Tapping-in method (skin penetration technique) with a placebo needle for double-blind acupuncture trials

This study investigated the effect of acupuncture needles developed for double-blind (practitioner-patient blinding) trials employing a tapping-in method that is commonly used to penetrate the skin in Japanese-style acupuncture. DESIGN, SUBJECTS, AND INTERVENTIONS: An acupuncturist applied a penetrating, a skin-touch placebo, and a no-touch control needle designed to blind both practitioners and patients in the forearm in 80 healthy subjects (patients) by tapping-in method.

The setting was a practice room of the Japan School of Acupuncture, Moxibustion and Physiotherapy, Tokyo, Japan.

The outcome measures were the acupuncturist's and subjects' guesses at the type of needles and confidence of their guesses on a 100-mm visual analogue scale (VAS). The subjects were asked about pain with needle application.

The number of correct/incorrect guesses (the latter including unidentified) of the acupuncturist were 73/167 with a confidence of 55.2 ± 16.9 (mean ± standard deviation) on the VAS. The subjects identified 148 needles correctly and 92 needles incorrectly, the mean confidence being 71.0 ± 28.4. There were a few penetrating and skin-touch placebo needles that the subjects guessed as "no-touch." Whereas few of the 80 no-touch control needles were guessed as "penetrating," 16% of them were guessed as "skin-touch" and 11% were reported as "unidentifiable" by the subjects. Forty percent (40%) of the penetrating needles and 50% of the skin-touch placebo needles did not elicit skin penetration pain.

The effect of practitioner blinding employing the needles for double blinding with the tapping-in method was satisfactory. It was difficult to blind the subjects when no-touch control needles together with penetrating and skin-touch placebo needles were used.