Research Article
Split ViewerEvaluation of Newly Developed Sham Acupuncture Needle with a Special Focus on Needling Sensation: a Randomized Controlled Trial
1Department of Acupuncture and Moxibustion, Graduate School of Health Sciences, Teikyo Heisei University, Tokyo, Japan
2Department of Acupuncture and Moxibustion, Faculty of Health Care, Teikyo Heisei University, Tokyo, Japan
3Research Institute of Oriental Medicine, Teikyo Heisei University, Tokyo, Japan
This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
J Acupunct Meridian Stud 2023; 16(1): 30-39
Published February 28, 2023 https://doi.org/10.51507/j.jams.2023.16.1.30
Copyright © Medical Association of Pharmacopuncture Institute.
Abstract
Objectives: To ascertain how differently participants feel sham and real needles and to evaluate whether sham needles are effective in clinical trials.
Methods: After enrolling 64 healthy volunteers who had experienced and were knowledgeable about acupuncture, the practitioner randomly used real and sham needles at four sites (bilateral LI4 and LI10) on the participants’ forearms. A custom-made sham blunt stainless acupuncture needle (40 mm, 0.80 mm) that was inserted into a guide tube was used. Immediately after needling, the participants were questioned in regard to their identification of the needle, skin penetration sensation, and de qi.
Results: The sham needle resulted in 62.5% blinding. Inequivalent sensations were elicited by the sham needles compared to the real needles. Women reported similar needling sensations from the sham and real needles.
Conclusion: This study achieved comparatively higher sham-needle blinding and is therefore worthy of use in clinical trials. The mutual independence of the sham needle from the real needle was mediated presumably by interindividual differences among the participants and the needling sites. Sex differences in sensation were likely related to the blinding capability of the sham needle.
Keywords
INTRODUCTION
In randomized controlled trials of acupuncture stimulation and treatment, sham or placebo acupuncture needles are used in the control group [1,2]. Non-penetrating sham and placebo acupuncture needles have been developed by Streitberger and Kleinhenz [3], Park et al. [4], and Takakura and Yajima [5], and the sham needles are designed to be visually and somatosensorily mimic real needles, which inherently blinds the participants to the experimental condition. Accordingly, trials have been conducted to consider the reliability and validity of the sham needles [6-10]. Although useful, these sham and placebo acupuncture needles have a pedestal (flange) for holding the guide tube that induces tactile stimulation of the skin and makes these needles look different from the usual acupuncture treatment needles, which makes it difficult to compare true acupuncture stimulation. The existing sham acupuncture needles are difficult to manufacture and have little versatility. Thus, there is a need for simple and efficient sham acupuncture needles that are designed with a special focus on the needling sensation [11].
This study was conducted to primarily ascertain how differently participants feel sham and real needles to evaluate whether a simple original sham acupuncture needle that has been designed with a special focus on the needling sensation would be effective in clinical trials. In addition, the secondary objective was to compare the needling sensations and examined how the sex, site of insertion, and trial number affected the blinding of sham acupuncture needle.
MATERIALS AND METHODS
1. Trial design
The trial design was a randomized controlled trial that was conducted from October to December 2021.
2. Participants
The participants of this study were 64 healthy volunteers (32 males and 32 females; age: 21.7 ± 1.4 years [mean ± standard deviation]) with former knowledge of and experience with acupuncture who were enrolled from the Department of Acupuncture and Moxibustion at Teikyo Heisei University. Data were collected at Teikyo Heisei University.
This study was approved by the ethics committee of Teikyo Heisei University, Tokyo, Japan (approval number: 2021-024) and was registered in the University Hospital Medical Information Network Clinical Trials Registry (UMIN: 000045923). All participants were provided a written and an oral explanation about the study and the study-related procedures, and written informed consent was obtained. All experiments were conducted in accordance with the principles of the Declaration of Helsinki and have been reported in accordance with the CONSORT and STRICTA guidelines.
3. Sham acupuncture needle
We used custom-made (in-house) sham acupuncture needles made of disinfected stainless acupuncture needles (0.80 mm diameter and 40 mm length; TAIHO Medical Products Co., Ltd.) that were inserted into a custom-made guide tube (Fig. 1). The tip of the sham acupuncture needle was blunted to prevent skin puncture. To match the diameter of the sham acupuncture needle, the guide tube had an inner diameter of 0.80 mm and measured 50-60 mm in length. The sham acupuncture needle was used with a needling technique that involved stabilization of the needle at the needling site (similar to the insertion of a real acupuncture needle; Fig. 2A), followed by subsequent light tapping of the needle head (Fig. 2B), then pulling it out (Fig. 2C), and eliciting stimulation through the tip of the guide tube (Fig. 2D).
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Figure 1.Design of the sham and real acupuncture needles. The left side shows the custom-made sham acupuncture needle (0.80 mm diameter, 40 mm length), the custom-made guide tube (50-60 mm length), and the tip of the sham acupuncture needle. The right side shows the real acupuncture needle (0.20 mm diameter, 40 mm length), the guide tube, and the tip of the real acupuncture needle. The tip of the sham acupuncture needle is blunt so as not to penetrate the skin. The guide tube is made to have an inner diameter of about 0.80 mm to match the diameter of the sham acupuncture needle.
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Figure 2.The needling technique for the sham acupuncture needle. The needling technique for the sham acupuncture needle is shown in A, B, C, and D. Prepare to perform the sham acupuncture needle demonstration by stabilizing the sham acupuncture needle at the needling site, similar to before the insertion of a real acupuncture needle (A). Subsequently lightly tap the head of a needle (B), pull out a needle (C), stimulation by just thin guide tube’s tip (D).
4. Outcome assessments
The primary outcome measure was needle identification whereas the secondary outcome measures were the presence or absence of a skin-penetration sensation and
5. Protocol
The practitioner randomly performed acupuncture with real and sham needles at four sites (bilateral LI4 and LI10) on the forearms of each participant under four set conditions: [A]: LI4 (right) → LI4 (left) → LI10 (right) → LI10 (left); [B]: LI4 (left) → LI4 (right) → LI10 (left) → LI10 (right); [C]: LI10 (right) → LI10 (left) → LI4 (Right) → LI4 (left); and [D]: LI10 (left) → LI10 (right) → LI4 (left) → LI4 (right). Additionally, there were 16 categories for the selection of real and sham needles for each of the four sites. Therefore, the participants were assigned randomly and unbiasedly to 64 categories (4 categories × 16 categories) in this study by using a random number table, with sex as the allocation factor, by individuals who were uninvolved in the conduct of the experiments.
The mean room temperature and humidity were 25.6 ± 1.9℃ and 57.3% ± 9.5%, respectively. Prior to the experiment, the participants were informed that either real or sham acupuncture would be used. The participants wore an eye mask while in a seated position and placed their forearms on the table. The practitioner randomly performed real and sham needle-based acupuncture at four sites of the bilateral LI4 and LI10 for each participant: LI4 was located on the radial aspect, to the midpoint of the second metacarpal bone, and LI10 was located on the posterolateral aspect of the forearm, 60 mm inferior to the cubital crease. A sterile stainless acupuncture needle (diameter, 0.20 mm; length, 40 mm; SEIRIN Co., Shizuoka, Japan) was used for the real acupuncture and was inserted perpendicularly, via a simple insertion technique, to a depth of 15 mm under the skin and then withdrawn immediately. Immediately after performing acupuncture with each needle, the evaluator interviewed the participants about the needle identification and the presence or absence of a skin-penetration sensation and
6. Statistical analysis
JMP® Pro 15.0.0 (SAS Institute Japan Ltd.) was used for all the statistical analysis. Results of the primary and secondary outcome measures are shown in the contingency table. Pearson’s chi-square test was used to ascertain the associations between the two groups.
RESULTS
1. Full data
We analyzed data from 64 participants (256 times, in total) who met the eligibility criteria because there were no losses and exclusions after randomization in each group. The basic attributes at baseline for each group are shown in Table 1. Adverse events resulting from the real acupuncture intervention included bleeding in 5 cases whereas no adverse events were observed with the sham acupuncture intervention.
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Table 1 . Baseline demographic and clinical characteristics for each group
Group Real needle Sham needle LI4-right
(n = 32)LI4-left
(n = 32)LI10-right
(n = 32)LI10-left
(n = 32)LI4-right
(n = 32)LI4-left
(n = 32)LI10-right
(n = 32)LI10-left
(n = 32)Male/Female 18/14 17/15 16/16 15/17 14/18 15/17 16/16 17/15 Age (mean ± SD) 21.8 ± 1.5 21.8 ± 1.4 21.7 ± 1.4 21.8 ± 1.2 21.7 ± 1.4 21.7 ± 1.5 21.7 ± 1.4 21.7 ± 1.6
Needles were tested at four sites (bilateral LI4 and LI10) on 64 participants. Therefore, data from a total of 256 sessions are shown in Table 2A. For the sham needles, “Felt real” was reported 18 times (14.1%), “Maybe felt real” was reported 52 times (40.6%), “Didn’t know” was reported 10 times (7.8%), “Maybe felt fake” was reported 32 times (25.0%), and “Felt fake” was reported 16 times (12.5%) (Table 2A). Moreover, the correct and incorrect answers for sham needles were determined as 48 and 80 times, respectively (incorrect answer rate: 62.5%; Table 2B). In contrast, correct and incorrect answers for real needles were obtained 99 and 29 times, respectively (correct answer rate of 77.3%; Table 2B). According to these results, the sham needle showed 62.5% blinding potential, which was close to the rate of correct answers for the real needle.
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Table 2 . The results of the identification and sensation by subjects
(A). The result about the identification of real and sham needles by subjects
Felt a real Maybe felt a real Didn’t know Maybe felt a fake Felt a fake Total Real needle 63 (49.2%) 36 (28.1%) 5 (3.9%) 20 (15.6%) 4 (3.1%) 128 Sham needle 18 (14.1%) 52 (40.6%) 10 (7.8%) 32 (25.0%) 16 (12.5%) 128 Total 81 88 15 52 20 256 (B). Correctly answered rate of real needle and incorrectly answered rate of sham needle
Correct Incorrect Correctly answered (rate) Real needle 99 (Felt a real + Maybe) 29 (Felt a fake + Maybe+ Didn’t know) 99/128 (77.3%) Correct Incorrect Incorrectly answered (rate) Sham needle 48 (Felt a fake + Maybe) 80 (Felt a real + Maybe + Didn’t know) 80/128 (62.5%) (C). Comparison of the identification of needle, skin penetration sensation and
de qi Correct or incorrect Felt a real Felt a fake Total Real needle 99 24 123 Sham needle 70 48 118 Total 169 72 241 Pearson χ2 test: χ2 = 12.878, df = 1, p < 0.001Skin penetration sensation Felt Didn’t feel Total Real needle 101 (78.9%) 27 (21.1%) 128 Sham needle 80 (62.5%) 48 (37.5%) 128 Total 181 75 256 Pearson χ2 test: χ2 = 8.316, df = 1, p = 0.0039De qi Felt Didn’t feel Total Real needle 45 (35.2%) 83 (64.8%) 128 Sham needle 17 (13.3%) 111 (86.7%) 128 Total 62 194 256 Pearson χ2 test: χ2 = 16.686, df = 1, p < 0.001(D). Comparison of gender when sham needles were performed
Correct or incorrect Felt a real Felt a fake Total Male 28 29 57 Female 42 19 61 Total 70 48 118 Pearson χ2 test: χ2 = 4.753, df = 1, p = 0.029Skin penetration sensation Felt Didn’t feel Total Male 31 (50.0%) 31 (50.0%) 62 Female 49 (74.2%) 17 (25.8%) 66 Total 80 48 128 Pearson χ2 test: χ2 = 8.016, df = 1, p = 0.0046De qi Felt Didn’t feel Total Male 6 (9.7%) 56 (90.3%) 62 Female 11 (16.7%) 55 (83.3%) 66 Total 17 111 128 Pearson χ2 test: χ2 = 1.356, df = 1, p = 0.24(E). Comparison of the identification of needle, skin penetration sensation and
de qi in maleCorrect or incorrect Felt a real Felt a fake Total Real needle 49 14 63 Sham needle 28 29 57 Total 77 43 120 Pearson χ2 test: χ2 = 10.687, df = 1, p = 0.0011Skin penetration sensation Felt Didn’t feel Total Real needle 49 (74.2%) 17 (25.8%) 66 Sham needle 31 (50.0%) 31 (50.0%) 62 Total 80 48 128 Pearson χ2 test: χ2 = 8.016, df = 1, p = 0.0046De qi Felt Didn’t feel Total Real needle 22 (33.3%) 44 (66.7%) 66 Sham needle 6 (9.7%) 56 (90.3%) 62 Total 28 100 128 Pearson χ2 test: χ2 = 10.468, df = 1, p = 0.0012(F). Comparison of the identification of needle, skin penetration sensation and
de qi in femaleCorrect or incorrect Felt a real Felt a fake Total Real needle 50 10 60 Sham needle 42 19 61 Total 92 29 121 Pearson χ2 test: χ2 = 3.481, df = 1, p = 0.062Skin penetration sensation Felt Didn’t feel Total Real needle 52 (83.9%) 10 (16.1%) 62 Sham needle 49 (74.2%) 17 (25.8%) 66 Total 101 27 128 Pearson χ2 test: χ2 = 1.781, df = 1, p = 0.18De qi Felt Didn’t feel Total Real needle 23 (37.1%) 39 (62.9%) 62 Sham needle 11 (16.7%) 55 (83.3%) 66 Total 34 94 128 Pearson χ2 test: χ2 = 6.840, df = 1, p = 0.0089(G). Comparison of LI4 and LI10 when sham needles were performed
Correct or incorrect Felt a real Felt a fake Total LI4 40 21 61 LI10 30 27 57 Total 70 48 118 Pearson χ2 test: χ2 = 2.045, df = 1, p = 0.15Skin penetration sensation Felt Didn’t feel Total LI4 45 (70.3%) 19 (29.7%) 64 LI10 35 (54.7%) 29 (45.3%) 64 Total 80 48 128 Pearson χ2 test: χ2 = 3.333, df = 1, p = 0.068De qi Felt Didn’t feel Total LI4 9 (14.1%) 55 (85.9%) 64 LI10 8 (12.5%) 56 (87.5%) 64 Total 17 111 128 Pearson χ2 test: χ2 = 0.068, df = 1, p = 0.79(H). Comparison of the trial nums when sham needles were performed
Correct or incorrect Felt a real Felt a fake Total 1st 18 13 31 2nd 18 11 29 3rd 14 16 30 4th 20 8 28 Total 70 48 118 Pearson χ2 test: χ2 = 3.803, df = 3, p = 0.28Skin penetration sensation Felt Didn’t feel Total 1st 20 (62.5%) 12 (37.5%) 32 2nd 21 (65.6%) 11 (34.4%) 32 3rd 18 (56.3%) 14 (43.7%) 32 4th 21 (65.6%) 11 (34.4%) 32 Total 80 48 128 Pearson χ2 test: χ2 = 0.800, df = 3, p = 0.84De qi Felt Didn’t feel Total 1st 4 (12.5%) 28 (87.5%) 32 2nd 3 (9.4%) 29 (90.6%) 32 3rd 6 (18.8%) 26 (81.2%) 32 4th 4 (12.5%) 28 (87.5%) 32 Total 17 111 128 Pearson χ2 test: χ2 = 1.3289, df = 3, p = 0.73df = degrees of freedom.
2. Differences in identification and sensations between sham and real needles
To evaluate the difference in the stimulation sensation between the sham and real needles, we compared the reported needle identification, skin-penetration sensation, and
3. Sex difference in the sham needle outcomes
To evaluate sex differences in the needling sensation elicited by a sham needle, we compared the sham needle identification, skin-penetration sensation, and
As such, we analyzed the differences in needling sensation between real and sham needles separately for men and women (Tables 2E and 2F). For men, real and sham needles were non-independent across all outcomes (identification, skin-penetration sensation, and
4. Differences in the sham effect between forearm sites, LI4 and LI10
To evaluate the differences in sham needle-needling sensation on the forearms, we compared the rate of needle identification, skin-penetration sensation, and
Additionally, the number of incorrect answers and the incorrect answer rate for sham needles in the LI4 were 43 times and 67.2%, respectively, and the number of incorrect answers and the incorrect answer rate for sham needles in the LI10 were 37 times and 57.8%, respectively.
5. Differences in the influence of trial number on sham needle-elicited sensations
To evaluate the differences in sham-needle needling sensation as a function of trial number, we compared needle identification, skin penetration sensation, and
DISCUSSION
This study evaluated the sensation that sham acupuncture needles elicit at the LI4 and LI10 sites of the forearm in healthy volunteers with knowledge of and experience with acupuncture. The results showed that the sham needle conferred 62.5% blinding potential and induced a skin-penetration sensation in 62.5% of the participants. However, the sensations elicited by sham and real needles were not equivalent. In contrast, in women, the needling sensation from the sham needle was equivalent to that of a real needle. Therefore, it was shown that blinding capacity of the sham needle was influenced by sex.
The overall data and the separate LI4 and LI10 sham needle results show a blinding rate of 62.5% (80/128), 67.2% (43/64), and 57.8% (37/64), respectively. Previous studies that compared and evaluated the validity of sham and placebo acupuncture needles have been conducted under various conditions, using various indices [11,12]. Similar to this study, the blinding rate of sham needles for LI4 was reported by White et al. as 50.0% (10/20) [13], by Chae et al. as 14.3% (2/14) [14], and by Lee et al. as 55.0% (22/40) [15]. Moreover, a study conducted on healthy volunteers with knowledge and experience with acupuncture showed 56.1% (64/114) blinding at different needling sites [8]. Therefore, compared to existing sham needles that are used in clinical trials, the sham needle used in this study showed a higher blinding capacity and is worth being applied to clinical trials.
Factors that influence the blinding of sham acupuncture needles include the participant’s mental and physical state, race, acupuncture experience and knowledge, acupuncture point selection (upper/lower extremities or back), and the appearance of the needles (visual impact) [12,13,16]. When using the sham needle, blinding may not be as efficient in healthy participants compared to that in patients. Moreover, blinding may not be as efficient in participants with experience and knowledge of acupuncture, and in placement into the LI4 of the forearm [12]. In this study, all evaluations under stringent conditions were conducted to use sham needles and were focused on needling sensation. However, the needling sensation by sham and real needles was not equivalent. The results of this study are targeting both the LI4 and LI10 sites of the forearms in healthy volunteers with knowledge of and experience with acupuncture. In a previous study, it has been reported that even participants with experience and knowledge of acupuncture can be blinded by needling in less sensitive sites. Therefore, it is thought that the sham needle is possible to induce a needling sensation equivalent to real needle depending on the needling sites (i.e., the lower limbs and the lumbar regions).
Furthermore, the recognition of a skin-penetration sensation was observed to be strongly involved in the identification of acupuncture stimulation. Takakura and Yajima [8] report that skin penetration/penetration-like pain would be the main factor that influences identification of acupuncture needle. Therefore, in this study, it is also considered that, compared to the
One important finding of this study was that in females, the sham-needle needling sensation was equivalent to that induced by the real needle. Sex differences have not been previously reported and could not be compared to previous studies. Differences in pain thresholds between males and female were considered as a potential factor explaining the gender difference in blinding of the sham needle. Indeed, Lue et al. [17] reported higher thermal pain thresholds in males compared to females. Furthermore, the stimulation of the skin by the tip of the sham needle may cause excitation of not only group II fibers but also group III and IV fibers, depending on the structure and degree of stimulation, thereby inducing a real needle-like skin penetration sensation. Therefore, it is suggested that the blinding of sham needles was higher in females with a low thermal threshold, giving a sensation equivalent to that of real needles.
The effect of trial number using sham needles was evaluated and not found to be involved in the blinding capacity of the sham needle. There are reports that sham needle research is not suitable for crossover designs, and that the involvement of trial numbers is unclear [10,18]. However, given the lack of an effect of trial number, the results would suggest that the custom-made sham needles used in this study could be used in cross-over studies and those that use sham needles multiple times, without affecting blinding.
As previously mentioned, there are many factors that influence the blinding of the sham acupuncture needle, including site to site variability in blinding (forearm, lower leg, abdomen, and back); the LI4 on the forearm is reported to be particularly strict in blinding [12,16,18]. In this study, there was no difference between the needling sensation in the LI4 and LI10 located in the forearm. Since no forearm site differences have been observed in previous reports, we conclude that there are no forearm site differences in blinding of the sham needle [19].
In addition, it has been reported that blinding of sham needle relates seeing or not the needling part of acupuncture, but the results were similar to, or better than, those previously reported even though in this study, visual information was blocked by an eye mask [9,16]. Therefore, visual cues are not considered a relevant factor in blinding of the sham needle.
It is considered necessary to pay attention not only to the nature of the subject and the choice of the needling site but also to the explanation and consent in the use of a sham needle before the experiment. In this study, it was explained that either real or sham needles would be used in order to compare the sensations of acupuncture. Since this explanation may have affected blinding of the sham needle, we believe that a design in which the use of a sham needle is not explained beforehand, but is explained and consented to after the fact, may be a more effective way to implement a sham needle.
The custom-made sham needle used in this study had no pedestal or foam device, and they can be compared with traditional needles, and there are no restrictions on the acupuncture site or insertion angle. This sham needle is highly versatile due to its simple design, technique, and its adaptability to crossover trials. In addition, the sham needle used in this study showed higher blinding potential than existing sham needles used in clinical trials, suggesting effective implementation potential. Moreover, the nature of the participants and the needling sites need to be carefully considered when sham needles are used in clinical trials.
The many factors that are involved the blinding of the sham acupuncture needle and the specific factors are unclear. By clarifying the factors involved in the blinding of sham acupuncture needle and the extent to which these factors affect blinding that will be possible to propose optimal conditions for study design, participants, intervention sites, and intervention methods in trials using sham acupuncture needle. Therefore, it is necessary to align the factors involved in the blinding of sham acupuncture needle and to carefully examine each factor.
CONCLUSIONS
This study evaluated the sensations elicited by sham acupuncture needles placed in the LI4 and LI10 regions of the forearm on healthy volunteers with knowledge of and experience with acupuncture. The results showed that sham needle was blinded in 62.5% of participants and that a skin penetration sensation was induced in 62.5% of individuals. However, the sensation elicited by the sham and real needles were not equivalent. Compared to existing sham needles used in clinical trials, the sham needle used in this study showed a higher blinding capacity and is worth being applied to clinical trials. For women, in contrast, the needling sensation elicited by the sham needle was equivalent to that of the real needle. Interestingly, a sex difference was observed in the blinding potential of the sham needle. Clarifying the factors involved in blinding sham acupuncture needle leads to the presentation of the best conditions in studies using sham acupuncture needle, so each factor needs to be examined in detail.
ACKNOWLEDGEMENTS
The authors appreciate Mayumi Ogura, M.A., Teikyo Heisei University, for help with the writing of the manuscript.
FUNDING
The authors received no financial support for the research, authorship, and/or publication of this manuscript.
AUTHORS' CONTRIBUTIONS
Conceptualization: Daiyu Shinohara, Kenji Imai. Investigation: Daiyu Shinohara, Namiki Shinozaki, Ryo Takahashi. Formal analysis: Daiyu Shinohara. Writing – original draft: Daiyu Shinohara. Writing – review & editing: Namiki Shinozaki, Ryo Takahashi, Kenji Imai. Supervision: Kenji Imai.
CONFLICT OF INTEREST
The authors declare no conflict of interest.
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Related articles in JAMS
Article
Research Article
J Acupunct Meridian Stud 2023; 16(1): 30-39
Published online February 28, 2023 https://doi.org/10.51507/j.jams.2023.16.1.30
Copyright © Medical Association of Pharmacopuncture Institute.
Evaluation of Newly Developed Sham Acupuncture Needle with a Special Focus on Needling Sensation: a Randomized Controlled Trial
Daiyu Shinohara1 , Namiki Shinozaki1 , Ryo Takahashi1 , Kenji Imai1,2,3,*
1Department of Acupuncture and Moxibustion, Graduate School of Health Sciences, Teikyo Heisei University, Tokyo, Japan
2Department of Acupuncture and Moxibustion, Faculty of Health Care, Teikyo Heisei University, Tokyo, Japan
3Research Institute of Oriental Medicine, Teikyo Heisei University, Tokyo, Japan
Correspondence to:Kenji Imai
Department of Acupuncture and Moxibustion, Faculty of Health Care, Teikyo Heisei University, Tokyo, Japan
E-mail k.imai@thu.ac.jp
This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
Background: Most non-penetrating sham and placebo acupuncture needles comprise a traditional pedestal for fixing the guide tube that makes these needles difficult to operate independently. We developed a simple sham acupuncture needle to overcome this problem and focused on managing the needling sensation.
Objectives: To ascertain how differently participants feel sham and real needles and to evaluate whether sham needles are effective in clinical trials.
Methods: After enrolling 64 healthy volunteers who had experienced and were knowledgeable about acupuncture, the practitioner randomly used real and sham needles at four sites (bilateral LI4 and LI10) on the participants’ forearms. A custom-made sham blunt stainless acupuncture needle (40 mm, 0.80 mm) that was inserted into a guide tube was used. Immediately after needling, the participants were questioned in regard to their identification of the needle, skin penetration sensation, and de qi.
Results: The sham needle resulted in 62.5% blinding. Inequivalent sensations were elicited by the sham needles compared to the real needles. Women reported similar needling sensations from the sham and real needles.
Conclusion: This study achieved comparatively higher sham-needle blinding and is therefore worthy of use in clinical trials. The mutual independence of the sham needle from the real needle was mediated presumably by interindividual differences among the participants and the needling sites. Sex differences in sensation were likely related to the blinding capability of the sham needle.
Keywords: Sham acupuncture needle, Placebo, Penetration sensation, Clinical trial, Double blind
INTRODUCTION
In randomized controlled trials of acupuncture stimulation and treatment, sham or placebo acupuncture needles are used in the control group [1,2]. Non-penetrating sham and placebo acupuncture needles have been developed by Streitberger and Kleinhenz [3], Park et al. [4], and Takakura and Yajima [5], and the sham needles are designed to be visually and somatosensorily mimic real needles, which inherently blinds the participants to the experimental condition. Accordingly, trials have been conducted to consider the reliability and validity of the sham needles [6-10]. Although useful, these sham and placebo acupuncture needles have a pedestal (flange) for holding the guide tube that induces tactile stimulation of the skin and makes these needles look different from the usual acupuncture treatment needles, which makes it difficult to compare true acupuncture stimulation. The existing sham acupuncture needles are difficult to manufacture and have little versatility. Thus, there is a need for simple and efficient sham acupuncture needles that are designed with a special focus on the needling sensation [11].
This study was conducted to primarily ascertain how differently participants feel sham and real needles to evaluate whether a simple original sham acupuncture needle that has been designed with a special focus on the needling sensation would be effective in clinical trials. In addition, the secondary objective was to compare the needling sensations and examined how the sex, site of insertion, and trial number affected the blinding of sham acupuncture needle.
MATERIALS AND METHODS
1. Trial design
The trial design was a randomized controlled trial that was conducted from October to December 2021.
2. Participants
The participants of this study were 64 healthy volunteers (32 males and 32 females; age: 21.7 ± 1.4 years [mean ± standard deviation]) with former knowledge of and experience with acupuncture who were enrolled from the Department of Acupuncture and Moxibustion at Teikyo Heisei University. Data were collected at Teikyo Heisei University.
This study was approved by the ethics committee of Teikyo Heisei University, Tokyo, Japan (approval number: 2021-024) and was registered in the University Hospital Medical Information Network Clinical Trials Registry (UMIN: 000045923). All participants were provided a written and an oral explanation about the study and the study-related procedures, and written informed consent was obtained. All experiments were conducted in accordance with the principles of the Declaration of Helsinki and have been reported in accordance with the CONSORT and STRICTA guidelines.
3. Sham acupuncture needle
We used custom-made (in-house) sham acupuncture needles made of disinfected stainless acupuncture needles (0.80 mm diameter and 40 mm length; TAIHO Medical Products Co., Ltd.) that were inserted into a custom-made guide tube (Fig. 1). The tip of the sham acupuncture needle was blunted to prevent skin puncture. To match the diameter of the sham acupuncture needle, the guide tube had an inner diameter of 0.80 mm and measured 50-60 mm in length. The sham acupuncture needle was used with a needling technique that involved stabilization of the needle at the needling site (similar to the insertion of a real acupuncture needle; Fig. 2A), followed by subsequent light tapping of the needle head (Fig. 2B), then pulling it out (Fig. 2C), and eliciting stimulation through the tip of the guide tube (Fig. 2D).
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Figure 1. Design of the sham and real acupuncture needles. The left side shows the custom-made sham acupuncture needle (0.80 mm diameter, 40 mm length), the custom-made guide tube (50-60 mm length), and the tip of the sham acupuncture needle. The right side shows the real acupuncture needle (0.20 mm diameter, 40 mm length), the guide tube, and the tip of the real acupuncture needle. The tip of the sham acupuncture needle is blunt so as not to penetrate the skin. The guide tube is made to have an inner diameter of about 0.80 mm to match the diameter of the sham acupuncture needle.
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Figure 2. The needling technique for the sham acupuncture needle. The needling technique for the sham acupuncture needle is shown in A, B, C, and D. Prepare to perform the sham acupuncture needle demonstration by stabilizing the sham acupuncture needle at the needling site, similar to before the insertion of a real acupuncture needle (A). Subsequently lightly tap the head of a needle (B), pull out a needle (C), stimulation by just thin guide tube’s tip (D).
4. Outcome assessments
The primary outcome measure was needle identification whereas the secondary outcome measures were the presence or absence of a skin-penetration sensation and
5. Protocol
The practitioner randomly performed acupuncture with real and sham needles at four sites (bilateral LI4 and LI10) on the forearms of each participant under four set conditions: [A]: LI4 (right) → LI4 (left) → LI10 (right) → LI10 (left); [B]: LI4 (left) → LI4 (right) → LI10 (left) → LI10 (right); [C]: LI10 (right) → LI10 (left) → LI4 (Right) → LI4 (left); and [D]: LI10 (left) → LI10 (right) → LI4 (left) → LI4 (right). Additionally, there were 16 categories for the selection of real and sham needles for each of the four sites. Therefore, the participants were assigned randomly and unbiasedly to 64 categories (4 categories × 16 categories) in this study by using a random number table, with sex as the allocation factor, by individuals who were uninvolved in the conduct of the experiments.
The mean room temperature and humidity were 25.6 ± 1.9℃ and 57.3% ± 9.5%, respectively. Prior to the experiment, the participants were informed that either real or sham acupuncture would be used. The participants wore an eye mask while in a seated position and placed their forearms on the table. The practitioner randomly performed real and sham needle-based acupuncture at four sites of the bilateral LI4 and LI10 for each participant: LI4 was located on the radial aspect, to the midpoint of the second metacarpal bone, and LI10 was located on the posterolateral aspect of the forearm, 60 mm inferior to the cubital crease. A sterile stainless acupuncture needle (diameter, 0.20 mm; length, 40 mm; SEIRIN Co., Shizuoka, Japan) was used for the real acupuncture and was inserted perpendicularly, via a simple insertion technique, to a depth of 15 mm under the skin and then withdrawn immediately. Immediately after performing acupuncture with each needle, the evaluator interviewed the participants about the needle identification and the presence or absence of a skin-penetration sensation and
6. Statistical analysis
JMP® Pro 15.0.0 (SAS Institute Japan Ltd.) was used for all the statistical analysis. Results of the primary and secondary outcome measures are shown in the contingency table. Pearson’s chi-square test was used to ascertain the associations between the two groups.
RESULTS
1. Full data
We analyzed data from 64 participants (256 times, in total) who met the eligibility criteria because there were no losses and exclusions after randomization in each group. The basic attributes at baseline for each group are shown in Table 1. Adverse events resulting from the real acupuncture intervention included bleeding in 5 cases whereas no adverse events were observed with the sham acupuncture intervention.
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Table 1
Baseline demographic and clinical characteristics for each group.
Group Real needle Sham needle LI4-right
(n = 32)LI4-left
(n = 32)LI10-right
(n = 32)LI10-left
(n = 32)LI4-right
(n = 32)LI4-left
(n = 32)LI10-right
(n = 32)LI10-left
(n = 32)Male/Female 18/14 17/15 16/16 15/17 14/18 15/17 16/16 17/15 Age (mean ± SD) 21.8 ± 1.5 21.8 ± 1.4 21.7 ± 1.4 21.8 ± 1.2 21.7 ± 1.4 21.7 ± 1.5 21.7 ± 1.4 21.7 ± 1.6
Needles were tested at four sites (bilateral LI4 and LI10) on 64 participants. Therefore, data from a total of 256 sessions are shown in Table 2A. For the sham needles, “Felt real” was reported 18 times (14.1%), “Maybe felt real” was reported 52 times (40.6%), “Didn’t know” was reported 10 times (7.8%), “Maybe felt fake” was reported 32 times (25.0%), and “Felt fake” was reported 16 times (12.5%) (Table 2A). Moreover, the correct and incorrect answers for sham needles were determined as 48 and 80 times, respectively (incorrect answer rate: 62.5%; Table 2B). In contrast, correct and incorrect answers for real needles were obtained 99 and 29 times, respectively (correct answer rate of 77.3%; Table 2B). According to these results, the sham needle showed 62.5% blinding potential, which was close to the rate of correct answers for the real needle.
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(A). The result about the identification of real and sham needles by subjects.
Felt a real Maybe felt a real Didn’t know Maybe felt a fake Felt a fake Total Real needle 63 (49.2%) 36 (28.1%) 5 (3.9%) 20 (15.6%) 4 (3.1%) 128 Sham needle 18 (14.1%) 52 (40.6%) 10 (7.8%) 32 (25.0%) 16 (12.5%) 128 Total 81 88 15 52 20 256 (B). Correctly answered rate of real needle and incorrectly answered rate of sham needle.
Correct Incorrect Correctly answered (rate) Real needle 99 (Felt a real + Maybe) 29 (Felt a fake + Maybe+ Didn’t know) 99/128 (77.3%) Correct Incorrect Incorrectly answered (rate) Sham needle 48 (Felt a fake + Maybe) 80 (Felt a real + Maybe + Didn’t know) 80/128 (62.5%) (C). Comparison of the identification of needle, skin penetration sensation and
de qi .Correct or incorrect Felt a real Felt a fake Total Real needle 99 24 123 Sham needle 70 48 118 Total 169 72 241 Pearson χ2 test: χ2 = 12.878, df = 1, p < 0.001Skin penetration sensation Felt Didn’t feel Total Real needle 101 (78.9%) 27 (21.1%) 128 Sham needle 80 (62.5%) 48 (37.5%) 128 Total 181 75 256 Pearson χ2 test: χ2 = 8.316, df = 1, p = 0.0039De qi Felt Didn’t feel Total Real needle 45 (35.2%) 83 (64.8%) 128 Sham needle 17 (13.3%) 111 (86.7%) 128 Total 62 194 256 Pearson χ2 test: χ2 = 16.686, df = 1, p < 0.001(D). Comparison of gender when sham needles were performed.
Correct or incorrect Felt a real Felt a fake Total Male 28 29 57 Female 42 19 61 Total 70 48 118 Pearson χ2 test: χ2 = 4.753, df = 1, p = 0.029Skin penetration sensation Felt Didn’t feel Total Male 31 (50.0%) 31 (50.0%) 62 Female 49 (74.2%) 17 (25.8%) 66 Total 80 48 128 Pearson χ2 test: χ2 = 8.016, df = 1, p = 0.0046De qi Felt Didn’t feel Total Male 6 (9.7%) 56 (90.3%) 62 Female 11 (16.7%) 55 (83.3%) 66 Total 17 111 128 Pearson χ2 test: χ2 = 1.356, df = 1, p = 0.24(E). Comparison of the identification of needle, skin penetration sensation and
de qi in male.Correct or incorrect Felt a real Felt a fake Total Real needle 49 14 63 Sham needle 28 29 57 Total 77 43 120 Pearson χ2 test: χ2 = 10.687, df = 1, p = 0.0011Skin penetration sensation Felt Didn’t feel Total Real needle 49 (74.2%) 17 (25.8%) 66 Sham needle 31 (50.0%) 31 (50.0%) 62 Total 80 48 128 Pearson χ2 test: χ2 = 8.016, df = 1, p = 0.0046De qi Felt Didn’t feel Total Real needle 22 (33.3%) 44 (66.7%) 66 Sham needle 6 (9.7%) 56 (90.3%) 62 Total 28 100 128 Pearson χ2 test: χ2 = 10.468, df = 1, p = 0.0012(F). Comparison of the identification of needle, skin penetration sensation and
de qi in female.Correct or incorrect Felt a real Felt a fake Total Real needle 50 10 60 Sham needle 42 19 61 Total 92 29 121 Pearson χ2 test: χ2 = 3.481, df = 1, p = 0.062Skin penetration sensation Felt Didn’t feel Total Real needle 52 (83.9%) 10 (16.1%) 62 Sham needle 49 (74.2%) 17 (25.8%) 66 Total 101 27 128 Pearson χ2 test: χ2 = 1.781, df = 1, p = 0.18De qi Felt Didn’t feel Total Real needle 23 (37.1%) 39 (62.9%) 62 Sham needle 11 (16.7%) 55 (83.3%) 66 Total 34 94 128 Pearson χ2 test: χ2 = 6.840, df = 1, p = 0.0089(G). Comparison of LI4 and LI10 when sham needles were performed.
Correct or incorrect Felt a real Felt a fake Total LI4 40 21 61 LI10 30 27 57 Total 70 48 118 Pearson χ2 test: χ2 = 2.045, df = 1, p = 0.15Skin penetration sensation Felt Didn’t feel Total LI4 45 (70.3%) 19 (29.7%) 64 LI10 35 (54.7%) 29 (45.3%) 64 Total 80 48 128 Pearson χ2 test: χ2 = 3.333, df = 1, p = 0.068De qi Felt Didn’t feel Total LI4 9 (14.1%) 55 (85.9%) 64 LI10 8 (12.5%) 56 (87.5%) 64 Total 17 111 128 Pearson χ2 test: χ2 = 0.068, df = 1, p = 0.79(H). Comparison of the trial nums when sham needles were performed.
Correct or incorrect Felt a real Felt a fake Total 1st 18 13 31 2nd 18 11 29 3rd 14 16 30 4th 20 8 28 Total 70 48 118 Pearson χ2 test: χ2 = 3.803, df = 3, p = 0.28Skin penetration sensation Felt Didn’t feel Total 1st 20 (62.5%) 12 (37.5%) 32 2nd 21 (65.6%) 11 (34.4%) 32 3rd 18 (56.3%) 14 (43.7%) 32 4th 21 (65.6%) 11 (34.4%) 32 Total 80 48 128 Pearson χ2 test: χ2 = 0.800, df = 3, p = 0.84De qi Felt Didn’t feel Total 1st 4 (12.5%) 28 (87.5%) 32 2nd 3 (9.4%) 29 (90.6%) 32 3rd 6 (18.8%) 26 (81.2%) 32 4th 4 (12.5%) 28 (87.5%) 32 Total 17 111 128 Pearson χ2 test: χ2 = 1.3289, df = 3, p = 0.73df = degrees of freedom..
The results of the identification and sensation by subjects.
(A). The result about the identification of real and sham needles by subjects.
Felt a real Maybe felt a real Didn’t know Maybe felt a fake Felt a fake Total Real needle 63 (49.2%) 36 (28.1%) 5 (3.9%) 20 (15.6%) 4 (3.1%) 128 Sham needle 18 (14.1%) 52 (40.6%) 10 (7.8%) 32 (25.0%) 16 (12.5%) 128 Total 81 88 15 52 20 256 (B). Correctly answered rate of real needle and incorrectly answered rate of sham needle.
Correct Incorrect Correctly answered (rate) Real needle 99 (Felt a real + Maybe) 29 (Felt a fake + Maybe+ Didn’t know) 99/128 (77.3%) Correct Incorrect Incorrectly answered (rate) Sham needle 48 (Felt a fake + Maybe) 80 (Felt a real + Maybe + Didn’t know) 80/128 (62.5%) (C). Comparison of the identification of needle, skin penetration sensation and
de qi .Correct or incorrect Felt a real Felt a fake Total Real needle 99 24 123 Sham needle 70 48 118 Total 169 72 241 Pearson χ2 test: χ2 = 12.878, df = 1, p < 0.001Skin penetration sensation Felt Didn’t feel Total Real needle 101 (78.9%) 27 (21.1%) 128 Sham needle 80 (62.5%) 48 (37.5%) 128 Total 181 75 256 Pearson χ2 test: χ2 = 8.316, df = 1, p = 0.0039De qi Felt Didn’t feel Total Real needle 45 (35.2%) 83 (64.8%) 128 Sham needle 17 (13.3%) 111 (86.7%) 128 Total 62 194 256 Pearson χ2 test: χ2 = 16.686, df = 1, p < 0.001(D). Comparison of gender when sham needles were performed.
Correct or incorrect Felt a real Felt a fake Total Male 28 29 57 Female 42 19 61 Total 70 48 118 Pearson χ2 test: χ2 = 4.753, df = 1, p = 0.029Skin penetration sensation Felt Didn’t feel Total Male 31 (50.0%) 31 (50.0%) 62 Female 49 (74.2%) 17 (25.8%) 66 Total 80 48 128 Pearson χ2 test: χ2 = 8.016, df = 1, p = 0.0046De qi Felt Didn’t feel Total Male 6 (9.7%) 56 (90.3%) 62 Female 11 (16.7%) 55 (83.3%) 66 Total 17 111 128 Pearson χ2 test: χ2 = 1.356, df = 1, p = 0.24(E). Comparison of the identification of needle, skin penetration sensation and
de qi in male.Correct or incorrect Felt a real Felt a fake Total Real needle 49 14 63 Sham needle 28 29 57 Total 77 43 120 Pearson χ2 test: χ2 = 10.687, df = 1, p = 0.0011Skin penetration sensation Felt Didn’t feel Total Real needle 49 (74.2%) 17 (25.8%) 66 Sham needle 31 (50.0%) 31 (50.0%) 62 Total 80 48 128 Pearson χ2 test: χ2 = 8.016, df = 1, p = 0.0046De qi Felt Didn’t feel Total Real needle 22 (33.3%) 44 (66.7%) 66 Sham needle 6 (9.7%) 56 (90.3%) 62 Total 28 100 128 Pearson χ2 test: χ2 = 10.468, df = 1, p = 0.0012(F). Comparison of the identification of needle, skin penetration sensation and
de qi in female.Correct or incorrect Felt a real Felt a fake Total Real needle 50 10 60 Sham needle 42 19 61 Total 92 29 121 Pearson χ2 test: χ2 = 3.481, df = 1, p = 0.062Skin penetration sensation Felt Didn’t feel Total Real needle 52 (83.9%) 10 (16.1%) 62 Sham needle 49 (74.2%) 17 (25.8%) 66 Total 101 27 128 Pearson χ2 test: χ2 = 1.781, df = 1, p = 0.18De qi Felt Didn’t feel Total Real needle 23 (37.1%) 39 (62.9%) 62 Sham needle 11 (16.7%) 55 (83.3%) 66 Total 34 94 128 Pearson χ2 test: χ2 = 6.840, df = 1, p = 0.0089(G). Comparison of LI4 and LI10 when sham needles were performed.
Correct or incorrect Felt a real Felt a fake Total LI4 40 21 61 LI10 30 27 57 Total 70 48 118 Pearson χ2 test: χ2 = 2.045, df = 1, p = 0.15Skin penetration sensation Felt Didn’t feel Total LI4 45 (70.3%) 19 (29.7%) 64 LI10 35 (54.7%) 29 (45.3%) 64 Total 80 48 128 Pearson χ2 test: χ2 = 3.333, df = 1, p = 0.068De qi Felt Didn’t feel Total LI4 9 (14.1%) 55 (85.9%) 64 LI10 8 (12.5%) 56 (87.5%) 64 Total 17 111 128 Pearson χ2 test: χ2 = 0.068, df = 1, p = 0.79(H). Comparison of the trial nums when sham needles were performed.
Correct or incorrect Felt a real Felt a fake Total 1st 18 13 31 2nd 18 11 29 3rd 14 16 30 4th 20 8 28 Total 70 48 118 Pearson χ2 test: χ2 = 3.803, df = 3, p = 0.28Skin penetration sensation Felt Didn’t feel Total 1st 20 (62.5%) 12 (37.5%) 32 2nd 21 (65.6%) 11 (34.4%) 32 3rd 18 (56.3%) 14 (43.7%) 32 4th 21 (65.6%) 11 (34.4%) 32 Total 80 48 128 Pearson χ2 test: χ2 = 0.800, df = 3, p = 0.84De qi Felt Didn’t feel Total 1st 4 (12.5%) 28 (87.5%) 32 2nd 3 (9.4%) 29 (90.6%) 32 3rd 6 (18.8%) 26 (81.2%) 32 4th 4 (12.5%) 28 (87.5%) 32 Total 17 111 128 Pearson χ2 test: χ2 = 1.3289, df = 3, p = 0.73df = degrees of freedom..
2. Differences in identification and sensations between sham and real needles
To evaluate the difference in the stimulation sensation between the sham and real needles, we compared the reported needle identification, skin-penetration sensation, and
3. Sex difference in the sham needle outcomes
To evaluate sex differences in the needling sensation elicited by a sham needle, we compared the sham needle identification, skin-penetration sensation, and
As such, we analyzed the differences in needling sensation between real and sham needles separately for men and women (Tables 2E and 2F). For men, real and sham needles were non-independent across all outcomes (identification, skin-penetration sensation, and
4. Differences in the sham effect between forearm sites, LI4 and LI10
To evaluate the differences in sham needle-needling sensation on the forearms, we compared the rate of needle identification, skin-penetration sensation, and
Additionally, the number of incorrect answers and the incorrect answer rate for sham needles in the LI4 were 43 times and 67.2%, respectively, and the number of incorrect answers and the incorrect answer rate for sham needles in the LI10 were 37 times and 57.8%, respectively.
5. Differences in the influence of trial number on sham needle-elicited sensations
To evaluate the differences in sham-needle needling sensation as a function of trial number, we compared needle identification, skin penetration sensation, and
DISCUSSION
This study evaluated the sensation that sham acupuncture needles elicit at the LI4 and LI10 sites of the forearm in healthy volunteers with knowledge of and experience with acupuncture. The results showed that the sham needle conferred 62.5% blinding potential and induced a skin-penetration sensation in 62.5% of the participants. However, the sensations elicited by sham and real needles were not equivalent. In contrast, in women, the needling sensation from the sham needle was equivalent to that of a real needle. Therefore, it was shown that blinding capacity of the sham needle was influenced by sex.
The overall data and the separate LI4 and LI10 sham needle results show a blinding rate of 62.5% (80/128), 67.2% (43/64), and 57.8% (37/64), respectively. Previous studies that compared and evaluated the validity of sham and placebo acupuncture needles have been conducted under various conditions, using various indices [11,12]. Similar to this study, the blinding rate of sham needles for LI4 was reported by White et al. as 50.0% (10/20) [13], by Chae et al. as 14.3% (2/14) [14], and by Lee et al. as 55.0% (22/40) [15]. Moreover, a study conducted on healthy volunteers with knowledge and experience with acupuncture showed 56.1% (64/114) blinding at different needling sites [8]. Therefore, compared to existing sham needles that are used in clinical trials, the sham needle used in this study showed a higher blinding capacity and is worth being applied to clinical trials.
Factors that influence the blinding of sham acupuncture needles include the participant’s mental and physical state, race, acupuncture experience and knowledge, acupuncture point selection (upper/lower extremities or back), and the appearance of the needles (visual impact) [12,13,16]. When using the sham needle, blinding may not be as efficient in healthy participants compared to that in patients. Moreover, blinding may not be as efficient in participants with experience and knowledge of acupuncture, and in placement into the LI4 of the forearm [12]. In this study, all evaluations under stringent conditions were conducted to use sham needles and were focused on needling sensation. However, the needling sensation by sham and real needles was not equivalent. The results of this study are targeting both the LI4 and LI10 sites of the forearms in healthy volunteers with knowledge of and experience with acupuncture. In a previous study, it has been reported that even participants with experience and knowledge of acupuncture can be blinded by needling in less sensitive sites. Therefore, it is thought that the sham needle is possible to induce a needling sensation equivalent to real needle depending on the needling sites (i.e., the lower limbs and the lumbar regions).
Furthermore, the recognition of a skin-penetration sensation was observed to be strongly involved in the identification of acupuncture stimulation. Takakura and Yajima [8] report that skin penetration/penetration-like pain would be the main factor that influences identification of acupuncture needle. Therefore, in this study, it is also considered that, compared to the
One important finding of this study was that in females, the sham-needle needling sensation was equivalent to that induced by the real needle. Sex differences have not been previously reported and could not be compared to previous studies. Differences in pain thresholds between males and female were considered as a potential factor explaining the gender difference in blinding of the sham needle. Indeed, Lue et al. [17] reported higher thermal pain thresholds in males compared to females. Furthermore, the stimulation of the skin by the tip of the sham needle may cause excitation of not only group II fibers but also group III and IV fibers, depending on the structure and degree of stimulation, thereby inducing a real needle-like skin penetration sensation. Therefore, it is suggested that the blinding of sham needles was higher in females with a low thermal threshold, giving a sensation equivalent to that of real needles.
The effect of trial number using sham needles was evaluated and not found to be involved in the blinding capacity of the sham needle. There are reports that sham needle research is not suitable for crossover designs, and that the involvement of trial numbers is unclear [10,18]. However, given the lack of an effect of trial number, the results would suggest that the custom-made sham needles used in this study could be used in cross-over studies and those that use sham needles multiple times, without affecting blinding.
As previously mentioned, there are many factors that influence the blinding of the sham acupuncture needle, including site to site variability in blinding (forearm, lower leg, abdomen, and back); the LI4 on the forearm is reported to be particularly strict in blinding [12,16,18]. In this study, there was no difference between the needling sensation in the LI4 and LI10 located in the forearm. Since no forearm site differences have been observed in previous reports, we conclude that there are no forearm site differences in blinding of the sham needle [19].
In addition, it has been reported that blinding of sham needle relates seeing or not the needling part of acupuncture, but the results were similar to, or better than, those previously reported even though in this study, visual information was blocked by an eye mask [9,16]. Therefore, visual cues are not considered a relevant factor in blinding of the sham needle.
It is considered necessary to pay attention not only to the nature of the subject and the choice of the needling site but also to the explanation and consent in the use of a sham needle before the experiment. In this study, it was explained that either real or sham needles would be used in order to compare the sensations of acupuncture. Since this explanation may have affected blinding of the sham needle, we believe that a design in which the use of a sham needle is not explained beforehand, but is explained and consented to after the fact, may be a more effective way to implement a sham needle.
The custom-made sham needle used in this study had no pedestal or foam device, and they can be compared with traditional needles, and there are no restrictions on the acupuncture site or insertion angle. This sham needle is highly versatile due to its simple design, technique, and its adaptability to crossover trials. In addition, the sham needle used in this study showed higher blinding potential than existing sham needles used in clinical trials, suggesting effective implementation potential. Moreover, the nature of the participants and the needling sites need to be carefully considered when sham needles are used in clinical trials.
The many factors that are involved the blinding of the sham acupuncture needle and the specific factors are unclear. By clarifying the factors involved in the blinding of sham acupuncture needle and the extent to which these factors affect blinding that will be possible to propose optimal conditions for study design, participants, intervention sites, and intervention methods in trials using sham acupuncture needle. Therefore, it is necessary to align the factors involved in the blinding of sham acupuncture needle and to carefully examine each factor.
CONCLUSIONS
This study evaluated the sensations elicited by sham acupuncture needles placed in the LI4 and LI10 regions of the forearm on healthy volunteers with knowledge of and experience with acupuncture. The results showed that sham needle was blinded in 62.5% of participants and that a skin penetration sensation was induced in 62.5% of individuals. However, the sensation elicited by the sham and real needles were not equivalent. Compared to existing sham needles used in clinical trials, the sham needle used in this study showed a higher blinding capacity and is worth being applied to clinical trials. For women, in contrast, the needling sensation elicited by the sham needle was equivalent to that of the real needle. Interestingly, a sex difference was observed in the blinding potential of the sham needle. Clarifying the factors involved in blinding sham acupuncture needle leads to the presentation of the best conditions in studies using sham acupuncture needle, so each factor needs to be examined in detail.
ACKNOWLEDGEMENTS
The authors appreciate Mayumi Ogura, M.A., Teikyo Heisei University, for help with the writing of the manuscript.
FUNDING
The authors received no financial support for the research, authorship, and/or publication of this manuscript.
AUTHORS' CONTRIBUTIONS
Conceptualization: Daiyu Shinohara, Kenji Imai. Investigation: Daiyu Shinohara, Namiki Shinozaki, Ryo Takahashi. Formal analysis: Daiyu Shinohara. Writing – original draft: Daiyu Shinohara. Writing – review & editing: Namiki Shinozaki, Ryo Takahashi, Kenji Imai. Supervision: Kenji Imai.
CONFLICT OF INTEREST
The authors declare no conflict of interest.
Fig 1.
Fig 2.
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Table 1 . Baseline demographic and clinical characteristics for each group.
Group Real needle Sham needle LI4-right
(n = 32)LI4-left
(n = 32)LI10-right
(n = 32)LI10-left
(n = 32)LI4-right
(n = 32)LI4-left
(n = 32)LI10-right
(n = 32)LI10-left
(n = 32)Male/Female 18/14 17/15 16/16 15/17 14/18 15/17 16/16 17/15 Age (mean ± SD) 21.8 ± 1.5 21.8 ± 1.4 21.7 ± 1.4 21.8 ± 1.2 21.7 ± 1.4 21.7 ± 1.5 21.7 ± 1.4 21.7 ± 1.6
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Table 2 . The results of the identification and sensation by subjects.
(A). The result about the identification of real and sham needles by subjects.
Felt a real Maybe felt a real Didn’t know Maybe felt a fake Felt a fake Total Real needle 63 (49.2%) 36 (28.1%) 5 (3.9%) 20 (15.6%) 4 (3.1%) 128 Sham needle 18 (14.1%) 52 (40.6%) 10 (7.8%) 32 (25.0%) 16 (12.5%) 128 Total 81 88 15 52 20 256 (B). Correctly answered rate of real needle and incorrectly answered rate of sham needle.
Correct Incorrect Correctly answered (rate) Real needle 99 (Felt a real + Maybe) 29 (Felt a fake + Maybe+ Didn’t know) 99/128 (77.3%) Correct Incorrect Incorrectly answered (rate) Sham needle 48 (Felt a fake + Maybe) 80 (Felt a real + Maybe + Didn’t know) 80/128 (62.5%) (C). Comparison of the identification of needle, skin penetration sensation and
de qi .Correct or incorrect Felt a real Felt a fake Total Real needle 99 24 123 Sham needle 70 48 118 Total 169 72 241 Pearson χ2 test: χ2 = 12.878, df = 1, p < 0.001Skin penetration sensation Felt Didn’t feel Total Real needle 101 (78.9%) 27 (21.1%) 128 Sham needle 80 (62.5%) 48 (37.5%) 128 Total 181 75 256 Pearson χ2 test: χ2 = 8.316, df = 1, p = 0.0039De qi Felt Didn’t feel Total Real needle 45 (35.2%) 83 (64.8%) 128 Sham needle 17 (13.3%) 111 (86.7%) 128 Total 62 194 256 Pearson χ2 test: χ2 = 16.686, df = 1, p < 0.001(D). Comparison of gender when sham needles were performed.
Correct or incorrect Felt a real Felt a fake Total Male 28 29 57 Female 42 19 61 Total 70 48 118 Pearson χ2 test: χ2 = 4.753, df = 1, p = 0.029Skin penetration sensation Felt Didn’t feel Total Male 31 (50.0%) 31 (50.0%) 62 Female 49 (74.2%) 17 (25.8%) 66 Total 80 48 128 Pearson χ2 test: χ2 = 8.016, df = 1, p = 0.0046De qi Felt Didn’t feel Total Male 6 (9.7%) 56 (90.3%) 62 Female 11 (16.7%) 55 (83.3%) 66 Total 17 111 128 Pearson χ2 test: χ2 = 1.356, df = 1, p = 0.24(E). Comparison of the identification of needle, skin penetration sensation and
de qi in male.Correct or incorrect Felt a real Felt a fake Total Real needle 49 14 63 Sham needle 28 29 57 Total 77 43 120 Pearson χ2 test: χ2 = 10.687, df = 1, p = 0.0011Skin penetration sensation Felt Didn’t feel Total Real needle 49 (74.2%) 17 (25.8%) 66 Sham needle 31 (50.0%) 31 (50.0%) 62 Total 80 48 128 Pearson χ2 test: χ2 = 8.016, df = 1, p = 0.0046De qi Felt Didn’t feel Total Real needle 22 (33.3%) 44 (66.7%) 66 Sham needle 6 (9.7%) 56 (90.3%) 62 Total 28 100 128 Pearson χ2 test: χ2 = 10.468, df = 1, p = 0.0012(F). Comparison of the identification of needle, skin penetration sensation and
de qi in female.Correct or incorrect Felt a real Felt a fake Total Real needle 50 10 60 Sham needle 42 19 61 Total 92 29 121 Pearson χ2 test: χ2 = 3.481, df = 1, p = 0.062Skin penetration sensation Felt Didn’t feel Total Real needle 52 (83.9%) 10 (16.1%) 62 Sham needle 49 (74.2%) 17 (25.8%) 66 Total 101 27 128 Pearson χ2 test: χ2 = 1.781, df = 1, p = 0.18De qi Felt Didn’t feel Total Real needle 23 (37.1%) 39 (62.9%) 62 Sham needle 11 (16.7%) 55 (83.3%) 66 Total 34 94 128 Pearson χ2 test: χ2 = 6.840, df = 1, p = 0.0089(G). Comparison of LI4 and LI10 when sham needles were performed.
Correct or incorrect Felt a real Felt a fake Total LI4 40 21 61 LI10 30 27 57 Total 70 48 118 Pearson χ2 test: χ2 = 2.045, df = 1, p = 0.15Skin penetration sensation Felt Didn’t feel Total LI4 45 (70.3%) 19 (29.7%) 64 LI10 35 (54.7%) 29 (45.3%) 64 Total 80 48 128 Pearson χ2 test: χ2 = 3.333, df = 1, p = 0.068De qi Felt Didn’t feel Total LI4 9 (14.1%) 55 (85.9%) 64 LI10 8 (12.5%) 56 (87.5%) 64 Total 17 111 128 Pearson χ2 test: χ2 = 0.068, df = 1, p = 0.79(H). Comparison of the trial nums when sham needles were performed.
Correct or incorrect Felt a real Felt a fake Total 1st 18 13 31 2nd 18 11 29 3rd 14 16 30 4th 20 8 28 Total 70 48 118 Pearson χ2 test: χ2 = 3.803, df = 3, p = 0.28Skin penetration sensation Felt Didn’t feel Total 1st 20 (62.5%) 12 (37.5%) 32 2nd 21 (65.6%) 11 (34.4%) 32 3rd 18 (56.3%) 14 (43.7%) 32 4th 21 (65.6%) 11 (34.4%) 32 Total 80 48 128 Pearson χ2 test: χ2 = 0.800, df = 3, p = 0.84De qi Felt Didn’t feel Total 1st 4 (12.5%) 28 (87.5%) 32 2nd 3 (9.4%) 29 (90.6%) 32 3rd 6 (18.8%) 26 (81.2%) 32 4th 4 (12.5%) 28 (87.5%) 32 Total 17 111 128 Pearson χ2 test: χ2 = 1.3289, df = 3, p = 0.73df = degrees of freedom..
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