Map of life expectancy at birth from Global Education Project.

Tuesday, January 29, 2013

Evidence based medicine

Sounds like a good idea, it's the right way to go but, it ain't easy.

Here's a problem I've been working on. Suppose you wanted to search all the relevant scientific literature and do a systematic review and metanalysis to figure out the best way to diagnose acute appendicitis. (I'll leave the definitions of unfamiliar terms in the preceding sentence for later; suffice it to say we'll be applying the best available methods for combing information from all of the good quality studies that have been done on the subject.) Then you can write a report and tell doctors how to do this. Fewer people get sent home only to have their appendix rupture; fewer people get surgery unnecessarily. Yeah!

Oh my gosh is it not nearly that easy. First of all, why are we trying to diagnose acute appendicitis in the first place? There are a lot of different tests you can use, but before you use any of them, you have to decide who to use them on. The facile answer is, people who show up at the ER with pain in the lower right quadrant of the abdomen. Then there are various other more specific clinical indicators that will raise or lower your suspicion that this really is acute appendicitis. But are we trying to diagnose appendicitis, or figure out whatever the reason might be that they have this symptom? If we go straight to question 1, maybe we're missing something else we ought to be thinking about.

And is this person a child, a woman (or for that matter a 14 year old girl) of reproductive age not known to be pregnant, a woman known to be pregnant, an adult male of [insert age category], or a very old person? How long have they had the pain? Every one of these variables means you're looking at a whole different kettle of fish.

Does the person have insurance that will pay for a CT scan or will they have to pay out of pocket -- or maybe the hospital will have to eat the cost. This is a medical emergency, potentially, so they have to treat you whether or not you can pay, but what does "treating" you mean? If you do have appendicitis, the cheapest thing to do (in hindsight), and the best from your point of view as well, is to go straight to surgery. On the other hand the totally cheapest thing to do, and the best from your point of view if you don't have appendicitis, is to send you home with advice to come back if it doesn't get better. But in either case, the wrong decision is likely to cost more and result in a much worse outcome.

You can always diagnose appendicitis, with almost perfect sensitivity and specificity, by opening up the abdomen and removing the appendix and having a pathologist look at it. But that's not really the question after all, is it? The question is, should I open the abdomen of this person with lower right quadrant pain. Maybe I'll find out they don't have appendicitis but there is some very good reason why I should have opened their abdomen. On the other hand, maybe they have an ectopic pregnancy or an ovarian tumor or colon cancer, and the wrong kind of surgeon is looking at it, who doesn't know what to do.

You can start with ultrasound, which has essentially no risk, but it's often equivocal. Then you can go to a CT scan, which does irradiate you with potentially some small long term risk, unless you're in early pregnancy in which case there may be greater risk to the fetus; you might also be less inclined to do a CT scan on a young child. If your hospital has an MRI scanner, there's no ionizing radiation but it's more expensive. And the hospital might not have one.

I could go on but you get the idea. You might be particularly averse to post-surgical pain, or you might not care so much. You might have known someone who died of a ruptured appendix so you're really anxious about it, or you might be happier to go home and wait. Whatever.

So . . . Doctors don't generally "know" what they're doing. They're just muddling through, hopefully for the best. As are we all.




4 comments:

Tony Mach said...

And that's not including the question to *why* people get acute appendicitis, and if there is something that could be changed to avoid it in some/many/most cases in the first place.

Having what might or might not be Beh├žet's disease, and having seen that many healthy problems of mine are very very strongly linked to the consumption of dairy and eggs, and seeing how much knowledge there is in the medical sciences about a possible link between such (skin) problems and dairy (Triolo et al 2002, Besu et al 2009, or Adebamowo et al 2004, 2006, 2008 is what I found, there might be a little but not much more, I guess), I think there is much more wrong in the medical sciences.

How much more quality of life I could have had, had one of the many skin doctors I have had seen simply told me a decade ago: Stop dairy for a month, and see if it helps. But no, the last doctor I told about my link between my dairy consumption and my symptoms got worried that I don't get enough calcium. It is almost an religious believe (for lack of better word) that milk is good, and that your health will suffer if you miss it. On what rational basis can well trained, scientifically inclined people maintain such an conclusion? Is there any other mammal that needs dairy its whole life? From a different species none the less! Are there any indications that the millions (billions?) of people who are lactose intolerant are suffering ill healthy because they don't consume milk?

So personally I think we will see (or so I hope) a change in medical and nutritional science as to what is considered healthy or unhealthy food, because the perspective what evolutionary novel food is (and what might plausibly cause disease), that perspective is almost totally missing. Though I have little hope that the change will be anything but slow. Why is it that evolution is an integral part of biology (cf. Dobzhansky), yet when it comes to nutritional science there is such an pre-scientific inertia (for lack of a better word) that fights teeth and nail against evolution?

Cervantes said...

I don't know that many nutritionists insist that people should eat dairy. Physicians are not necessarily well-trained in nutrition and may well have some misconceptions, however.

Chondon Chondro said...

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Homeopathic Vibrational Medicine, the 21st century Energetic approach for treating the body-mind constellation, based on ancient healing practices. Since 1984, Longevity has championed the growth and understanding of homeopathy, making these “user-friendly” combination remedies accessible and affordable. They are a valuable and safe alterative to OTC and prescription medicines for everyday ailments.
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Chondon Chondro said...

Longevity Pure Medicine
Homeopathic Vibrational Medicine, the 21st century Energetic approach for treating the body-mind constellation, based on ancient healing practices. Since 1984, Longevity has championed the growth and understanding of homeopathy, making these “user-friendly” combination remedies accessible and affordable. They are a valuable and safe alterative to OTC and prescription medicines for everyday ailments.
Cellular Meditation CD`s
to Dr R Brand
Viraxl
Immune Sweet