Homoeopathy: is it all bad?
There has been much discussion in the blogosphere and the Twittersphere lately about homoeopathy, partly because of some Early Day Motions being put before the British parliament on the subject, and partly because of the BMA's vote against homoeopathy at their recent conference.
Now, this may come as a surprise to anyone who is familiar with my views on homoeopathy, but I'm going to mount a partial defence of it here.
Don't worry, I haven't completely taken leave of my senses. Let's start by being clear about the scientific basis of homoeopathy: it has none. There are some people who believe that diluting a substance until it is so dilute that there is absolutely none of the original substance left confers magical powers on the water you used for the dilution. Some may say that those people reject the paradigm of Popperian critical rationalism on which mainstream science is based, opting instead for a more sociologically based paradigm of individual existentialism, although personally, I prefer to say that they're just talking complete bollocks. If anyone isn't familiar with just how much bollocks the supposed science behind homoeopathy really is, Richard Dawkins has a nice video explanation of it here.
Much clinical research has been done on homoeopathy. Occasionally, people have found that it is effective, although that's mainly because of poor study design, for example lack of randomisation or blinding, that biases the study in favour of homoeopathy. Even with impeccable study design, if enough studies are done comparing homoeopathy with placebo, you would expect some to show benefits of homoeopathy just by chance, and supporters of homoeopathy may leap on those as evidence that homoeopathic magic potions really do have magical powers. However, if you look at the totality of the evidence (there's a good review here), the message is pretty clear: homoeopathy is no better than placebo. Not at all surprising really, because homoeopathic remedies are pharmacologically inert. They are placebos, so obviously they're no better than placebos.
So to repeat, homoeopathic remedies have no active substance in them, they have no scientific basis, and they are no better than placebo.
So why do I say I'm defending homoeopathy? Well, it may be no better than placebo, but of course it is also no worse than placebo, and placebo can actually be quite effective.
With many medical conditions, if you give a patient a placebo, the patient will get better. There are two quite distinct reasons why that may happen, and it's important to be aware of the difference. The first is that the patient may simply get better anyway because of the natural history of the disease. A good example would be the common cold. Most people who have a common cold recover within a few days. So, if you give patients with the common cold a placebo treatment, they will get better. But they would have done anyway, so this is not a true placebo effect. The true placebo effect is when a patient's expectation of benefit from treatment causes some physiological change which really does make them better. A good example of this would be patients with depression. Many patients with depression show dramatic improvements on placebo treatment, and indeed a recent paper in JAMA concluded that antidepressants offer little additional advantage over placebo for milder forms of the disorder.
Now, clearly giving placebo treatment is inappropriate if proven effective treatments exist. When homoeopaths offer to protect children against measles by giving homoeopathic treatments as an alternative to vaccination, that is mind-bogglingly irresponsible, and anyone who does so deserves the strongest condemnation, and possibly even locking up. Same goes for homoeopaths who offer to treat cancer homoeopathically as an alternative to potentially curative surgery.
But there are many conditions for which placebo is a reasonable treatment option. Mild depression is an obvious example, but there are many others. Plenty of gastrointestinal complaints have no obvious treatable cause, and yet can respond to placebo treatment. Placebo treatment has the advantage of being cheap and safe, so in those cases where the efficacy is as good as any conventional treatments (ie because no effective conventional treatments are available), you can make a very good case for prescribing it.
The trouble is that you get into very difficult ethical territory if you knowingly prescribe placebo. What do you say to the patient? It's hard to imagine that many patients would be impressed if you said "Here is a placebo pill. It is totally lacking in any medicinal properties, but if you believe in it, it might make you better." That, however, is the only truly honest thing that you can say when prescribing a placebo, but that honesty probably destroys any chance of the placebo effect working. Perhaps if you prescribe a placebo and tell the patient that it is a highly effective treatment then the patient will improve. However, that is dishonest. Trust is very important in the doctor-patient relationship, and it is not hard to see trust being very quickly destroyed by such practices.
Does homoeopathy offer a way round this problem? Homoeopathy is a placebo. It is also quite an effective placebo: the strength of the placebo effect depends on many factors, but one of them is the strength of the relationship between patient and healer. As homoeopaths typically spend far longer in consultation than conventional doctors, that relationship is stronger, which helps to maximise the placebo effect.
So is homoeopathy a reasonable way to prescribe placebos in those circumstances where placebos are justified? This is where it starts to get really tricky, and I'm honestly not sure exactly what I think about the ethics of this situation. Do you nicely circumvent the ethical problems normally inherent in prescribing placebo by calling a placebo a homoeopathic treatment? Or is that just as dishonest, given that we know that homoeopathic treatments really are placebos?
If you believe that telling patients who might benefit from placebo that a homoeopathic treatment may help them is ethical, then perhaps you can make a case for allowing it on the NHS after all.
What do you think? Let me know via the comments form below.