Acupunct Med 29:208-214 doi:10.1136/aim.2010.003210
  • Original papers

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

  1. Derek Santos
  1. School of Health Sciences, Queen Margaret University Edinburgh, Edinburgh, UK
  1. Correspondence to Chee-Wee Tan, Queen Margaret University Edinburgh, Queen Margaret University Drive, Edinburgh EH21 6UU, UK; ctan{at}
  • Accepted 26 April 2011
  • Published Online First 7 June 2011


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: t19=0.00, unadjusted p=1.00; combined: t19=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 (t19=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.


  • Competing interests None.

  • Ethics approval This study was conducted with the approval of the Queen Margaret University Research Ethics Committee.

  • Provenance and peer review Not commissioned; externally peer reviewed.