Issues to consider in dietary intervention studies in ME/CFS

R

RoseE

Senior Member (Voting Rights)
Posts moved from News from Aotearoa/New Zealand and the Pacific Islands

RoseE said:
I have been contacted by a gastroenterology dietitian at Christchurch Hospital, NZ, who is also a researcher at the University of Otago Christchurch. They are wanting to discuss their ideas for research into the role of nutrition in the management of ME/CFS - with someone /people living with ME/CFS. They are planning to apply for one of the ANZMES research grants.
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The dietician has asked "how feasible it is to measure people’s experience of fatigue and change in severity of fatigue in response to a nutrition intervention. ...PEM is a feature of ME/CFS and I would like to hear... how we could take this into account when measuring fatigue experience. For example, measuring fatigue experience over time may be more appropriate than a one off measure."

I am not up with what assessments, devices, etc are used in a research setting to measure level of unwellness or fatigue. Do we have a thread on this in the forum and/or consensus around this?

I note the self-report questionaires listed in https://me-pedia.org/wiki/Questionnaires_and_tools_to_assess_ME/CFS_symptoms_or_severity
 
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My first reaction to that request is to ask the dietician to please stop referring to measuring severity of symptoms in terms only of severity of fatigue.

To measure efficacy of an intervention we need questionnaires on all relevant symptoms and on activity levels, and objective measures of cognitive and physical functioning.

If a dietary intervention is aimed to address purely digestive issues, then that needs to be focused on, but also an overall rating of changes in symptom severity and functional capacity.

I think if they want a single rating scale to assess changes in illness severity, something like the Bell scale might give a useful indication.

Definitely need ongoing measures including ones such as wearable activity monitors, not one off measures.

We have lots of threads on this, and more measures are being developed.

Threads about development of questionnaires
https://www.s4me.info/threads/uk-me...in-nhs-me-cfs-specialist-services-2023.33221/
https://www.s4me.info/threads/norwa...ctioning-in-pwme-cfs-open-for-feedback.24995/

And an example of a discussion thread:
https://www.s4me.info/threads/scales-which-measure-disease-severity.11474/
 
RoseE said:
The dietician has asked "how feasible it is to measure people’s experience of fatigue and change in severity of fatigue in response to a nutrition intervention. ...PEM is a feature of ME/CFS and I would like to hear... how we could take this into account when measuring fatigue experience. For example, measuring fatigue experience over time may be more appropriate than a one off measure."

I am not up with what assessments, devices, etc are used in a research setting to measure level of unwellness or fatigue. Do we have a thread on this in the forum and/or consensus around this?

I note the self-report questionaires listed in https://me-pedia.org/wiki/Questionnaires_and_tools_to_assess_ME/CFS_symptoms_or_severity
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First of all, a big thumbs up for seeking feedback from the patient community :thumbup:

It's good they're aware of the need to measure repeatedly over time. It's unclear if they realise just how much time is needed to get reliable results. Many of us have months at a time when we're more or less bad for no discernible reason. Add to that the more short-term fluctuations. So researchers need to plan for repeat measures for a period prior to their intervention to get a reasonable sort of baseline to compare to, and then for quite a long period of time after their intervention.

It's also good they're aware of the importance of PEM in ME. However, I don't get the sense they fully understand PEM and the relationship to fatigue. They seem to be getting things back to front by talking about measuring PEM as part of the 'fatigue experience'. If anything it's the other way round, fatigue is part of PEM. And for many pwME fatigue is present, albeit at a lower level and together with a raft of other symptoms, all the time, also outside PEM episodes.

It's difficult to comment without knowing more about the specific proposal. Outcome measures have to make sense in the context of what is being studied. But generally speaking I would suggest forgetting all about measuring the 'fatigue experience'. Patients understand this term in a multitude of different ways ranging from applying it strictly to 'sleepy-tired' to using it as a short-hand to refer to a whole basket of different symptoms, which are different for each patient and even a single patient may use the term differently at different times. So trying to measure 'fatigue' becomes meaningless (plus it unhelpfully perpetuates the faulty notion that ME is all about fatigue).

Better to look for a global measure of function and/or total symptom burden, maybe just a simple visual-analogue scale going from I feel well to I feel completely crap, or from I can do stuff to I can't do a thing. Which particular symptoms are worst varies from patient to patient but there are two treatment outcomes which really matter to pwME (apart from an actual cure). One, a consistent reduction of total symptom burden at all times, at baseline as well as during PEM episodes. Two, an increase in the amount of activity we can do without triggering PEM. So that's something to keep at the forefront of mind.

Some important questions (and yes, I'm spelling out the bleeding obvious, it's just that we're so used to seeing the obvious ignored; however, some points here may also be new to researchers from outside the field - and if there are any other researchers interested in the ANZMES grants sneak-reading here: welcome :)) - back to the questions:

How are they going to make sure their participants have in fact ME? A few years ago rates of misdiagnosis (UK & AU studies) were around 50%. There aren't any more recent studies but misdiagnosis rates likely remain high.

Can their 'nutritional intervention' be blinded (e.g. blinding may be possible for a supplement but not for a special diet)? If blinding can't be done they'll need to think about suitable objective outcomes otherwise any findings will be too prone to bias to be useful. There was a suggestion they may possibly be using some sort of blood markers and that would be excellent especially if combined with a symptom burden/function assessment (e.g. Prof Tate found improved blood markers after mitoq but no improvement in symptoms).

What about controls, especially if it's not a randomised, double-blinded study?

How are they going to control for the impact of pacing? Variations in how well participants can pace throughout the study are likely to have a much larger effect on symptoms than anything nutritional.

They are specifically asking about measuring PEM. I'm not aware of any useful established outcome measures. There's the DSQ-PEM asking about frequency and severity of (somewhat poorly described) PEM symptoms but this ignores the big effects of pacing on frequency and severity of PEM symptoms. Which means it also doesn't address the issue of how much more a pwME can do without triggering PEM as a result of the intervention. This is currently a big gap (hopefully soon to be at least partly closed by the Norwegian function assessment questionnaire under development)

I'm assuming significant funding restraints that limit how ambitious the proposed study can be but if they can manage it, actimetry over an extended period of time is probably the best and most objective proxy for function we have at the moment. If that's not an option, questionnaires assessing function by asking about activities which can actually be undertaken without triggering PEM are a little better because a little less subjective than fatigue questionnaires (for the many problems with those please see the threads linked by @Trish).

Just reiterating, my comments are mostly general and not all of them will be relevant to this specific project. But hopefully they provide some food for thought for sharpening methodology for some future reader somewhere, sometime (ETA: ... and inspire to do a deep-dive into other threads discussing the issues raised above in more depth)
 
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Great points @Ravn. I just want to expand a bit on the nutrition intervention and pacing part :)
Ravn said:
Can their 'nutritional intervention' be blinded (e.g. blinding may be possible for a supplement but not for a special diet)? If blinding can't be done they'll need to think about suitable objective outcomes otherwise any findings will be too prone to bias to be useful. There was a suggestion they may possibly be using some sort of blood markers and that would be excellent especially if combined with a symptom burden/function assessment (e.g. Prof Tate found improved blood markers after mitoq but no improvement in symptoms).

What about controls, especially if it's not a randomised, double-blinded study?
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I think certain types of nutrition interventions can, if not be blinded at least be made obscure, even if they are whole diets. As long as there is a control group that gets a similar diet. Say if I wanted to look at the easy to digest diet we recommend to patients with digestive distress, compared with our regular dietary guidelines for healthy people: They are very similar and if a meal plan is made up for a month one could be mistook for the other. Same if one wants to look at different levels of macronutrients, unless it's going to the extreme the actual meal plans can look similar to that of a regular diet, and if looking at specific nutrients including more of a certain food in one meal plan than another is also easy to miss as long as there is variety in both.

Ravn said:
How are they going to control for the impact of pacing? Variations in how well participants can pace throughout the study are likely to have a much larger effect on symptoms than anything nutritional.
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I am lucky enough to have someone who can prepare food for me when I'm unable to cook myself, but not everyone are. If one gets PEM from trying to change the diet that is different from the diet itself causing PEM. Though obviously if an intervention cannot be safely implemented it's not going to work even if it might have been beneficial if possible to implement.

If it is a whole diet intervention, changing the diet can itself be an exertion, both physical and cognitive. How adaptable is the diet to pacing? Must everything be made from scratch, or is it possible to get ready meals that adhere to the intervention? How is the cognitive load on patients to change their diet (there's a difference between getting a list of what not to eat and some general principles, vs a shopping list together with a full meal plan)? Are there special foods that must be sourced from speciality stores (require more exertion when shopping)? Does the diet contain foods or preparation methods that can trigger sensory sensitivities (strong smells or sounds)? How about digestive issues that may be increased when someone is experiencing PEM?

Another thing I think is important is that dietary interventions, just as psychology ones, can be used to argue patients just have to pull themselves together/it's the patient's own fault for eating "wrong". And I think it is useful to acknowledge this and be clear it is not the case.
 
Excellent points @Trish, @Ravn and @Midnattsol.

As well as ensuring that participants do in fact have ME/CFS, it might be necessary to have even more detailed selection criteria. For example, not all people with ME/CFS have dietary sensitivities, but some do. Not all people with ME/CFS have gut issues at a particular time, but some do. Depending on what is being tested, there is likely to be some self-selection for trial participation. People with certain food sensitivities may not want to be involved in a trial. Some people will want to continue taking their usual supplements. The result is that it will be really important to characterise the participants well, match trial arms and to not extrapolate any findings beyond the sample characteristics.

For sure, actimetry is a desirable way of measuring the impact of a treatment. Whatever outcome measure is used, I want to endorse the importance of conducting the trial over an extended period of time. That is probably 3 months at least, and ideally six months. Such a long period of time has implications for the type of dietary intervention that will be possible for a given budget, and for the methods of outcome measurement.

I guess dieticians all understand that having a dietary intervention trial that runs over the Christmas period is asking for trouble. They might not be aware that things like school holiday and exam timings can have a big impact on the health of those young people with ME/CFS who are still trying to attend some school or university.

Midnattsol said:
Another thing I think is important is that dietary interventions, just as psychology ones, can be used to argue patients just have to pull themselves together/it's the patient's own fault for eating "wrong". And I think it is useful to acknowledge this and be clear it is not the case.
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Indeed. I think we would know if typical healthy diets made a significant difference to ME/CFS. I am sure most people try eating very well at some point in their illness in an effort to cure themselves. So, I wouldn't prioritise something as obvious as testing a Mediterranean or whole food diet when funds are scarce. I guess a trial that showed that a rigorously healthy diet makes virtually no difference to ME/CFS symptoms could be useful, but the researcher would have to accept the high likelihood of the negative result.

There are interesting diet-related questions though. A lot of people with ME/CFS favour a low carbohydrate diet, and it would be useful to have a proper test of a healthy ketogenic diet. As @Midnattsol said, there's the question of whether easy to chew, easy to digest meals can help people with severe ME/CFS. There's the question of whether a high salt, high water diet helps orthostatic intolerance.

With respect to blood markers, we've seen way too many studies measuring the usual panel of cytokines and reporting that there's nothing much to see. So, I'd hope that any metabolite or protein that is tested would have been selected for a reason that relates to a hypothesis beyond a vague idea about inflammation. It may not have to be blood sampling - urine and saliva might allow for more frequent sampling that evens out fluctuations.

One outcome that I'd like to see for a lot of treatment trials is a followup assessment of how many people have continued with the intervention once the trial is over, when there was no subsidised treatment?
 
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Agree with all the above, but the question:

"how feasible it is to measure people’s experience of fatigue and change in severity of fatigue in response to a nutrition intervention. .. ?"

can't be answered with any precision without the foundational hypothesis for the trial of a "nutrition intervention" being made explicit, indeed without the hypothesis to be tested being clearly stated, we are in the same territory as CBT and GET, where trials are based on a vague handwavy or prejudiced notions of pathology. Why 'should' a nutrition intervention be of use to an ME/CFS patient ? Is it proposed that ME/CFS involves some specific digestive dysfunction ? Are ME/CFS patients at specific risk of malnutrition ? What is that is hypothesised is the role of nutrition/malnutrition in ME/CFS that is specific to the single symptom of 'fatigue' ?

And what of fundamental versus comorbid definitions ? Is it considered that for example, IBS symptoms are fundamental to ME/CFS pathology or is IBS to be considered as a common co-morbidity such that any study would properly be called a "nutrition intervention in ME/CFS patients with IBS ? These are important considerations in the formulation of a 'nutritional hypothesis' of ME/CFS pathology.

It's good that researchers are thinking about 'how' to research ME/CFS, but they really need to start with 'why' if they are not repeat the dross of the past.
 
CRG said:
Are ME/CFS patients at specific risk of malnutrition?
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Patients that are housebound (even only periodically), and/or have cognitive or muscular impairments that made it hard to shop/prepare foods/eat, and/or have nausea or other symptoms that can reduce food intake are generally considered "at risk of malnutrition" and should be screened based on the criteria used in Norway at least. I'd say that could easily be applied to many pwME. I'm "only" mild/moderate but would be at risk of malnutrition when in PEM.
 
Actimetry and upright time measurement seem essential because if a nutritional intervention involves cooking, this will increase participants’ activity and potentially cause PEM. Meal planning may also induce PEM just because of cognitive exertion.

Conversely, if ready-made foods or drinks (such as fortified drinks) are trialed, this might save patients energy but it will be difficult to tell if any improvement comes from this or the nutritional changes themselves.
 
There's also the problem with significant diet changes that you can't untangle what it is about the diet that caused any observed changes. For example someone might improve on a keto or low Fodmap diet because it involves eliminating something they are sensitive to such as wheat, not because of the rest of the changes.
 
An interesting question. A lot of good points have been made.

My initial reaction is that there should be a primary outcome measure that is based on how many people show a specified improvement on a scale as suggested by Ravn: (a simple visual-analogue scale going from I feel well to I feel completely crap, or from I can do stuff to I can't do a thing.) and ALSO show a specified improvement on actimetry at 3 months. In addition lots of other symptoms can be logged, but not for statistical analysis - to see what changes if the primary measure comes out with a result.

Diets cannot be blinded easily but the obvious option, as I think Midnattsol suggested, is to compare perhaps four diets that stratify certain elements in such a way that it is very difficult for patients to know which if any diet is supposed to be the helpful one. This also relates to the point raised as to what the researcher thinks is worth testing and why.

I can see a difficulty if the researcher wants to suggest diets that require explanations of rationale - because that is an ideal way to introduce bias. I think the diets should be offered without a rationale - just saying that the researcher is interest to know if any of these four diets helps, with no expectations.

The dietary changes should be very simple, as Trish implies. Not adding a range of supplements or lots of restrictions, any of which might be responsible for an effect.

I can think of all sorts of caveats and complications to this. It is hard to know what to suggest without knowing what the researcher's rationale is - whether focused on one specific diet or just wanting to know if diet makes a difference.
 
Trish said:
There's also the problem with significant diet changes that you can't untangle what it is about the diet that caused any observed changes. For example someone might improve on a keto or low Fodmap diet because it involves eliminating something they are sensitive to such as wheat, not because of the rest of the changes.
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This is something that gets too little attention. There are so many special diets that have elimination of food groups, but the elimination part is just a by-product of whatever other thing one wants to do with the diet and gets overlooked when explaining findings.

That said, meals and diets are complex, and it may not be possible to disentangle since there are interactions between foods, meals and the whole diet composition and we aren't able to analyse what components the food contain. And sometimes a compound that we have been able to isolate, or something that showed up in this one single study, is included in more and more studies because it is possible to say "look, it is in the litterature!" and then we don't try to include similar or new compounds even if that finding in the litterature might have been a fluke or is from a study that did not look at a comprehensive list of compounds.

A bit frustrating to read metabolomics studies where they don't provide a list of the 100+ metabolites that have been included, but perhaps only the top 15 different metabolites between groups. Makes it very hard to find larger patterns or compare across studies. What is in the top 15 in one study may "only" be in the top 30 in another, and thus not make it into the paper, so one loses the fact that a compound has been found in two studies to be different between groups (or maybe the findings go in opposite directions, which is also good to know).
 
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