Placebo effect of acupuncture in clinical study

Placebo control is designed to evaluate the specific effect of one intervention. Relevant studies showed that acupuncture has a considerable placebo effect affected by many factors. In this paper, the relevant articles of acupuncture placebo studies all around the world were reviewed comprehensively to clarify the definition of acupuncture placebo effect and its psychological mechanism. The factors of acupuncture placebo effect were discussed in view of three aspects, i.e. types of sham acupuncture as control, patient-doctor interaction and outcome types. Eventually, the issues encountered in current studies of acupuncture placebo effect were described, e.g. lack of relevant studies especially with systematic and in-depth approaches in this field, inappropriate classification of specific non-needling effect relevant with acupuncture theory, and inaccurate assessment of acupuncture placebo effect due to the difficulty of sham-acupuncture design. In order to drive the future research direction of acupuncture placebo effect, it is suggested that more attention should be paid on the topic, including but not limited to correct recognition of the holistic effect of acupuncture, the appropriate design of sham acupuncture and in-depth research of mechanism of acupuncture placebo effect and its contributing factors.