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Acupuncture and the Sham Control
As a former research scientist, I am always bemused as I prepare for the Microsystems class. Each year, I prowl around the internet, searching in PubMed and other scholarly sources for good data on the effects of the various microsystems and techniques that I cover during the semester. And each year, I run into the formidable puzzle of the sham control.
The sham control is, in theory, a great idea. A person responding to an acupuncture treatment might just be responding to the idea of an acupuncture treatment, a placebo effect. Naturally, we want to rule this out, so we need a control group for comparison. The best control group would think they received the same treatment, but actually didn’t, so the psychological factors would be the same. Any difference between the groupswould be best explained by the treatment itself.
It sounds so simple until you actually try to devise a good control. In many studies, the sham control is simply the placement of needles in places not thought to be acupuncture points. This presents problems. If you Google the phrase “sham acupuncture”, you will get a list of articles with headlines that proclaim “Acupuncture No Better Than Sham Acupuncture for [insert condition here].” A large percentage of the time, the sham acupuncture turns out to be insertion of needles in alleged non-points. But does the body really have non-points or irrelevant points? Probably not, given the demonstrable efficacy of ashi-point techniques, as well as various microsystems. Are we really surprised that so-called true acupuncture gives similar results to so-called sham acupuncture?
Other researchers have developed sham needles with blunt tips that retract into the shafts, rather like the fake hypodermic syringes used in movies. In 2006, Kaptchuk and colleagues even published a report in the British Medical Journal that actually pitted two placebo treatments against each other. Patients with arm pain reported more relief of symptoms with sham acupuncture using retractable needles than with treatments using a sugar pill. (Que placebo es mas macho?) But a 1998 study by Streitberger and Kleinbenz in Lancet reported that several patients tested with a sham needle experienced deqi sensation. This was given as evidence that the sham needle was convincing enough to be a valid placebo control. Couldn’t it also be evidence that the sham needle isn’t as sham as we might think?
So what’s an acupuncturist to do? If the study includes a drug control, then we have a little more to work with. Most mainstream drug treatments for a given condition have been tested against a drug placebo. So if the acupuncture works as well as or better than the drug, then by a kind of implied transitive property, we can conclude that it also probably works better than a placebo. That reasoning would make a hard-coreexperimentalist twitch (indeed, I can feel a twitching in the back of my own mind), but it’s logically sound, providing that we lace it with statistically-appropriate caveats. (We do of course have to remember Kaptchuk’s study and realize that acupuncture may just be a better placebo than a sugar pill.)
Bottom line is that as a practitioner, my chief goal is knowing what works. In my clinic, I’m less a scientist than an engineer. A scientist might study the molecular forces that keep the materials in a bridge coherent, but it’s the engineer who has to make darn sure the bridge will stay up. My treatments have to work, whether we understand the mechanism or not. I’m less interested in the sham control comparison than I am in the actual results reported. If improvements were obtained, then I know acupuncture does something good for the condition under consideration.
But what if it is all a placebo effect? I don’t think it is, because acupuncture works wonderfully on animals, and we don’t usually attribute a placebo effect to them. Secondly, I have found that acupuncture works pretty well on skeptics, who should, if anything, have an anti-placebo effect. But what if it is all a placebo effect? The human mind is probably the best healing tool we have available to us. Obviously I have to make sure my treatments are not just masking symptoms, which could be dangerous and irresponsible. Other than that, if the mechanism of acupuncture turns out to rely on evoking the ability of the patient’s mind and brain to regulate the body with a minimum of side effects, I have to say I think I’m okay with that.