Placebo acupuncture in an acupuncture clinical trial. How good is the blinding effect?

The purpose of this study was to critically look at the validity of the "placebo procedures" used in acupuncture studies. Twenty healthy volunteers were recruited and blinded either to genuine acupuncture or to "placebo procedures", and they were checked to ascertain whether they could differentiate genuine punctures from placebo punctures. Each volunteer received paired procedures on three separate occasions. Each paired procedure included one genuine puncture and a placebo procedure. Three placebo procedures, that is, sham points, superficial puncture, and puncturing through a special device, were used. Two standard acupuncture points were used: Hegu (LI-4) in the hand and Zusanli (ST-36) in the leg. Among the 18 participants who completed all three tests, 16 correctly recognized genuine punctures. Sham sites in the hand and the leg were detected by 15 and nine of the participants, respectively. Superficial punctures in the hand and the leg were recognized by 10 and nine of the participants, respectively. A special device, a foam cylinder that hid the distal needle, worked best because 15 and 16 of the participants were deceived when the device was used at an acupoint in the hand and the leg, respectively. No significant differences were noted between those who had had past experience with acupuncture and those who had not. Sham sites and superficial punctures appeared not to have a placebo function because 50-83% of the participants were able to immediately recognize their false nature. Using a hidden device worked much better.