Objectives: In recent years the retractable type of sham needle has been anticipated to be a possible solution for masking patients in acupuncture research. However, this needle has been intended mainly for acupuncture-naïve subjects. The authors' goal in this study was to assess the validity of the retractable type of sham needle.
Methods: The authors conducted two randomized, single-blind, crossover trials with acupuncture-experienced subjects. Different acupuncture points were used in each trial (a LI-4 trial and a BL-23 trial). The subjects received two sessions of different stimulations in each trial. A Park Sham Needle was used in one session, a genuine acupuncture needle in the other.
Results: In the LI-4 trial, all of the 21 subjects (100%) felt penetration with the genuine needle, but only 7 of the 20 subjects (35%) felt a similar sensation with the sham needle (P=0.0002). Fifteen of the 21 subjects (71%) felt a dull sensation with the genuine needle, but only 4 of the 20 subjects (20%) felt a similar sensation with the sham needle (P=0.01). In the BL-23 trial, 14 of the 20 subjects (70%) felt penetration with the genuine needle and 10 of the 20 subjects (50%) felt "penetration" with the sham needle (P=0.39). Eight of the 20 subjects (40%) felt a dull sensation with the genuine needle and 2 of the 20 subjects (10%) did with the sham needle (P=0.109).
Conclusions: Potential factors that influence the applicability of "placebo" needling include not only inter-tester variability but also the patient's knowledge and experience of acupuncture, acupuncture point selection, the visual impact of needling, and so on.