Comparison of Diagnostic Criteria - discussion thread

I thought you were referring to ICD, rather than ICC. ICD is a coding system that does not in itself define diagnoses.
In itself, no. But it serves dual purposes. Always has. The US' national healthcare systems uses it for both. In some states, like mine, diagnosing and coding are synonymous for our health plan.
 
The only way for me to answer that is for you to spell it out.

I have never heard of 'diagnostic consensus criteria' but I am aware of diagnostic criteria that committees try to form a consensus on. Nobody else is obliged to take note of these criteria for clinical care. They are ways of pigeonholing patients that oversimplify clinical decision-making. They can be useful for standardising recruitment to research studies, although even there they tend ot be overused and research criteria are often different from 'clinical criteria'. They are probably also useful for social issues like disability payments.

In terms of clinical care the objective is to make as good a judgment as possible about the prognosis for a patient in terms of illness natural history and likely response to treatment. That judgment will depend on a range of factors and does not necessarily require diagnostic pigeonholing per se. An important part of it is assessment of probability, so there is a need to judge what will probably happen and what may possibly happen. It may be useful to explain this to a patient in terms of 'probable rheumatoid arthritis' but the clinical decision-making process is more complex and it may or may not matter that there is also a possible diagnosis of psoriatic arthritis.

So a set of diagnostic criteria that has a committee consensus is a Procrustean pigeonholing that can be dispensed with if you know the literature in the field well enough.

A set of good clinical guidelines is a recommendation of how best to manage people who have certain types of clinical problem. It may well be written as applying to a diagnostic grouping but to be any good it should cover the extent to which decisions are independent of diagnostic grouping. The UK NICE Guidelines for ME/CFS say that ME/CFS should be suspected if certain symptoms are present for a certain time. It does not give criteria for making a diagnosis. It rightly leaves that decision open. In essence it is a guideline for a group of people with chronic disabling symptoms associated with post-exertional malaise. It treats this as a homogeneous category perhaps more than it should but any such text will be a compromise. Arguably, chronic disabling fatigue without PEM should be covered as well because unless the reader already knows that prognosis is different for people with PEM they may not know whether or not to apply the guideline to a case they have to care for.
 
In contrast to NICE, the IOM explicitly called its 2015 ME/CFS criteria “diagnostic,” which sounds strange to me given the lack of validation.

A few years ago I talked to a rheumatologist (US), and they said that ME/CFS is a rare disease and that they have barely seen any cases. I suppose that if an American physician runs into such a patient and doesn’t dismiss them as having fibromyalgia, POTS, MCAS, or something else, they will likely check UpToDate, since it’s one of the most widely used clinical references. The ME/CFS chapter is written by Stephanie L. Grach and Stephen J. Gluckman. They write:

“We use the 2015 NAM clinical diagnostic criteria to diagnose ME/CFS.”
“A clinical diagnosis of ME/CFS requires fulfillment of these symptom-based diagnostic criteria and a limited evaluation to exclude underlying organic disease.”

My point is that, whether we like it or not, clinicians tend to take the shortest road. In fact, from what I’ve heard from patients with autoimmune diseases, rheumatologists often rely on criteria too—even though those criteria are classification rather than diagnostic.

Frankly, I’m not even sure that being diagnosed with ME/CFS nowadays is a virtue. In some cases, if it helps someone obtain disability benefits, then yes. In other cases, private doctors are happy to make a diagnosis, but they may exploit patients with concierge fees, ludicrously overpriced appointments, prescriptions for supplements and suggestions for exercise and SSRIs.
 
My point is that, whether we like it or not, clinicians tend to take the shortest road. In fact, from what I’ve heard from patients with autoimmune diseases, rheumatologists often rely on criteria too—even though those criteria are classification rather than diagnostic.

The people who write for UpToDate tend to be the same high profile physicians with constipated minds that sit on criteria committees. But also, I suspect quite a lot of rheumatologists and other physicians think they are using criteria in the clinic. Some of them actually do - I made that mistake early on my career thinking I was being precise. But there was an interesting study from John Kirwan years ago whch showed that physicians do not actually make decisions the way they say they do.

People are not very good at introspecting how they decide. The problem applies to ski instructors who claim they are telling you how they ski when 'bend the knees' is of no help at all. Cooks claim they get good results from certain methods when they probably do something quite different in practice. Physicians think they are using criteria.
 
But there was an interesting study from John Kirwan years ago whch showed that physicians do not actually make decisions the way they say they do.
Is it this?
I think it shows that there is a massive variability between how important the clinicians report a variable is, even though they end up rating the patients more or less the same.

 
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