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Sham acupuncture is used as a control in scientific studies that test the efficacy of acupuncture in the treatment of various illness or disorders. In an ideal controlled study, subjects would not know whether they were getting true or sham acupuncture. If true acupuncture is not significantly more effective than sham acupuncture, then the effect of acupuncture is most likely due to conditioning and the placebo effect. If true acupuncture works significantly better than sham acupuncture, then that would indicate that some mechanism other than conditioning and the placebo effect is at work. It should be noted that "placebo effect" is a broad term that includes many non-interventional or invasive elements in medical treatment, including:
--suggestion by the healer
--patient beliefs in the competence of the healer and the method of healing
--patient expectancy and hope for recovery
--the healer's manner (showing attention, care, affection, sincerity, knowledge)
--the rituals and theater involved in the delivery of the treatment, including technical jargon, special uniforms, medical gadgetry, treatment room set-up, and the like
Other factors that might seem trivial, like the color of the treatment room or the color of the pill one is given, might affect patient expectancy.
Other factors (called "false impressions of placebo effects" by G. S. Kienle and H. Kiene) may also contribute to the difficulty in measuring just how much of the effectiveness of a treatment like acupuncture is due to the sticking of needles in acupoints according to some traditional or idiosyncratic formula. These "false placebos" may include:
--fluctuation of symptoms
--regression to the mean
--additional treatment (while in the study)
--patient politeness or subordination (the patient doesn't want to disappoint the healer)
--neurotic or psychotic misjudgment
It should be noted that placebo and false placebo factors are problems for researchers in all areas of medical science and are not restricted to those studying the effects of acupuncture.
Sometimes sham acupuncture is compared to another therapy, such as taking aspirin for back pain. If sham acupuncture is significantly more effective than the other therapy, it could well be because the subjects in the study have strong or weak expectancy of effectiveness based on their beliefs or past experience. The ritual of the sham acupuncture might contribute to its effectiveness. The effect of being randomly assigned to the acupuncture group (the subjects would be deceived and think they were getting true acupuncture or they would know that they might be getting true acupuncture) might increase the expectancy of effectiveness for the group. The disappointment of being randomly assigned to the aspirin group might decrease the expectancy of effectiveness in that group.
Sometimes a third group receiving another kind of treatment is used in acupuncture studies and is compared to true and sham acupuncture groups. Some very well designed studies have found that true and sham acupuncture are about equally effective for some treatments and better than a conventional, science-based treatment. Such results would indicate that placebo factors explain all or a good part of the effectiveness of acupuncture.
The ideal double-blind control in an acupuncture study would mimic acupuncture treatment, but would not insert needles into the patient and the acupuncturist would not know whether he or she was doing true or sham acupuncture. So far, no one has devised a way for an acupuncturist to deliver acupuncture without knowing either where she is inserting the needle or whether she is inserting the needle beneath the skin. This seems like an impossibility to me, but stranger things have happened.
In practice, sham acupuncture comes in several varieties. One type inserts needles into non-traditional sites but otherwise mimics traditional acupuncture. For this form of sham acupuncture to serve as a control, the subject must be ignorant of where the needles are traditionally stuck or blinded to where the needles are being stuck (by a screen and an anesthetic?).
Another type of sham acupuncture uses a method that prevents the needles from actually being inserted into the body, whether at traditional or non-traditional points. If the fakery takes place at traditional acupoints, there is no need to prevent the patient from seeing where the fakery is taking place. This method was used in a Swedish study on acupuncture as a treatment for nausea and is described as follows: "sham treatment ... involved an identical looking and feeling needle that retracted into the handle on contact with the skin." This method requires the subject to feel like he's been stuck even if he hasn't.
It is important that the patients in the sham group think they are getting true acupuncture. Ideally, the patients in the true acupuncture group wouldn't know whether they were getting true or sham acupuncture. It is equally important that the acupuncturist not indicate to the subjects in any way whether she is delivering true or sham acupuncture. Any acupuncturist delivering sham acupuncture has to be an actor and be careful not to provide the subjects with any information. Any study where the subjects can easily detect whether they are getting true acupuncture is a compromised study because it cannot measure the placebo effect unless, of course, one assumes that the only thing one is measuring when measuring the effectiveness of acupuncture are placebo effects.