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'CPET' -- An appropriate test for assessing/diagnosing ME/CFS?

Discussion in 'Diagnostic Guidelines and Laboratory Testing' started by alex3619, Jun 20, 2014.

  1. alex3619

    alex3619 Senior Member

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    Please note -- this post originally came from this thread -- "BMJ Rapid Response: Is Chronic Fatigue Syndrome a meme? 18 June 2014".

    I would agree were it not for the 2 day CPET. Everything is different now it has been independently confirmed as a valuable tool in assessing ME patients. We need to push this, HARD. Now I am not saying I think its the only test we need. I am saying its a start.

    Furthermore its an obvious test, and nearly every practicing doctor would have been taught it at medical school. THERE IS NO LONGER ANY EXCUSE for doctors to engage in psychobabble for ME. No excuse, anywhere, for any reason. There are indeed factors which led to this, which are keeping doctors in the dark. That is an entirely different issue.
    Last edited by a moderator: Jun 24, 2014
  2. Sasha

    Sasha Fine, thank you

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    I don't want to derail this thread with a discussion of the CPET but I think there would be dangers in pushing it as a diagnostic test. Just yesterday I read on the forums a post by a patient who had had a one-year relapse following such a test.

    I'd prefer to have the test pushed hard in the literature as demonstrating that ME is a genuine disease: I'd like to see a summary literature review published that would summarise the evidence in a handy form for doctors.
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  3. alex3619

    alex3619 Senior Member

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    The 2 day CPET is not currently a diagnostic test. It is currently concrete evidence of severe pathophysiology. That is what needs to be pushed.

    This test does indeed produce problems with some patients. More tests are on the way. A simple blood test would be ideal.

    However what the 2 day CPET shows is that there is a profound underlying energy deficit that can easily account for most symptoms, and in particular "fatigue". Psychobabble loses another disease to science, just like tuberculosis, diabetes, rheumatoid arthritis, Lupus, MS, gastric ulcers etc.

    Doctors ignoring this, even though there are issues with availability of testing, recommending testing, and who pays for it, as well as patient problems such as incapacity to do the test, are now at risk of legal sanction.

    Further, the principle of the CPET does not necessarily mandate exercise. A severe patient who is massively exerting just by sitting up in bed would probably show major physical problems using this test - a treadmill or bike should not be required. We need mobile testing equipment. Actual exercise, and the 2 day test, would be more for mild and perhaps moderate patients, with maybe some of the less severe patients.

    In any case there are markers now that are so strong that either a test or a composite test is likely at some point. Just when is still a matter of guesswork though.

    So I bring it back to this. Psychosomatic illness is just an idea, a meme, that suits certain ideologies, certain belief structures. Where is the objective evidence?

    ME and CFS(CCC) have the clear objective evidence, now, not at some point in the indefinite future. In just a few years it is likely the quality of that evidence will be as unassailable as anything in science.
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  4. Valentijn

    Valentijn Activity Level: 3

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    2-day CPET.
    Link please. Or is it your intent to just talk to reassure yourself, and not to persuade anyone about anything?
  5. kermit frogsquire

    kermit frogsquire *****

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    As I said the 2-day CPET test is abnormal in otherwise healthy bed rested people.

    As for the B-cell study - google it. The full paper is online. "Altered functional B cell subset populations in patients with chronic fatigue syndrome compared to healthy controls". Take any value and pretend you don't know if they are a patient or control - the study will not help differentiate because the 95% CI's overlap.

    The problem of the trial is one of extended tail distribution and statistics does not have a solution to such problems. Yes, we can play around with differences in "means" or "medians" and test their significance, but that is a pointless exercise with no real-world benefit because there is 100% overlap.
  6. Bob

    Bob

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  7. kermit frogsquire

    kermit frogsquire *****

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    Sedentary heathy controls are not a proxy for over-bedrested patients. Low blood volume, POTS, etc do not occur unless there is excessive bed rest. Sedentary just means "normal", not "athletic". However, studies using deliberately bedrested healthy controls have shown 2 day CPET testing to show the same effect as in ME.

    @chipmunk1 , physical symptoms do not mean physical illness, that is the problem. You need to talk to some psychiatrists or do some more research. Psychiatric conditions are very real and can produce very real symptoms.

    Furthermore, you know very well that there is not a single anecdote of recovery from the LP. If it was a single case, I would agree with you, but there are tens of thousands of such cases. Quite apart from those patients being "misdiagnosed" by "evil psychiatrists", they predominantly sought out a diagnosis from CFS speicialists such as Cheny, Klimas, Myhill, Bansal etc.
    Last edited: Jun 23, 2014
  8. Marco

    Marco Old blackguard

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    That would be a significant counterargument to the idea that PEM in ME/CFS is 'unique'. Can you point me to the research?
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  9. Valentijn

    Valentijn Activity Level: 3

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    Ah. It seems that you are expecting your statements to be taken at face-value. But your opinion disagrees with the published research which we are aware of. So if you have access to data which indicates groups other than ME patients perform much worse on day 2, you really need to link to it. Otherwise, please be aware that repeating something over and over does not make it come true.
    Maybe I'm missing something, but the range of values on the amounts of types of B-cells are not showing a lot of overlap. And the little overlap that there is certainly doesn't disprove that the differences are significant. It wouldn't be particularly useful for diagnosis at this point, but it still likely provides some clues regarding the biological nature of the disease itself.
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  10. Bob

    Bob

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  11. Bob

    Bob

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    Most CFS patients are not excessively bed rested. Most are moderately affected and participate in limited activities. And bed-bound patients don't attend clinics and go on cycle machines. (At least, I've yet to see a bed-bound patient on a cycle machine!) So the sedentary controls do not need to be excessively bed-rested.

    We're still waiting for you to source a single one of your assertions.
    Last edited: Jun 23, 2014
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  12. Marco

    Marco Old blackguard

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  13. Valentijn

    Valentijn Activity Level: 3

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    I'm pretty sure such data is mythical and doesn't actually exist. I guess we'll see!
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  14. Jonathan Edwards

    Jonathan Edwards Board Member

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    I would certainly like to see the reference for a study showing 2 day CPET results similar to ME/CFS in deliberately bed-rested normals. That would be important.
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  15. user9876

    user9876 Senior Member

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    There is a NASA study on prolonged bed rest and deconditioning I don't think they did a 2 day CPET test though.

    http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20030052739.pdf
  16. kermit frogsquire

    kermit frogsquire *****

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    Dear Professor Edwards, there isn't an exact replication study of "2 day CPET" per se, since that exact protocol is a new idea, Pacific Labs?. However, there is a body of literature on inflammatory markers 24h post-exercise in bed-rested subjects, both human and animal. These studies show convincingly that bed rest results in an inflammatory cascade, and fall in peak VO2, not otherwise seen in sedentary controls or normal subjects. Since the claim from Pacific Labs is a potentially important one, I don't think their conclusions are sound until deliberately bed rested healthy controls are tested accordingly.

    We also have to be very careful about the use of the term "VO2max". True VO2max is not easily achieved on exercise stress testing (even in healthy subjects) and often a surrogate term, "peak VO2 achieved" is substituted and the terms used interchangably. These are not the same measures at all. For example, if a person stopped exercising at a heart rate of 60% maximum for reasons of percieved effort, that would result is a dismal peak VO2 achieved, but that is not the actual physiological VO2max.

    Please examine the data from CFS exercising stress testing, in some of these studies 0% of subjects were willing/able to exercise to 85% maximum heart rate, some subjects achieving only 120bpm. Thus, as per the NY association of cardiologists guidelines, these exercise stress tests should be void. Again, I fear CFS specialists are blurring the lines here between a real physiological measure (VO2max), a completely different term (peak VO2) and a known phenomenom of cytokines and inflammatory markers that are seen in bed rested otherwise healthy controls.

    Let us also think logically about this for a moment, on the PACE trial the patients could only walk 300 metres in 6 minutes (1.8mph), yet on VO2max exercise stress testing one has to achieve at least 3.2mph at 6 minutes to reach a valid VO2max. And we also know from other CPET trials on CFS patients that they reach stage 5 and 14minutes on average - 4.2mph. So either those PACE trial patients were pretending to walk slowly, or the patients able to reach VO2max on CPET are completely different patients. Again, this whole area is a mess and I really have no confidence in any of the findings.

    To @chipmunk1 above, we all know there are different claimed incidences for this disease - Reeves claims 2-3%, Crawley UK claims 4.7%, Wessely/White claim 1-2%, Jason et al (CCC) claim a tenth of that 0.1-0.2%. Dr Esther Crawley further published data showing that 90% of her subjects recovered with nothing more than advice.

    Can't you see that your argument is circular, either the Canadian Guidelines are right, in which case 90% of those diagnosed with ME/CFS are making recoveries from false-belief, or they are wrong, and nothing you have said makes any sense whatsoever.

    What I have merely added to the above equation is that now the false-believers know what the Canadian Guidelines require, many of those people are becoming mixed in too, the CCC have therefore been rendered next to useless.

    - The patient knows what is required to get a diagnosis of ME/CFS
    - When asked "do you have post exertional malaise on the silly check box diagnosis scheme, the patient merely says to the "CFS specialist - yes doctor I do.

    This is the reality of CFS diagnosis today.
    Last edited: Jun 23, 2014
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  17. Mij

    Mij Senior Member

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    @kermit frogsquire "Sedentary heathy controls are not a proxy for over-bedrested patients. Low blood volume, POTS, etc do not occur unless there is excessive bed rest. Sedentary just means "normal", not "athletic". However, studies using deliberately bedrested healthy controls have shown 2 day CPET testing to show the same effect as in ME."

    Go to 25:00 min in this video. Here was an athletic ME patient who was not "bed rested" or sedentary non athletic type. She came back six months after her initial test after running marathons and her test results were a lot worse.

    A healthy control bed rested control would improve over time.

  18. kermit frogsquire

    kermit frogsquire *****

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    @Mij the video adds nothing to what I have said. Of course patients with organic disease under the label of ME/CFS are made worse by exercise - that has nothing to do with the shortcomings of a 2 day CPET test. I fail to see what your point is. Please read my post.
  19. Bob

    Bob

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    We are still waiting to see your evidence.

    But, you have failed to grasp the nature and implications of the two-day CPET anyway.
    The general capacity of individuals, or cohorts, is not relevant to the two-day CPET.
    What matters is a comparison of changes in capacity between cohorts over two days.

    In the two-day CPET studies, the changes in capacity of healthy sedentary individuals are of a different nature when compared to CFS patients on the second day of exercise.

    So your claim of a fall in peak VO2 in bed-rested individuals is irrelevant, unless you are claiming differences between cohorts in changes in exercise capacity over a two-day exercise text.

    (It seems obvious that a bed-rested healthy cohort would have a lower VO2 peak capacity than an active healthy cohort. But that's irrelevant to the two-day CPET study.)

    The irrelevance of your claim of a fall in peak VO2 in bed-rested individuals is further demonstrated by the latest two-day CPET study by Snell & colleagues because VO2 max fell in both groups (patients and controls) on the second day.

    Also, the results of the latest CPET study by Snell & colleagues were not particularly helpful in terms of VO2 peak.
    Instead the results of the ventilatory threshold work-load (VTWL) were of more interest.
    VO2 max results fell for both patients and controls on day-two, whereas the changes in VTWL were in opposite directions between groups.

    You can see the results here:
    http://forums.phoenixrising.me/inde...-paper-on-exercise-and-cfs.24050/#post-368197

    Further, 24 hour post-exercise inflammatory markers are not relevant to the two-day CPET test.

    And, as I've said already, the ME/CFS patients in the CPET study were not excessively bed-rested. They were semi-active patients.

    So all of your comments, above, are pretty irrelevant.

    Try reading the research your are attempting to critique.
    VO2 max was not central to the latest research by Dr Snell et al.
    http://forums.phoenixrising.me/index.php?threads/new-dr-snell-paper-on-exercise-and-cfs.24050/
    Last edited: Jun 23, 2014
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  20. alex3619

    alex3619 Senior Member

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    Is this an admission your earlier claims are false?

    These studies physhiologically measure what is going on. You seem to be referring to guidelines based on estimates.

    When has this been demonstrated for CFS? For ME? Do you have a reference?

    Where is your established empirical evidence for this? It is your argument that appears to be circular.

    Your entire argument rests on the presumption that a majority of patients are false believers. Yet you have presented no sound evidence this is the case.

    If you want to argue that diagnostic capacity is poor, then that is fair enough. We already know misdiagnosis rates in studies looking at community diagnosis can be higher than 70%, and that some claim 90% is more normal. Misdiagnosis does not however demonstrate lack of a problem, it means its not understood. Indeed, one of the reasons we know that diagnosis frequently fails is that other causes were found. Its not the case that they were proved to be faking or have false beliefs.

    Jumping to the conclusion that this means false beliefs or malingering is again, as I have pointed out before, the psychogenic fallacy.

    However this very point, a post exertional crash in energy production, is exactly what the 2 day CPET shows. Even if you could demonstrate this can happen in bedrest, which you have already admitted you cannot do, its irrelevant to the discussion. Further, the Light's research shows massive increases in some cytokines. With respect to post exertional issues, its irrelevant if this is diagnostic of the disorder, as it clearly demonstrates physiological issues.

    There is a difference between establishment of a definitive diagnosis, and establishment of widespread physiological problems.

    Given the data, any claim that most recover with talking, or most are faking, is unsubstantiated hype, and its disrespectful to the very sick.

    Without evidence your claims will be ignored by most.
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