Do we really understand what constitutes an acupuncture point?

Acupuncture is increasingly being used for the management of various pain conditions. A large number of clinical studies and systematic reviews on this topic have been published. However, methodological shortcomings have plagued much of the earlier acupuncture research. During the last decade, the quality of randomized trials of acupuncture has improved. Recent well-designed studies have shown that acupuncture was more effective than usual care in a variety of painful conditions. However, many of those studies found no differences between ‘verum acupuncture’ and ‘sham acupuncture’ (Moffet, 2009). Compared to no treatment, the latter was also associated with larger effect sizes compared to conventional placebo. Achieving adequate blinding is one of the biggest challenges of acupuncture research. The aim of sham acupuncture is to produce blinding of subjects by making them unable to distinguish between ‘real’ and ‘mock’ acupuncture, while missing all relevant needling and non-needling components of acupuncture that are believed to contribute to the desired effect. Sham acupuncture has been achieved by needling a presumed non-acupuncture point or an acupoint thought to be clinically irrelevant, not penetrating the skin, placing the needle superficially or altering needle stimulation parameters compared to verum acupuncture. According to traditional Chinese theory, acupoints are distributed along ‘meridians’ or ‘channels’, and the ability to locate an acupoint accurately is essential for effective treatment. So how accurately are we able to locate acupoints? Is the precise needle location really important in achieving the desired clinical benefit from acupuncture? And how should sham points be chosen in clinical trials of acupuncture? In this issue of the European Journal of Pain, Molsberger and colleagues (Molsbeger et al., 2012) examined the precision of localization of 23 acupoints by 71 physicians who were experienced, adequately trained and actively involved in acupuncture. They report significant variability in point localization with a mean area for the 95% confidence intervals of all point localizations of 19.4 cm (range 2.6–41.4 cm). The authors suggest that such variability in acupoint localization likely occurs in the setting of acupuncture trials, and that the efficacy of acupuncture in those trials implies that accurate textbook localization of those points is not critical and supports the concept of larger acupuncture fields rather than small acupuncture points. They also suggest that such poor localization might explain the lack of difference between verum and sham acupuncture in trials where sham is placed in close proximity to verum points. It is interesting that for even commonly used acupoints located on small areas of the body such as the PC6, there was still significant variability in point localization. However, acupoints might not lie exactly on their map location and many acupuncturists rely on eliciting the deqi sensation and therefore would produce adjustments to their point localization and the angle of needle insertion to achieve this. It is also possible that acupuncturists involved in a clinical trial might receive focused training on the acupoints involved in that trial, and therefore, there could be less variability in localization. Previous studies have also reported significant variability in point localization by practitioners and imprecision of commonly used acupoint location methods (Aird et al., 2002). Acupoints are located by reference to immediately adjacent structures or by measurement from a landmark. It has also been suggested that acupuncture points have bioelectrical properties. However, these theories are supported by little systematic research (Ahn et al., 2008).