Background
Acupuncture has been increasingly used as an alternative and complementary therapy in various clinical conditions, especially in the pain management [
1‐
3]. But its mechanism is still unclear. According to both ancient traditional Chinese and modern text books, the
deqi feeling of patients is different, which is referred as
suan (aching or soreness),
ma (numbness or tingling),
zhang (fullness/distention or pressure) or
zhong (heaviness) around the acupuncture point and/or along the meridians [
4,
5].
Recent controversy in the field of acupuncture research has been generated when several large scale RCTs showed no significant differences between acupuncture and minimal or sham acupuncture. But compared to control cases, the clinical effects of acupuncture treatment are significantly positive [
6‐
8]. It claims that
deqi is important in creating a positive clinical outcome [
5,
9]. Non-penetrative “placebo needles” such as the streitberger needle also elicited
deqi, which presenting a problem when acupuncture is evaluated within controlled trials [
10,
11]. Thus,
deqi may have implications both for clinical practice and trial design.
Deqi traits mean the nature of the sensation and intensity. There is no consensus for a method or instrument to quantify
deqi sensations. Particularly, few studies have investigated the effect of acupuncture on different aspects of
deqi or pain relief [
12,
13]. We had previously designed AAEPD-II to investigate immediate effects of acupuncture at a specific acupoint compared with unrelated acupoint and nonacupoint among primary dysmenorrhea patients. The present data was a secondary analysis from the main RCT to assess the effect of acupuncture on different aspects of
deqi and pain relief in primary dysmenorrhea.
Discussion
This secondary analysis of data aimed to assess acupuncture needling sensations and the therapeutic effect of acupuncture. The results showed that pain relief occurred after acupuncture treatment in primary dysmenorrhea patients. But there exist no significant differences among three groups in terms of intensity of deqi feeling.
Deqi is a central concept in traditional Chinese acupuncture [
2,
15]. Many investigators have attempted to assess the relationship between
deqi and therapeutic effects [
16,
17]. Some found better pain relief for acupuncture with
deqi[
18,
19], whereas others did not [
20,
21]. This result was similar to the results of White P
et al., who suggested that the presence and intensity of
deqi had no effect on pain relief for osteoarthritis (OA) patients [
17].
Deqi is comprised of the sensation of the patient and the sensation of the acupuncturist [
22]. Patients experienced
deqi as multiple unique sensations at the needle site and surrounding regions [
23]. Meanwhile, the perception of acupuncturist has been described as a slight pull of the needle downwards into the tissue [
4,
24,
25]. It was recommended that the study should have frequent recording of
deqi, using a much more sensitive measure and also be prudent to record any
deqi noted by acupuncturists.
Deqi is difficult to study because of its subjective nature and multifactor influence. Factors such as patient’s body constitution, severity of the illness, acupoint location, needling techniques, manipulation skills of the acupuncturist, competence and understanding of the TCM theory, also play an important role in the therapeutic outcome [
6].
Although this is not supported by current study that
deqi is stronger at acupoints than at nonacupoints [
26], sharp pain, heaviness and dull pain are the most frequent sensations in SP6 acupuncture group and GB39 control group. However, it was noted that numbness sensation occurred more often during acupuncture at nonacupoint, whereas the frequency of sharp pain and heaviness was similar to acupoints. Heaviness, aching, soreness, warmness and dull pain are conveyed by the slower-conducting Ad and C fibers, whereas numbness is conveyed by the faster-conducting Ab fibers [
27]. Acupuncture at SP6 tended to relieve the pain intensity easier in primary dysmenorrhea patients than those receiving acupuncture at GB39 or nonacupoint.
An appropriate method of measuring
deqi needs to be developed to support further acupuncture investigation. Researchers have sought to establish a credible rating scale for
deqi, such as the Subjective Acupuncture Sensation Scale (SASS) [
28,
29], the MASS [
13], the Southampton Needle Sensation Questionnaire [
16] and the “
deqi composite” [
30]. In past decades, functional magnetic resonance imaging (fMRI) had been used to qualitatively and quantitatively characterize
deqi sensations[
31]. An fMRI study found strong
deqi sensations induced strong deactivation of the limbic system [
32]. Hui
et al. found
deqi response of acupoint stimulation likely arises from A-delta and C-fiber stimulation by the needle [
30].
There are several limitations in this study. The decision of an appropriate control procedure for clinical studies on acupuncture is a particular challenge [
7]. Previous acupuncture RCTs suggested that needling of acupoints was as effective as nonacupoints, in particular for pain relief, although both interventions were more effective than a waiting list control [
21,
33,
34]. Few guidelines exist, however, for identifying appropriate sham point locations; the depth, direction, and duration of needle insertion; or the need for needle stimulation. Inserting a needle into any location is likely to have a physiological effect through a variety of mechanisms. It is still unknown what the sphere of influence is for local acupoints. For example, the distance of a point away from the needle-inserted acupoint that will not be also stimulated. Electrical stimulation was added after the initial
deqi sensations was elicited for dysmenorrhea pain relief. Electro-acupuncture tends to elicit a strong “tingling” sensation which can easily mask pure
deqi sensations. Besides, this is a secondary analysis of data from a RCT, which has a relatively big sample size and a statistical analysis in detail. However, in this paper, sample size is relatively small.
A power calculation was presented based on post hoc power analysis. This secondary data analysis was with a power of 25.44%. So this study may be underpowered to detect any differences. Possible reasons include that deqi is difficult to study because of its subjective nature and multifactor influence. Factors such as patient’s body constitution, severity of the illness, acupoint location, needling techniques, manipulation skills of the acupuncturist, competence and understanding of TCM theory, play important roles in the therapeutic outcome. Beside, patients experience deqi as multiple unique sensations at the needle site and surrounding regions. Multiple sensations usually present at the same time. It is underpowered to detect any differences for one single deqi sensations.
Due to the short term therapy and subjectivity of patients when rating the VAS scales, we found that the intensity of deqi during treatment does not relate to treatment outcome for primary dysmenorrhea pain. There are slight, but not clinical, differences in the most frequent sensations between acupoints and nonacupoints.
Competing interests
The authors declare that they have no competing interests.
Authors’ contributions
G-XS wrote and revised the manuscript, C-ZL and L-PW developed the original concepts for the review, Q-QLi, L-PG and M-MW have made substantial contributions to acquisition of data, analysis and interpretation of data; L-LH wrote the first draft of the paper. JW revised the manuscript. All authors contributed to the paper during development and read and approved the final version of the manuscript.