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"Do doctors understand test results" - layperson's article explaining relative vs absolute risks etc

Discussion in 'Other Health News and Research' started by Dolphin, Jul 7, 2014.

  1. Dolphin

    Dolphin Senior Member

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    Explains the pros and cons of screening tests and how people can misjudge data.

    Similarly with mortality vs survival rates.
    Esther12, WillowJ, MeSci and 3 others like this.
  2. Valentijn

    Valentijn Activity Level: 3

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    On the flip side, in psychobabble they often mention the risk of "iatrogenic harm" caused by the testing itself, in essence recommending minimal testing. They presume additional testing won't help us at all and suggest that investigating our symptoms has some chance of causing physical or psychological harm (in the form of making us think we have a biological illness).

    Yet I doubt any of them could say what the odds are of iatrogenic harm, versus the harm of a missed diagnosis or missing the detection of some other treatable abnormality, much less that any have bothered conducting any research on the subject.

    Maybe some doctors are just math averse in general, and prefer to rely on their "expert" random guesses.
    Last edited: Jul 8, 2014
  3. xchocoholic

    xchocoholic Senior Member

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    I love the way these articles tell patients how to talk to doctors.
    Now there's a statistic ...lol. tc .. x
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  4. PennyIA

    PennyIA Senior Member

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    I did like that set of paragraphs as well. Suggestions as to how to act deferentially and non-confrontationally. <sarcasm> Because, of course, the ego of the doctor needs to get catered to.</sarcasm>

    I did like the ending about how you do need to ask questions instead of assuming that they are a God.

    In my experience, if it's not bulleted out in uptodate.com in a form that can be read in about 20 seconds? It's not something my doctor will know or will look beyond... another reason I need to switch to a new doctor.
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  5. anciendaze

    anciendaze Senior Member

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    I've already commented elsewhere on what Gigerenzer found when he talked about risk management at Goldman-Sachs after the 2007 crash.

    If well-paid people managing your money can claim they were hit by a series of 25 sigma events in a period of days, what does that tell you about the financial industry? Many of these people have far more exposure to mathematics than your average doctor.

    There is a cynical viewpoint which explains a great deal of this. Normal in the financial industry means "we are making lots of money". Anything else is a catastrophe "nobody could have predicted" which requires government intervention.

    This also explains the lack of response to "evidence-based medicine" showing that screening for prostate cancer over 20 years produced no drop in mortality rates, and did result in significant unnecessary surgery.

    The key insight involves mathematics doctors demonstrably do understand: "if you operate, you will be paid thousands of dollars."
    Last edited: Jul 8, 2014
  6. Cheshire

    Cheshire Senior Member

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    Very interesting, thank you!


    The first example with breast cancer reminds me of that:


    What causes chronic fatigue syndrome? Peter D White

    http://www.bmj.com/content/bmj/329/7472/928.full.pdf



    So one could think an inactive childhood may be a relevant factor in most CFS cases.



    But nevertheless, the emphasis has been put by White and Co. to that inactive childhood factor, fitting so well to their preconceived ideas.


    (Emphasis mine)
    Last edited: Jul 7, 2014
  7. Dolphin

    Dolphin Senior Member

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    That study (on which White commented) led to some headlines like "lazy kids more likely to get M.E."
  8. PennyIA

    PennyIA Senior Member

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    Of course, no one would have bothered to look at the next level - which is... why the kids might have been less active. I met a woman at a fibromyalgia support group session who stated "I never knew why I had less energy than my friends."... and now that I think about it. I had spurts of energy, but nothing sustainable even as a youth. So of course, I gravitated to less strenous activities...

    I do hate how easy it is to dismiss our condition as 'laziness' out of one side of their mouth and 'overdoing' it for the overachievers out the other side of their mouths... instead of realizing that it's striking down people regardless of their activity levels. Just because they only get tired after overdoing it doesn't mean they are actually ill. And if we were just 'tired' after overdoing it, we wouldn't be trying so hard to find a medical problem at the root of all of this.

    But it comes down to the types of tests and the spin on the numbers. Having worked for multiple financial companies and in politics - the truth is... if you want to scare people to the point of action - you can make the numbers sound worse than they are. Statistics at the root don't lie (well, bad data in might), but how you spin it? You can come up with the emphasis falling where you want it to quite easily.
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  9. MeSci

    MeSci ME/CFS since 1995; activity level 6

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    Hmm...own spare-time sporting activity as a child: tennis, high-jump (in garden), throwing and catching ball, kicking a ball around, swimming, beach cricket, running, cycling, canoeing, and if you count them: climbing trees and even electricity pylons :eek:, lots of walking and generally being a tomboy. Probably missed some things out - it's a long time ago.

    Also represented school at running and high-jump. Very inactive... o_O and this seems quite typical from messages I see from other sufferers.
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  10. MeSci

    MeSci ME/CFS since 1995; activity level 6

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    Funny you should say that. I too often had difficulty sustaining activity, especially swimming, as I ran out of energy. For most activities I compensated for this with sheer willpower, but with swimming I couldn't. I had extreme difficulty even swimming a length and thought that the problem might be a poor breathing technique, but now I wonder...
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  11. WillowJ

    WillowJ Senior Member

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    my friend who didn't do sports or PE as a child, found a heart condition as an adult.

    I used to do sports (not usually organized), but I did get dizzy eventually. I couldn't swim well, though.
  12. NK17

    NK17 Senior Member

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    To which PWME and their true doctors should reply: "Crazy corrupted doctors more likely to resorts solely and abundantly to psychological factors to explain complex multi-systemic chronic diseases."
  13. NK17

    NK17 Senior Member

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    And that is called PROPAGANDA, which is the opposite of pure science.
    golden likes this.
  14. Tired of being sick

    Tired of being sick Senior Member

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    [​IMG]
  15. Sean

    Sean Senior Member

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    Keeping up with and smoothly assimilating the latest self-contradicting psycho-explanatory incantation is so confusing.

    Not to mention fatiguing.

    So much easier just to pick one at random, and stick to it, evidence be damned. There are only a limited number of them, and like flares and hula hoops eventually your choice will cycle back into favour, and for a while at least you can claim vindication. Again.
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  16. Tired of being sick

    Tired of being sick Senior Member

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    Heart Rate is the weapon of choice in my arsenal..

    Throw a BPM reading of 166 after doing something as little as taking a shower, in his/her face..

    Then watch him/her scratch their head in disbelief......

    Only problem with this is, most of the time, this will be your last visit with him or her
    out of embarrassment or complexity, the Dr.will write you off....

    Dr.s do not like to think and it is only going to get worse....

    All you have to do is observe ANY very young Dr. in order to know
    how "puppetized" the CORPORATE Medicine/"Insurance industry" has become.....
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  17. biophile

    biophile Places I'd rather be.

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    The study by Viner & Hotopf (2004) reported that sedentary behaviour increased the risk and higher levels of physical activity decreased the risk. http://www.bmj.com/content/329/7472/941.full

    A later study by Harvey et al. (2008) including Hotopf found the opposite (see Table 4):
    http://www.cfids-cab.org/cfs-inform/Exercise/harvey.etal08.pdf

    "The increased levels of physical activity seen in those who later went on to report CFS was unexpected and is in contrast to a previous study that examined childhood exercise levels (24)."

    Those that went on to report a diagnosis of CFS continued to exercise more frequently than others, "even after they had begun to report increased levels of fatigue", so they speculated for 3 paragraphs that this association was consistent with or evidence for cognitive/behavioural/personality factors and patient reports about pushing too much.

    Looking at the authors involved, we know there is some mysterious arbitrary Goldilocks amount of exercise we are supposed to be doing, but as long as you have CFS you're not in this ad hoc applied Goldilocks zone and must be deviant.

    The earlier 2004 paper also cited a small case-control study which reported that high levels of exercise was a factor.
    http://www.ncbi.nlm.nih.gov/pubmed/8644768

    Two more large cohort studies also failed to find the association with premorbid activity and CFS:

    Clark et al. (2011) including Hotopf:
    http://bjp.rcpsych.org/content/199/4/323.long
    Premorbid childhood and adulthood physical activities not associated with CFS-like illness.

    Goodwin et al. (2011) including Hotopf:
    http://www.ncbi.nlm.nih.gov/pubmed/21458727
    Premorbid extremes of physical activity are not a risk marker for CFS/ME.

    I wouldn't take those larger cohort studies too seriously either, since none (?) medically evaluated their CFS cases (it was based on self-reported CFS), and the results are contradictory for a bunch of different factors.
    Last edited: Jul 7, 2014
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  18. MeSci

    MeSci ME/CFS since 1995; activity level 6

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    Won't they just put it down to stress, and maybe come up with some Freudian BS like an aversion to taking your clothes off or to water?
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  19. Valentijn

    Valentijn Activity Level: 3

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    The Cure for "anxiety" - laying down constantly :rofl:
    xchocoholic likes this.
  20. anciendaze

    anciendaze Senior Member

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    The really important number to monitor, for your own purposes, is heart rate recovery time. This automatically covers a number of problems which doctors typically consider separately. If you are deconditioned, this time will be unusually high, and it will drop as you improve. If you become sick, HR recovery will demonstrate a reduced capacity for aerobic exercise. Our problem is that not only will it be high to begin with, it will also remain high despite attempts at regular exercise.

    This is much easier to measure than a 2-day CPET. It will guide you to do the best you can tolerate in your current condition. The rule is simple: if HR recovery time increases, your exercise is too intense; if HR recovery time decreases, you are gaining ground within an exercise envelope you can tolerate. During an episode of PEM, HR excursions while exercising are greater and recovery will be slower. This is the only simple objective measure I know for PEM.

    If doctors measured this number, and believed it, there would be far less argument about PEM or PENE. Instead they insist that high HR and long recovery times mean we are not getting enough exercise, and talk about will power. If they were looking at the effect of exercise on HR recovery times, they could quickly recognize how narrow the gap is between our thresholds for useful exercise and PEM. For some the gap is non-existent.

    The problem here is that if they are confronted with numbers which violate their preconceptions they insist we must be lying or cheating. After all, how often are doctors' ideas proved wrong in medical journals?
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