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Illness - The Placebo Effect

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eggshaped
862690.  Mon Nov 07, 2011 7:32 am Reply with quote

Dr Bob did a wonderful précis of Ben Goldacre's 'Bad Science' book - giving us more information than we could ever use on the placebo effect. I hope he doesn't mind me replicating it in this public forum, so that I can link to it in the research notes...


Daniel Moerman did an interesting study on the placebo effect. He examined results for a variety of clinical trials for gastric ulcer medication. All the clinical trials compared a drug to a placebo to investigate the efficacy of the drug. What Moerman did, though, was to ignore all the results for the actual medication, and just compared how the placebo arms of each trial compared to each other. In particular he found that patients who were given 4 sugar pills to take each day showed a greater improvement of symptoms that patients who were given only 2 sugar pills per day. So, despite the fact that all these patients were not being given any active ingredient at all, the ones who thought they were getting more did better.

Similarly, Braithwaite and Cooper (1981) examined the effect of aspirin against a placebo for treating headache. Patients were randomly assigned either aspirin or a placebo, but also the pills came in either a blank, plain box, or a flashy, brand name box. Unsurprisingly, aspirin worked better than the placebo, but both the aspirin and the placebo worked better if it came in the flashy, brand-name box.

Another US study examining treating pain from electric shocks found that exactly the same medication worked better at relieving pain for the patients who were told the drug cost $2.50 compared with the patients who were told the (exact same) drug only cost 50c.

Colour also plays a role in the placebo effect. Blackwell (1972) experimented on college students giving them sugar pills that were coloured either pink or blue. The students were randomly assigned a colour, and also randomly told that the pill was either a stimulant or a sedative. Results showed that the pink sugar pills worked better as a stimulant, while the blue sugar pills worked better as a sedative. (The same study also confirmed Moerman's findings in that they found that two sugar pills produced a greater effect than one sugar pill)

Also important is the route of administration. Three separate trials studied the effect of placebo on blood pressure, headaches, and post-operative pain. Each of them found that a saline injection produced much better results than a sugar pill, presumably because an injection is a much more dramatic intervention so the patient expects it to work better.

A BMJ article also studied how the ritual of prescription affects the placebo. In a study on arm pain, patients were either given a simple sugar pill, or they were given a placebo delivered as part of a long and elaborate ritual based on acupuncture. Both sets of patients received a placebo, but the ones with the elaborate ritual showed a greater improvement of symptoms. This, of course, ties in with the greater ritual and interaction of complementary therapies like homeopathy compared with the rather limited amount of time a GP gets to treat their patients.

Thomas (1987) also showed that a placebo diagnosis can be extremely useful. He studied patients who presented to their GP with no clear symptoms or simple diagnosis. Half of the patients were told by their GP "I can't be certain what's wrong with you" and sent on their way. After two weeks, only 39% of them had got better. The other half were given a firm (if bogus) diagnosis by the GP and told that their symptoms would improve quickly. Two weeks later 64% of this group had got better.

This raises an interesting point. In the old days, people were happy to accept that "doctor knows best" and just accepted what they were told. These days it's generally accepted that the patient should be fully informed about their treatment, but that leaves some people unsure of what's wrong with them if the doctor can't diagnose the problem. By contrast, alternative therapists will happily bang on about energies, vibrations, chakras, and all sorts of other bullshit. In that way, they're effectively blinding their patient with "science" in the same way as the most patronising Victorian doctor. The popularity of alternative therapy shows that there's still a market for this kind of approach.

Gracely (1985) also showed that the attitude of the doctor affects the placebo effect. In a rather complicated experiment that may be hard to summarise for one of Stephen's notes, he took a bunch of patients requiring pain relief and divided them into two groups (say A and B). Each of the two groups were then further divided into three groups (A1, A2, A3, B1, B2, B3). A1 and B1 were given an effective painkiller, A2 and B2 were given a placebo, and A3 and B3 were given a opiate receptor blocker which would actually make the pain worse.

The difference between groups A and B were the doctors. Doctors treating group A were told the truth about the drugs. Although the actual treatment was double blinded so that nobody knew who was getting which drug, doctors treating group A knew that they had a 1-in-3 chance that they were administering a powerful painkiller. Doctors treating group B were only told about the placebo and the opiate receptor blocker, so they thought they were, at best, making no difference and, in 50% of cases, making things worse. Sure enough, despite receiving the same treatment, patients in group A experienced significantly less pain overall than patients in group B, even though the doctors were forbidden from telling the patients anything about the treatment they were receiving. It seems that the attitude of the doctors must have been communicated subconsciously, presumably through body language.

Sham operations have also been shown to be effective. A study of patients suffering knee pain showed that a placebo operation, where the surgeon makes an incision, but then just stands around for a while, doesn't actually do anything, and then sews up the incision again, produced real improvements in the patients' symptoms.

But it's not just pain relief that placebos help with. A Swedish study in the late 1990s showed that heart patients that had been fitted with pacemakers that had not been activated still showed an improvement in symptoms. Sham angioplasty has been shown to be almost as effective as a real operation, and sham heart operations have been shown to give real improvements to angina patients. Given that angina is a physiological condition caused by constriction of the blood vessels to the heart, this is a pretty astounding result.

Another study examined "room attendants" in US hotels. They were split into two groups. One group were told that cleaning hotel rooms was good exercise and given an elaborate explanation why this was the case. The other group were simply told nothing. After four weeks, the "informed" group showed a significant decrease in weight, body fat, waist-to-hip ratio, and BMI, despite reporting the same levels of activity as the group that had been told nothing.

Finally the book mentions Quesalid, who was a First Nations shaman living in Canada. Originally, Quesalid suspected that shamanism was bogus, so he decided to train as a shaman in order to expose the lie to the world. He found a shaman who took him on and taught him all the tricks of the trade. One of which was the "tuft" trick. In this, the shaman hides a piece of tuft in his mouth. He then places his lips against the patient and sucks hard. In the meantime he sneakily bites his own lip to make himself bleed. Then the shaman produces the blood-soaked piece of tuft and pretends it's diseased tissue that has been magically removed from the patient without breaking the skin.

Quesalid intended to expose the fraud when he had finished his training. However, as part of his training, he was required to treat a real patient. He duly performed the "tuft" trick, and was amazed to discover that the patient made a full recovery. This so affected his view of the world that he went on to have a long and productive career as a shaman and a healer despite knowing full well that all he was doing was placebo "operations" and sleight-of-hand tricks.

 
Spud McLaren
864036.  Sat Nov 12, 2011 3:12 pm Reply with quote

eggshaped wrote:
By contrast, alternative therapists will happily bang on about energies, vibrations, chakras, and all sorts of other bullshit.
Y'know, this (the full post above, I mean, not just the bit I've quoted from it) makes me wonder, despite all the research - if modern medicine isn't coming up with the goods for a hefty percentage of the time and "alternatives" are catching up - whether modern medicine isn't bullshit a lot of the time too. Or else, maybe alternatives aren't.

Not that I'm advocating a return to rubbing a mushroom with salt and throwing it down your neighbour's well - or at least, not for healing reasons. But the research does seem to suggest that your recovery, at least in cases where surgical intervention isn't needed, depends more on the quality and quantity of time your practicioner gives you than on the substances he gives you.

Edited for daft typo.


Last edited by Spud McLaren on Sat Nov 12, 2011 6:54 pm; edited 1 time in total

 
aTao
864059.  Sat Nov 12, 2011 6:01 pm Reply with quote

Spud McLaren wrote:

Not that I'm advocating a return to rubbing a mushroom with salt and throwing it down your neighbour's well - or at least, not for healing reasons.


Why not? The research referenced above shows that it does work, especially if it is a very expensive mushroom in a pretty box prescribed by someone with letters after their name.

 
aTao
864061.  Sat Nov 12, 2011 6:05 pm Reply with quote

Also (darned if I can trawl through for a reference) an experiment showed that placebo can improve a medical condition even if its declared as a placebo.
The test took 2 groups, 1 was told "heres a placebo, its just a sugar pill", the other group was told "come back in 4 weeks, we can treat you then".

 
Spud McLaren
864065.  Sat Nov 12, 2011 6:42 pm Reply with quote

aTao wrote:
Spud McLaren wrote:

Not that I'm advocating a return to rubbing a mushroom with salt and throwing it down your neighbour's well - or at least, not for healing reasons.
Why not? The research referenced above shows that it does work, especially if it is a very expensive mushroom in a pretty box prescribed by someone with letters after their name.
It's a point you have there...

 
Leith
864075.  Sat Nov 12, 2011 7:30 pm Reply with quote

aTao wrote:
Also (darned if I can trawl through for a reference) an experiment showed that placebo can improve a medical condition even if its declared as a placebo.

I imagine that even if that wasn't originally true, it could be made so if repeated often enough - thus providing a brilliant solution to the ethical problem of the deception involved in administering placebos.

 
PDR
864090.  Sat Nov 12, 2011 9:01 pm Reply with quote

I wonder if there is a connection with the Hawthorne Effect? Is that a socio-economic or industrial placebo?

PDR

 
plach
864240.  Sun Nov 13, 2011 3:00 pm Reply with quote

Leith said:

.
Quote:
..thus providing a brilliant solution to the ethical problem of the deception involved in administering placebos.


Although I still write freelance part-time, my day job that pays the rent is as a research coordinator in clinical trials. Although we have many different types of trials, any that involve the use of a placebo require full disclosure. Any patient in such a trial is well aware that they are receiving either active drug or a placebo.

No reputable clinical trial would 'deceive' their participants like that.

 
Leith
864241.  Sun Nov 13, 2011 3:48 pm Reply with quote

I don't imagine otherwise. In case it wasn't clear, I was just noting that the general principle of administering placebos as a treatment typically involves an element of deception, not making any assertions relating to the conduct of any particular trial or medical practice.

 
aTao
864274.  Sun Nov 13, 2011 6:51 pm Reply with quote

aTao wrote:
Also (darned if I can trawl through for a reference) an experiment showed that placebo can improve a medical condition even if its declared as a placebo.
The test took 2 groups, 1 was told "heres a placebo, its just a sugar pill", the other group was told "come back in 4 weeks, we can treat you then".


Found it: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0015591

 
plach
864311.  Sun Nov 13, 2011 9:45 pm Reply with quote

Thanks for clarifying, although I'm not sure if I would use the word deception at all.

Using a placebo vs. active drug is just a method to determine the effect of the treatment. After all, if you are applying for a drug to market you need to prove that it works better than an empty pill or nothing at all.

The psychological effects of any pill or treatment (as already mentioned here) can make a difference not only in patient perception but their physical response. So the drug with the active ingredient must show that their effect was even better than an empty product (and it's possible psychological impacts).

I work in the data collection aspect (not analysis). However it is fascinating to listen to patient's theories on why they think they are (or are not) on the placebo.

Just for the record (because it matters to me) I don't work for any pharmaceutical company. I work for a large group of cardiologists that have a small department for clinical research. I work on worldwide trials but the cardiologists choose the patients--and sign my paycheck. Our patients are all volunteers, none are paid to participate.

 

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