English

Abstract

Introduction There is increasing evidence that acupuncture is an effective therapeutic technique for some patients with painful conditions; but, there is ongoing controversy as to whether this effect is primarily due to mechanical or direct effects of acupuncture (verum) or non-specific factors, including placebo (sham). This paper explores some of the issues involved in differentiating these, including the difficulty in designing a true sham acupuncture technique for investigative purposes; the range of techniques employed in acupuncture; how points to be treated are selected; and the role of placebo in acupuncture delivery. Conclusion It is likely that placebo effects contribute to, or enhance, the therapeutic effects of acupuncture; but, the exact mechanism by which verum acupuncture works has yet to be fully elucidated. Introduction While acupuncture has been employed as a therapeutic technique for thousands of years, the development of an evidence base to support its use is still a work in progress. Since acupuncture first came to the attention in the West in the early 1970s1, there have been numerous published studies on its therapeutic benefit, or lack thereof, with the majority directed towards its role in management of pain2. Although the results of a recent large systematic review have suggested that there is a definite therapeutic benefit from acupuncture for pain3, the debate is still ongoing about the how acupuncture exerts this effect, with the exact mechanism yet to be defined4. Much of this debate relates to whether acupuncture’s effect is due to the precise selection of points to be treated (often termed verum acupuncture), or, alternatively, whether the effects are non-specific and have limited, if any, relationship with precise selection of points (placebo, or sham acupuncture)5. Proponents of verum acupuncture generally attribute its effect to one or more of stimulation of superficial Ab fibres, resulting in the inhibition of painful stimuli from the periphery; activation of descending pain control systems in the mid-brain; and release of b-endorphin and met-enkephalin in the brain and spinal cord6. Yet, none of these appear to be specific for acupuncture point selection based upon Traditional Chinese Medicine approaches2. More recent work has suggested alternative mechanisms, including modulation of the subcutaneous fascial network7, and neural blockade8; but as yet, there is no uniformly accepted mechanism. In contrast, the proponents of sham acupuncture attribute its effects to nonspecific factors, including underlying psychological factors, expectation and a general “placebo” effect4. To attempt to answer the question whether acupuncture is a non-specific placebo or a specific therapeutic intervention, the reader will need to understand the difficulty in designing a true sham acupuncture technique for investigative purposes, the range of techniques employed in acupuncture, how points to be treated are selected and the role of placebo in acupuncture delivery. Discussion The author has referenced some of his own studies in this review. These referenced studies have been conducted in accordance with the Declaration of Helsinki (1964), and the protocols of these studies have been approved by the relevant ethics committees related to the institution in which they were performed. All human subjects, in these referenced studies, gave informed consent to participate in these studies. Challenges in sham acupuncture delivery Although, to this point, the terms verum and sham have been used in an exclusive manner, the practical distinction between these two termswhen applied to acupunctureis not clearly defined. Clinical trials comparing verum and sham acupuncture frequently employ very similar techniques, including the use of needles4. Although earlier trials have compared the points described during acupuncture performed at Traditional Chinese Medicine (as verum) with acupuncture at other skin sites (as sham)9–12, recent research suggests that acupuncture point localisation is not uniform between practitioners13, and that this lack of precision may contribute to the variability in trial outcomes14. Some trials have utilised modified needles15, or needling with minimal pressure16,17 as sham, but the lack of a generally-accepted mechanism as to how acupuncture works has resulted in uncertainty in interpreting the results of these trials4. Acupuncture modalities In addition to the widely known practice of inserting fine needles into designated skin points (the technique by * Corresponding author Email: m.silberstein@curtin.edu.au Faculty of Science and Engineering, Curtin University, Perth, WA, Australia