The Standing Invitation

Posts Tagged ‘Medicine

On the Relative Merits of AMPium

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“The problem with randomised controlled trials is that they don’t show how therapeutically useful homeopathy is.”

Statements like this elevate my blood pressure. They are often signify an oncoming attack against this wicked thing called Science. One encounters the word ‘homeophobia’: the denial by scientists that unknowable truths exist, motivated by the scientists’ fear that this would shatter their precious little calculations. (They are not so quick to offer a name for the phobia’s counterpart: the fear of being told you are not in fact a beautiful and unique snowflake endowed with mystical powers and the blood of Númenor flowing through your veins; in essence, the fear that there is such a thing as a wrong answer, and you might just have given it.)

Complaining about science in this way tends to be more about identity politics than a real issue of scientific methodology. Nevertheless, let’s take the above claim at its word, and make for it the best case that we can.

The assertion, minus the controversial H-word, is this:

“There exists, or might exist, such a treatment that has two properties: 1) it has some therapeutic value; and 2) it does so in a way that randomised controlled trials do not detect.”

This is the statement that proponents of randomised controlled trials (RCT) must disprove; and since the RCT is held as the gold standard, the burden of proof lies with its supporters.

Imagine a chemical called archibaldmatthewphillipsium or AMPium for short. This is a natural plant extract that has no medicinal value whatsoever – unless your name is Archibald Matthew Phillips. For this one lucky man, regular doses of archibaldmatthewphillipsium reduce the odds of cancer by 95%.

This is an extreme case. But it is well known that different people do react to some drugs differently, and personalised medicine is an important field. A patient with a certain illness will often be given a series of treatments in order to find out which one is best for him.

It so happens that AMPium is exactly the right treatment for Mr Phillips to take, and any systematic drug test that missed its value would let Mr Philips down. In this case, yes, a randomised controlled trial would not be the answer.

But this is unlikely. Nobody is that special. What is far more plausible is that what is 95% effective for Archibald Michael Phillips is, say, 90% effective for his immediate family; 80% for his extended family; 50% for people from a similar genetic or socioeconomic background, and so on, tailing away to a large proportion of the population for whom the drug is essentially valueless. Now we are back in the realms of ordinary statistics.

What should a doctor do when presented with a new patient? Of course the best thing to do would be to test him with every conceivable chemical compound, mystical trinket and shamanistic rite to find out exactly what the best treatment is best for him personally, and I would dearly love to see this happen. But this is impossible: it would take too long, and his symptoms might grow much worse before the tests were completed. This is a fact; not to acknowledge it is extremely irresponsible.

What we ask instead is: which group do we think he belongs in? The group for which treatment x is perfect? The group for which x is just an okay sort of treatment? Or the group for which it’s effectively useless?

Given our imperfect knowledge of the patient, we would base our decision on the sizes of the groups, and start him on the treatment that is most effective for the greatest number of people. And it is precisely that information that a randomised controlled trial provides.

 

REFERENCES

Jeanette Winterson OBE took the opposite view here. I advise you not to click. She doesn’t need the hit count.

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Written by The S I

October 15, 2011 at 11:59 pm

Thank Goodness!

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I’m away from the computer just now, so here’s an excellent essay by Daniel C Dennett describing how his life was saved by a heart operation – and what it really means when an atheist says “Thank goodness!

I have created a Facebook page for this blog, which those of you who are so inclined may wish to like.

Also, on yet another note, for times like this when I physically cannot get to a computer to update this place, I am thinking of recruiting some guest contributors so I have something to fall back on. If you’re interested in writing a post here on practically any topic, for a general audience and in under 500 words, drop me a comment and we’ll see what we can work out.

Written by The S I

October 11, 2011 at 11:59 pm