Discrimination accuracy between real and sham needles using the Park sham device in the upper and lower limbs

Abstract

Objective: To evaluate the blinding effectiveness of the Park sham acupuncture device using participants' ability to discriminate between the real and sham acupuncture needles in the (1) upper limb (TE points) compared with pure guessing and (2) lower limb (BL points) compared with pure guessing.

Methods: 20 healthy acupuncture-naïve university students and staff were recruited through convenience sampling. Participants made Yes-No judgements on whether the real or sham needle was administered to four TE acupoints on the dominant upper limb, and four acupoints along the BL meridian on the dominant lower limb. The proportion of correct judgements, P(C), for each participant was calculated to indicate the discrimination accuracy of participants in distinguishing between the real and sham needles. Separate P(C) were computed for the upper limb acupoints and lower limb acupoints. The data were also pooled to calculate a P(C) for a combination of both body regions.

Results: The participants' discrimination accuracy between the real and sham needles was not statistically significant from P(C)=0.5 (chance level) for the lower limb alone and combined body regions' acupoint comparisons (lower limb: t(19)=0.00, unadjusted p=1.00; combined: t(19)=1.75, unadjusted p=0.10). However, the participants' discrimination accuracy was statistically significant from P(C)=0.5 for the upper limb acupoints alone comparison (t(19)=2.36, unadjusted p=0.03).

Conclusions: This study showed that the Park sham device is more likely to blind participants in differentiating between the real and sham needles in the lower limb (BL meridian) acupoints than in the upper limb (TE meridian). However, the participants' ability to differentiate between the needle types for the upper limb acupoints was significantly different from chance levels.