Basic questions on terms and methodology used in clinical trials

[rvallee]

Related to the discussion on developing assessment tools for monitoring disease activity/ impact/ disability --

Why is the term 'psychometric' used for scales that measure also physical symptoms / symptom burden / disability?

Is a simple visual analog pain rating scale or a symptom diary also a psychometric tool?


See discussion on research for a new clinical assessment toolkit in NHS ME/CFS specialist services here.

And a paper mentioned there on developing a patient-reported-outcome-measure scale here.

I think that the ambiguity is used on purpose. Psychometric is specific to psychology, it shouldn't be used for this, not what it's meant for. The proper term would simply be questionnaires, or questionnaire-based, but that sounds less scientific than psychometric, which falsely creates the illusion that something is being measured, rather than evaluated, rated, or scored. It has "metric" in it and that sounds like science, where measuring accurately is extremely important.

When it's used with us, the excuse is that since we don't have actual symptoms, merely the perception of (and I know this is a common lie but I never privilege a lie), they are, in their mind, evaluating psychological issues, our perception of reality, our psychological state. So psychometric is a correct description of what they are doing, or at least why they are doing it, it just doesn't have much to do with us.

But they're not evaluating symptoms or anything like that, it's just part of the model to play with the ambiguity over the symptoms being "real", but since perception is "real", it's just as "real", even though when we use real what we mean is what's actually happening to us, not whatever someone else is perceiving from their perspective.

 

[Kitty]

From @MSEsperanza:

Further to the question about the term "outcome assessor" discussed above (starting here: https://www.s4me.info/threads/basic...gy-used-in-clinical-trials.30316/#post-445244 )

Quote from the Cochrane Handbook:


3. Who is the outcome assessor. The outcome assessor can be:

1. the participant, when the outcome is a participant-reported outcome such as pain, quality of life, or self-completed questionnaire;
2. the intervention provider, when the outcome is the result of a clinical examination, the occurrence of a clinical event or a therapeutic decision such as decision to offer a surgical intervention; or
3. an observer not directly involved in the intervention provided to the participant, such as an adjudication committee, or a health professional recording outcomes for inclusion in disease registries.

https://training.cochrane.org/handbook/current/chapter-08#section-8-6

For a summary on how the Cochrane handbook authors consider the question of which type of outcomes are used and who's outcome assessor relates to risk of bias see:

Table 8.6.a Considerations of risk of bias in measurement of the outcome for different types of outcomes

Use link above or see attachment.

 

[Kitty]

From @MSEsperanza:

A general (maybe dumb) question about epidemiology:

Are there chronic diseases that somehow protect from getting certain other diseases?

Or maybe disease specific treatment that will protect you from getting other diseases?

Sorry, not able to retrieve now, but recently saw a study on MS and Covid-19 claiming that infection had no influence on the disease -- no differences with respect to worsening of symptoms, disability, flare-ups etc.

Don't remember any details of the study, e.g. duration, so maybe results not valid, also don't remember if they asked for Post Covid. Just thought that they should have done or that Post Covid symptoms probably would have been recognized either as new symptoms or as worsening disability.

As the study reported zero significant differences, and if the study wasn't too poorly done, would that mean that in this study sample of people with MS no significant proportion got Post Covid?

If yes, that would be fewer people than healthy controls, wouldn't it?

So back to my first two questions -- is there any epidemiological or physiological evidence that having a disease like MS or Rheumatoid Arthritis or certain cancers makes it less likely that you get certain other diseases?

Or any treatments for chronic disease that make it less likely that you get other diseases?

Has that been explicitly asked/ studied yet?

And if that's the case, what could we learn from it for studying ME/CFS?

 

[Jonathan Edwards]

Having sickle cell trait/disease makes you less likely to suffer from malaria.
Glucose 6 phosphate dehydrogenase deficiency and thalassaemia are other ones.
People with ankylosing spondylitis are less likely to develop AIDS because of their HLA-B27.

 

[Nightsong]

Having sickle cell trait/disease makes you less likely to suffer from malaria.
Glucose 6 phosphate dehydrogenase deficiency and thalassaemia are other ones.
People with ankylosing spondylitis are less likely to develop AIDS because of their HLA-B27.

There was also a hypothesis that CFTR mutation (cystic fibrosis) could confer protection against both cholera and infection by tubercular mycobacteria, although I'm not sure if that panned out.