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Measuring fatigue. Discussion of alternatives to questionnaires
I get the impression that a key problem we're facing is that we don't have a good measure of 'fatigue' yet people who've made their careers as experts in 'fatigue' want to try to overlook that.
Is anyone aware of any literature on that sort of long-term 'Garden of Forking Paths', with researchers choosing primary outcomes for later trials on the basis of what they can get as positive in earlier trials rather than on the basis of what is a the more useful outcome for providing patients with useful information about treatment efficacy?
Perhaps we should try make a "fatigue" measure ourselves?
I agree that this is what needs focussing on.
There is even doubt that, as a symptom, the target should be called fatigue.
So I am increasingly of the view that what we want to measure is what Esperanza has called motor fatigue. And the need is to measure a specific pattern of motor fatigue X, that is characteristic of ME, or maybe patterns X and Y and even Z that are patterns characteristic of subsets of ME. Whether the symptom is best called fatigue does not matter so much. X or Y would be objective indicators of whatever symptomatology was responsible for the impact on active life in ME.
It would be the equivalent of respiratory function tests for asthma. Nobody assesses asthma by asking how wheezy someone is. They measure air volumes shifted. And to confirm that the problem is truly asthma, which is reversible from episode to episode, patients are asked to measure their own volumes on a daily basis.
This is of course where the accelerometers come in, but they need to be used intelligently, not just as a crude index of the number of wiggles. Off hand I can think of about a dozen PWME whose movement patterns I am familiar with. They will differ from those of healthy people in a variety of specific respects even if the total number of wiggles is not different. I am pretty sure this can be measured, but it requires intelligence in interpretation.
I do not know of literature on Garden Paths as a problem but the reality of the phenomenon is very familiar to any rheumatologist. Around 1970 the first new drug to have an immediate effect on joint pain and swelling was developed using what we now consider standard trial methods - ibuprofen. Jason et al. devised a scoring system that came to be known as DAS, based on counting numbers of swollen and tender joints. It was a useful system for anti-inflammatory drugs because it measured the rather limited benefits they gave. But it became embedded in scoring systems for all anti-rheumatics, to the extent that you could not make an application to the FDA for a new drug license without using it. This was a serious problem for the designers of collagenase inhibitors, which were intended to have no effect on symptoms but to protect tissue from damage. Another scoring system was the ACR improvement grading. ACR20 was for many years considered the end point, because a 20% improvement across various variables was considered good going. But when we started seeing ACR70 grades on a regular basis there was argument about the relevance of ACR20.
I guess what this illustrates is that picking outcome measures that look good is a regular part of treatment development and to some extent makes sense and is legitimate - but it can also distract away from more important goals. And if claims are made based on limited outcomes that are overblown, and negative findings suppressed, then things are going badly wrong.
I think a fatigue measure could be generated from accelerometers with good software. You would probably need ankle and wrist monitors at least, maybe both sides.
I find it very difficult to take in radio (and also video) stuff. I really appreciate that you take the time to make transcriptions so I can take the information in at my slow rate.
