Early ReportIntroducing a placebo needle into acupuncture research
Introduction
Acupuncture has long been used in the treatment of pain, although proof of its effects is uncertain. Since no satisfactory placebo to acupuncture has previously been developed,1, 2, 3 it has not been possible to differentiate the effects of the therapeutic setting from specific effects of acupuncture needling. To measure such effects, a placebo method of needling with the same psychological impact as actual needling is required. Comparison of acupuncture with other treatments or transdermal electric nervous stimulation are unsatisfactory as the setting is largely different from acupuncture. Pricking or scratching the skin with a blunt needle4, 5 can only be applied, blind, on the back. In most studies no attempt has been made to evaluate the credibility of the placebo used; psychological factors may be largely responsible for differences between groups.
A widely used placebo method is sham-acupuncture or comparison of the effects of needling indicated and non-indicated acupoints. Every penetration of a needle through the skin, be it at an acupuncture point or not, produces physiological effects. These are partly due to activation of a pain-suppressing system in the spinal cord, diffuse noxious inhibitory controls (DNIC),6, 7 which can be activated by stimuli such as ice massage,8 heat,9 and vibration.10 Acupuncture has shown the same effect on the DNIC systems as thermal stimulation.11 Needling at trigger points other than acupoints has remarkable physiological effects.12, 13
With an effective placebo for acupuncture, patients should not be able to distinguish the placebo from the real penetration of a needle, and they should feel placebo penetration in the same therapeutic setting as in acupuncture. DEQI should be felt more often with acupuncture than with placebo. The same acupoints should be used with acupuncture and placebo and the skin should not be penetrated by a placebo treatment.
Section snippets
Placebo needle
We designed a placebo needle. The needle is not fixed inside the copper handle. Its tip is blunt, and when it touches the skin a pricking sensation is felt by the patient, simulating the puncturing of the skin. The needle moves inside the handle, and appears to be shortened. To place the needle we used a plastic ring covered with plastic sheet (figure 1); a procedure we also used in real acupuncture to ensure the same treatment setting. In acupuncture the tip of the needle is sharp and is
Results
Distribution of sex and mean age did not differ between the two groups of 30 volunteers (figure 2). The penetration of the needle was felt by 54 of the volunteers in the acupuncture group and in 47 of the placebo group. Penetration through the skin was felt in both acupuncture and placebo needling by 42 volunteers. Five felt the penetration using placebo needling, but did not feel penetration in the case of acupuncture. Twelve volunteers felt penetration of acupuncture but not with placebo. One
Discussion
Acupuncture seems to be a little more painful than placebo needling. The difference in VAS between acupuncture and placebo is small (4·15) with a large SD (11·57) and a large range (0–51) showing the individual range of pain perception. The differences in the VAS rating between the two needles is too small to reveal which was the placebo.
Seven volunteers felt no penetration with the placebo after having felt it first with acupuncture; none suspected that the skin had not been punctured, and
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