be delayed and it can be long lasting.
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Given it is a worsening of symptoms, a change from baseline, and given the measure is of frequency rather than impact on your life, it is pretty much impossible to score a '3' (all of the time) for this. It's an (almost) fundamental impossibility to have a symptom of periodic worsening and to be able to answer to the question
'Over the last month how often have you experienced this symptom' - 'All of the time'. If you had PEM all of the time, then you had no periodic worsening, so therefore you didn't have PEM....

Most people won't be able to say that they had PEM most of the time, most people are reducing activity so as to not be in PEM most of the time, if not consciously then because having PEM results in them staying in bed for a while and then recovering. Most people with ME/CFS will probably answer 'some of the time' and score a '1' for the symptom that is core to ME/CFS and undoubtedly is one of the most debilitating aspects of the illness. The way it is worded, it is very clear that you have to have experienced the symptom 'all the time', not just suffered from the knowledge that PEM could hit 'all the time'.

Because PEM is included in fatigue (because it is a consequence of exertion?), it means it is assessed by that frequency measure rather than the severity measure (i.e. how troublesome has this symptom been?). If it was assessed by a severity measure, then most people with ME/CFS would rate it a 3, because knowing you get clobbered most times you exert is very troublesome, as is having to spend days in bed feeling very ill.

There is no weighting of the fatigue scores in the total score. So that '1' from PEM contributes exactly as much to the total measure of ME/CFS symptoms as a mild problem with falling asleep when you want to, or a mild problem with excessive farting.

Contrast that with the sleep section: 6 questions about sleep - six opportunities to rate each symptom with a 3 (very severe). Even if you only rated each one a '2', that is 12 points. The survey seems set up to reward inputs from the clinic around sleep. If they manage to convince someone that they should not nap in the afternoon, that counts as an improvement, although it may mean the person is unable to prepare their evening meal.

This really is rubbish. All that fancy talk about validation, and they can't even properly recognise the symptoms that really count.
 
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Hutan said:
The survey seems set up to reward inputs from the clinic around sleep. If they manage to convince someone that they should not nap in the afternoon, that counts as an improvement, although it may mean the person is unable to prepare their evening meal.
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Yes, the BACME style clinics are obsessed with sleep management. Completely put of proportion or evidence. No amount of ‘sleep hygiene’ or ‘sleep management’ fixes the sleep problems caused by PEM or a crash (which they conflate but many of us distinguish).

The more I look at their way of trying to rate and score things the more it seems clear it sets up some very perverse incentives for both patient and clinic/clinician.
 
bobbler said:
BIt perturbed about this too



I'd be intrigued by the context and am not a fan of the wording of wired but tired. But these are some of the key features of PEM - wired but tired and bladder.

I'm not sure about the alcohol intolerance one - and can certainly see how in the hands of those who are going to use it relevantly (ie it being a clue for something scientific looking into mechanisms for biomedical cures) it is a bit of a strange one to fit in.


Ah... here we are:



So 58 items.

I somehow feel it will be a compromise of all types where it isn't specific enough to be useful whilst also being too long to be fair or doable.

I also worry that this is more about PPS 'persistent symptoms' and 'counting how many' and not 'studying the impact' or 'looking for patterns'.

Particularly due to what I have read above about melding mild and moderate so talk about not just having ceiling/floor effects but there not even being a possibility of differentiating in the middle categories either?
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I’m no scientist or researcher or statistician etc

Isn’t “it wasn’t giving a clear signal so we changed/ took out *symptoms* and *frequency* a bit “tail wagging the dog” aka you’re ditching measuring an illness symptom only because they way your measuring it isn’t saying what you want?

I still want someone to start a campaign about how the NHS is rolling out untested* treatments based on baseless ideas and symptoms.

*for the benefit of Sarah Tyson, I know she likes to obfusticate, I know she’s tested the validity of the questioning, I’m talking about tested regarding whether this helps or harms a patient with ME.
 
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