Systematic review of acupuncture placebo devices with a focus on the credibility of blinding of healthy participants and/or acupuncturists.

Background: An ideal placebo design in clinical research should resemble the intervention under investigation to facilitate blinding, yet remain clinically inert. With regard to physical interventions such as acupuncture, a true placebo device has not been developed and validated. Since 1998, researchers have designed several placebo acupuncture devices (PADs). The three most widely used PADs are the Streitberger, the Park and the Takakura device.

Aim: This review focuses on evaluating studies of these devices, in the context of credibility of blinding (COB), assessment of penetrating pain or sensation, and sensation.

Methods: Electronic database searches were conducted in four English and two Chinese databases from their inception until November 2016. All studies included in the review were conducted on healthy participants and compared verum manual acupuncture with any of the aforementioned PADs with respect to one or more of the above three outcomes related to blinding effect.

Results: The synthesised analyses of the 15 included studies showed that the Streitberger and Park placebo devices may not blind participants successfully when tested at a sensitive acupuncture point (LI4). In terms of penetrating sensation, there were significant differences between these two placebo devices and verum acupuncture when applied at this point. The Takakura device was the only PAD that had the potential to blind the acupuncturist. However, the blinding analyses of all outcome measures were inconsistent.

Conclusion: Overall, there were insufficient data to confirm the blinding effects of these skin-contact PADs as each device was associated with limitations that warrant further design improvements.