The efficacy of traditional acupuncture on patients with chronic neck pain: study protocol of a randomized controlled trial

Chronic neck pain (CNP) is a serious public health and socioeconomic problem worldwide. Studies have shown that the overall prevalence of CNP varies from 0.4 to 86.8% (mean 23.1%) [1]. The prevalence of CNP is greater among office workers than manual workers. This condition is characterized by activity limitations, dizziness, anxiety and insomnia [2]. Physical exercise, massage or physiotherapy, as well as education, have been proved to be efficient in reducing neck pain [3‐6]. Acupuncture has also been well accepted as a non-pharmacological treatment for neck pain [7]. However, the treatment effect of acupuncture is moderate [8]. One argument is that “acupuncture is not associated with clinical effects beyond a powerful placebo response” [9, 10].

A growing body of research indicates that clinical trials of acupuncture have encountered many methodological challenges, including the identification of appropriate treatment and control groups, deficiencies in the blinding and follow-up of chronic pain [11]. Firstly, variable acupoints at different sites are commonly selected for the same disease in clinical practice. Based on our clinical experience, more than 20 acupoints have been selected as the main acupoints in neck pain. An appropriate repeatable treatment has not been established. Secondly, although shallow needle insertion and non-acupoints have been widely used in acupuncture research in sham groups, it has been suggested that these methods have therapeutic effects and are adjusted to accommodate different patients according to traditional Chinese medicine (TCM) theory [12]. The academic literature also indicates that the human body has more than 2200 singular points within formal naming beyond meridians [12]. The notion of a non-acupoint is obscure and there may be a role for specific factors of non-acupoints lateral to the acupoints [13]. Moreover, recent academic literature has shown that shallow puncture also produces analgesic effects in pain disorders. Thirdly, it has been reported that about 40% of subjects in these trials could distinguish non-penetrating sham acupuncture from real acupuncture [14].

In view of these doubts, the influence of different needling points and depths should be investigated. First, the acupoints of local lesions including Jingbailao (EX-HN 15) and Jianzhongshu (SI 15) are commonly used in our hospital for neck pain [15]. The analgesic mechanism of acupoints on local lesions has been established in the spinal segments control theory to explain the gate control theory [16, 17]. According to the innervations of the pain focus, the effects of stimulation of EX-HN 15 and SI 15 on neck analgesia will be studied for feasibility and repeatability [15]. Second, several different groups of non-acupoints and shallow punctures will be established to determine whether traditional acupuncture is more effective for chronic pain relief than sham acupuncture in adults with CNP. The different depth and placement of needle insertion will also be investigated to determine efficacy [18]. Third, a single-blinded practice will be used and the adequacy of subject blinding will also be carefully assessed. The patients will be advised to lie in the prone position on the treatment couch and will be unaware of the treatment course in this trial. Data collection will be completed by the researchers over a 3-month follow-up period. Finally, we will assess the pain threshold (PT) and pain diary as semi-objective outcomes to avoid subjective results.

In this research, a randomized clinical trial will be performed to determine whether the outcome of traditional acupuncture treatment is significantly different to sham acupuncture in relieving CNP. We also aim to investigate which type of sham acupuncture is the optimal control for clinical trials.

Acupuncture has been practiced for more than two millennia in China. In the practice of traditional acupuncture analgesia, it is generally acknowledged that structures and physiological functions are modulated by 14 energy meridians and the hypothetical “Qi” is usually translated as energy [30]. Acupuncturists with different experiences might have the different methods to operate de-qi (bring about the desired sensation) for the acupuncture intervention. Findings from clinical research strongly suggested that these specific differences of interventions have a major impact on the response to the curative effect [31]. Therefore, further trials are required to investigate the differences in these methods.

According to TCM theory, acupoints can be selected in three ways: an acupoint can be selected at a local lesion (with the pain area as acupoint Shu), far away from the local lesions, such as on limbs, and in accordance with symptoms. For non-acupoints at local lesions, the possible mechanisms of the analgesic effect may include the gate control theory triggered by neural pathways, alterations in local circulation and the immune environment [32]. Moreover, for shallow needle insertion, some researchers believe that shallow puncture can stimulate afferent nerves and activate the corresponding brain regions to produce a “limbic touch response” [33, 34]. Previous studies have also suggested that non-acupoints beyond the meridian and shallow puncture have an analgesic effect in subjects with fibromyalgia and other chronic pain conditions [35, 36]. Although the use of the “Streitberger” needle with a blunt tip has been supported in studies and reviews, it was reported that nearly half of the subjects could distinguish it from the real treatment in pain disorders [14, 37]. Therefore, further trials are required to investigate these differences. It is necessary to establish a standard for the control (sham) in clinical research due to the unknown analgesia mechanisms of traditional acupuncture.

Clinical trials of traditional acupuncture for chronic pain, with optimal control groups, are rare, with the exception of the use of standard outcome measures and rigorous blinding of participants to treatment assignment [38]. However, few guidelines exist for conducting appropriate sham acupuncture, for the depth of the inserted needle or the parameter for needle stimulus [39, 40]. This randomized placebo-controlled trial addresses the urgent need to provide evidence-based control groups for adults with CNP and to determine the evidence for the specificity of acupoints. At the end of this clinical trial, we expect that the findings will provide evidence to answer the question: is acupuncture more effective than a placebo?