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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

Received: April 12, 2022; Revised: August 26, 2022; Accepted: January 26, 2023

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).

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.

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 de qi. Immediately after having undergone acupuncture with the indicated needle, the participants reported their experience and perception of the real or sham needle on a 5-level scale (“Felt real”, “Maybe felt real”, “Didn’t know”, “Maybe felt fake” and “Felt fake”) and whether they experienced the presence of a skin-penetration sensation. Additionally, the real and/or sham acupuncture sensation of de qi had been evaluated in all participants.

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 de qi, during the session. Experimental double-blinding was achieved by having only the practitioner know the sham and/or real needle conditions; the evaluator and participants learned of their respective groups only after the experiment. Additionally, the data were analyzed after all the experiments were completed.

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.

Table 1

Baseline demographic and clinical characteristics for each group.

GroupReal needleSham 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/Female18/1417/1516/1615/1714/1815/1716/1617/15
Age (mean ± SD)21.8 ± 1.521.8 ± 1.421.7 ± 1.421.8 ± 1.221.7 ± 1.421.7 ± 1.521.7 ± 1.421.7 ± 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.

(A). The result about the identification of real and sham needles by subjects.

Felt a realMaybe felt a realDidn’t knowMaybe felt a fakeFelt a fakeTotal
Real needle63 (49.2%)36 (28.1%)5 (3.9%)20 (15.6%)4 (3.1%)128
Sham needle18 (14.1%)52 (40.6%)10 (7.8%)32 (25.0%)16 (12.5%)128
Total8188155220256

(B). Correctly answered rate of real needle and incorrectly answered rate of sham needle.

CorrectIncorrectCorrectly answered (rate)
Real needle99 (Felt a real + Maybe)29 (Felt a fake + Maybe+ Didn’t know)99/128 (77.3%)
CorrectIncorrectIncorrectly answered (rate)
Sham needle48 (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 incorrectFelt a realFelt a fakeTotal
Real needle9924123
Sham needle7048118
Total16972241
Pearson χ2 test: χ2 = 12.878, df = 1, p < 0.001
Skin penetration sensationFeltDidn’t feelTotal
Real needle101 (78.9%)27 (21.1%)128
Sham needle80 (62.5%)48 (37.5%)128
Total18175256
Pearson χ2 test: χ2 = 8.316, df = 1, p = 0.0039
De qiFeltDidn’t feelTotal
Real needle45 (35.2%)83 (64.8%)128
Sham needle17 (13.3%)111 (86.7%)128
Total62194256
Pearson χ2 test: χ2 = 16.686, df = 1, p < 0.001

(D). Comparison of gender when sham needles were performed.

Correct or incorrectFelt a realFelt a fakeTotal
Male282957
Female421961
Total7048118
Pearson χ2 test: χ2 = 4.753, df = 1, p = 0.029
Skin penetration sensationFeltDidn’t feelTotal
Male31 (50.0%)31 (50.0%)62
Female49 (74.2%)17 (25.8%)66
Total8048128
Pearson χ2 test: χ2 = 8.016, df = 1, p = 0.0046
De qiFeltDidn’t feelTotal
Male6 (9.7%)56 (90.3%)62
Female11 (16.7%)55 (83.3%)66
Total17111128
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 incorrectFelt a realFelt a fakeTotal
Real needle491463
Sham needle282957
Total7743120
Pearson χ2 test: χ2 = 10.687, df = 1, p = 0.0011
Skin penetration sensationFeltDidn’t feelTotal
Real needle49 (74.2%)17 (25.8%)66
Sham needle31 (50.0%)31 (50.0%)62
Total8048128
Pearson χ2 test: χ2 = 8.016, df = 1, p = 0.0046
De qiFeltDidn’t feelTotal
Real needle22 (33.3%)44 (66.7%)66
Sham needle6 (9.7%)56 (90.3%)62
Total28100128
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 incorrectFelt a realFelt a fakeTotal
Real needle501060
Sham needle421961
Total9229121
Pearson χ2 test: χ2 = 3.481, df = 1, p = 0.062
Skin penetration sensationFeltDidn’t feelTotal
Real needle52 (83.9%)10 (16.1%)62
Sham needle49 (74.2%)17 (25.8%)66
Total10127128
Pearson χ2 test: χ2 = 1.781, df = 1, p = 0.18
De qiFeltDidn’t feelTotal
Real needle23 (37.1%)39 (62.9%)62
Sham needle11 (16.7%)55 (83.3%)66
Total3494128
Pearson χ2 test: χ2 = 6.840, df = 1, p = 0.0089

(G). Comparison of LI4 and LI10 when sham needles were performed.

Correct or incorrectFelt a realFelt a fakeTotal
LI4402161
LI10302757
Total7048118
Pearson χ2 test: χ2 = 2.045, df = 1, p = 0.15
Skin penetration sensationFeltDidn’t feelTotal
LI445 (70.3%)19 (29.7%)64
LI1035 (54.7%)29 (45.3%)64
Total8048128
Pearson χ2 test: χ2 = 3.333, df = 1, p = 0.068
De qiFeltDidn’t feelTotal
LI49 (14.1%)55 (85.9%)64
LI108 (12.5%)56 (87.5%)64
Total17111128
Pearson χ2 test: χ2 = 0.068, df = 1, p = 0.79

(H). Comparison of the trial nums when sham needles were performed.

Correct or incorrectFelt a realFelt a fakeTotal
1st181331
2nd181129
3rd141630
4th20828
Total7048118
Pearson χ2 test: χ2 = 3.803, df = 3, p = 0.28
Skin penetration sensationFeltDidn’t feelTotal
1st20 (62.5%)12 (37.5%)32
2nd21 (65.6%)11 (34.4%)32
3rd18 (56.3%)14 (43.7%)32
4th21 (65.6%)11 (34.4%)32
Total8048128
Pearson χ2 test: χ2 = 0.800, df = 3, p = 0.84
De qiFeltDidn’t feelTotal
1st4 (12.5%)28 (87.5%)32
2nd3 (9.4%)29 (90.6%)32
3rd6 (18.8%)26 (81.2%)32
4th4 (12.5%)28 (87.5%)32
Total17111128
Pearson χ2 test: χ2 = 1.3289, df = 3, p = 0.73

df = degrees of freedom..

&md=tbl&idx=2' data-target="#file-modal"">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 realMaybe felt a realDidn’t knowMaybe felt a fakeFelt a fakeTotal
Real needle63 (49.2%)36 (28.1%)5 (3.9%)20 (15.6%)4 (3.1%)128
Sham needle18 (14.1%)52 (40.6%)10 (7.8%)32 (25.0%)16 (12.5%)128
Total8188155220256

(B). Correctly answered rate of real needle and incorrectly answered rate of sham needle.

CorrectIncorrectCorrectly answered (rate)
Real needle99 (Felt a real + Maybe)29 (Felt a fake + Maybe+ Didn’t know)99/128 (77.3%)
CorrectIncorrectIncorrectly answered (rate)
Sham needle48 (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 incorrectFelt a realFelt a fakeTotal
Real needle9924123
Sham needle7048118
Total16972241
Pearson χ2 test: χ2 = 12.878, df = 1, p < 0.001
Skin penetration sensationFeltDidn’t feelTotal
Real needle101 (78.9%)27 (21.1%)128
Sham needle80 (62.5%)48 (37.5%)128
Total18175256
Pearson χ2 test: χ2 = 8.316, df = 1, p = 0.0039
De qiFeltDidn’t feelTotal
Real needle45 (35.2%)83 (64.8%)128
Sham needle17 (13.3%)111 (86.7%)128
Total62194256
Pearson χ2 test: χ2 = 16.686, df = 1, p < 0.001

(D). Comparison of gender when sham needles were performed.

Correct or incorrectFelt a realFelt a fakeTotal
Male282957
Female421961
Total7048118
Pearson χ2 test: χ2 = 4.753, df = 1, p = 0.029
Skin penetration sensationFeltDidn’t feelTotal
Male31 (50.0%)31 (50.0%)62
Female49 (74.2%)17 (25.8%)66
Total8048128
Pearson χ2 test: χ2 = 8.016, df = 1, p = 0.0046
De qiFeltDidn’t feelTotal
Male6 (9.7%)56 (90.3%)62
Female11 (16.7%)55 (83.3%)66
Total17111128
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 incorrectFelt a realFelt a fakeTotal
Real needle491463
Sham needle282957
Total7743120
Pearson χ2 test: χ2 = 10.687, df = 1, p = 0.0011
Skin penetration sensationFeltDidn’t feelTotal
Real needle49 (74.2%)17 (25.8%)66
Sham needle31 (50.0%)31 (50.0%)62
Total8048128
Pearson χ2 test: χ2 = 8.016, df = 1, p = 0.0046
De qiFeltDidn’t feelTotal
Real needle22 (33.3%)44 (66.7%)66
Sham needle6 (9.7%)56 (90.3%)62
Total28100128
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 incorrectFelt a realFelt a fakeTotal
Real needle501060
Sham needle421961
Total9229121
Pearson χ2 test: χ2 = 3.481, df = 1, p = 0.062
Skin penetration sensationFeltDidn’t feelTotal
Real needle52 (83.9%)10 (16.1%)62
Sham needle49 (74.2%)17 (25.8%)66
Total10127128
Pearson χ2 test: χ2 = 1.781, df = 1, p = 0.18
De qiFeltDidn’t feelTotal
Real needle23 (37.1%)39 (62.9%)62
Sham needle11 (16.7%)55 (83.3%)66
Total3494128
Pearson χ2 test: χ2 = 6.840, df = 1, p = 0.0089

(G). Comparison of LI4 and LI10 when sham needles were performed.

Correct or incorrectFelt a realFelt a fakeTotal
LI4402161
LI10302757
Total7048118
Pearson χ2 test: χ2 = 2.045, df = 1, p = 0.15
Skin penetration sensationFeltDidn’t feelTotal
LI445 (70.3%)19 (29.7%)64
LI1035 (54.7%)29 (45.3%)64
Total8048128
Pearson χ2 test: χ2 = 3.333, df = 1, p = 0.068
De qiFeltDidn’t feelTotal
LI49 (14.1%)55 (85.9%)64
LI108 (12.5%)56 (87.5%)64
Total17111128
Pearson χ2 test: χ2 = 0.068, df = 1, p = 0.79

(H). Comparison of the trial nums when sham needles were performed.

Correct or incorrectFelt a realFelt a fakeTotal
1st181331
2nd181129
3rd141630
4th20828
Total7048118
Pearson χ2 test: χ2 = 3.803, df = 3, p = 0.28
Skin penetration sensationFeltDidn’t feelTotal
1st20 (62.5%)12 (37.5%)32
2nd21 (65.6%)11 (34.4%)32
3rd18 (56.3%)14 (43.7%)32
4th21 (65.6%)11 (34.4%)32
Total8048128
Pearson χ2 test: χ2 = 0.800, df = 3, p = 0.84
De qiFeltDidn’t feelTotal
1st4 (12.5%)28 (87.5%)32
2nd3 (9.4%)29 (90.6%)32
3rd6 (18.8%)26 (81.2%)32
4th4 (12.5%)28 (87.5%)32
Total17111128
Pearson χ2 test: χ2 = 1.3289, df = 3, p = 0.73

df = 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 de qi (Table 2C). The number of times that participants reported “Felt real” and “Maybe felt real”, and the number of times that participants reported “Felt fake” and “Maybe felt fake” have been shown (after excluding “Didn’t know”) for comparing the needle that was used for performing acupuncture. For the skin-penetration sensation and de qi, all corresponding data were analyzed. There was a significant difference between sham and real needles, and these were found to be non-independent (χ2 = 12.878, df = 1, p < 0.01). Therefore, the needling sensations from the sham and real needles were not equivalent. Moreover, the real and sham needles were indicated to be non-independent with regard to the skin-penetration sensation and de qi2 = 8.316, df = 1, p < 0.01 and χ2 = 16.686, df = 1, p < 0.01, respectively). The skin-penetration sensation was reported 80 times (62.5%) after the use of the sham needle, and this was close to the 101 times (78.9%) reported for the real needle. This value resembles the incorrect answer rate for the sham needle and the correct answer rate for the real needle (Table 2B), with a skin-penetration sensation observed in 88.8% of incorrect answers for the sham needle and in 96.0% of the correct answers for the real needle. Therefore, it was observed that the recognition of the skin-penetration sensations was more strongly involved in the identification of acupuncture stimulation than in the de qi.

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 de qi in men and women (Table 2D). The identification of the needle and skin-penetration sensation was shown to be non-independent when compared between sexes (χ2 = 4.753, df = 1, p < 0.05 and χ2 = 8.016, df = 1, p < 0.01).

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 de qi: χ2 = 10.687, df = 1; p < 0.01, χ2 = 8.016, df = 1, p < 0.01; and χ2 = 10.468, df = 1, p < 0.01, respectively). In women, however, real and sham needles were independent in terms of needle identification and the skin-penetration sensation (χ2 = 3.481, df = 1, p = 0.06 and χ2 = 1.781, df = 1, p = 0.18). These results suggest a sex difference in the needling sensation elicited by a sham needle, indicated by the fact that women reported that the sham needle-induced sensation was equivalent to that induced by a real needle.

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 de qi by sham needles at LI4 and LI10 (Table 2G). All outcomes showed independence in a comparison of LI4 and LI10 (χ2 = 2.045, df = 1, p = 0.15, χ2 = 3.333, df = 1, p = 0.06, and χ2 = 0.068, df = 1, p = 0.79). Therefore, there were no differences in forearm needling sensation induced by a sham needle.

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 de qi, in the 1st, 2nd, 3rd, and 4th needling sessions (Table 2H). All outcomes showed independence when stratified by trial number (identification, skin penetration sensation, and de qi, χ2 = 3.803, df = 3, p = 0.28, χ2 = 0.800, df = 3, p = 0.84 and χ2 = 1.3289, df = 3, p = 0.73, respectively). Therefore, no differences in sham needle-needling sensation were observed as a function of the trial number.

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 de qi, the skin-penetration sensation was more strongly involved in the blinding rate of the sham needle.

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.

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.
Journal of Acupuncture and Meridian Studies 2023; 16: 30-39https://doi.org/10.51507/j.jams.2023.16.1.30

Fig 2.

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).
Journal of Acupuncture and Meridian Studies 2023; 16: 30-39https://doi.org/10.51507/j.jams.2023.16.1.30

Table 1 . Baseline demographic and clinical characteristics for each group.

GroupReal needleSham 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/Female18/1417/1516/1615/1714/1815/1716/1617/15
Age (mean ± SD)21.8 ± 1.521.8 ± 1.421.7 ± 1.421.8 ± 1.221.7 ± 1.421.7 ± 1.521.7 ± 1.421.7 ± 1.6

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 realMaybe felt a realDidn’t knowMaybe felt a fakeFelt a fakeTotal
Real needle63 (49.2%)36 (28.1%)5 (3.9%)20 (15.6%)4 (3.1%)128
Sham needle18 (14.1%)52 (40.6%)10 (7.8%)32 (25.0%)16 (12.5%)128
Total8188155220256

(B). Correctly answered rate of real needle and incorrectly answered rate of sham needle.

CorrectIncorrectCorrectly answered (rate)
Real needle99 (Felt a real + Maybe)29 (Felt a fake + Maybe+ Didn’t know)99/128 (77.3%)
CorrectIncorrectIncorrectly answered (rate)
Sham needle48 (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 incorrectFelt a realFelt a fakeTotal
Real needle9924123
Sham needle7048118
Total16972241
Pearson χ2 test: χ2 = 12.878, df = 1, p < 0.001
Skin penetration sensationFeltDidn’t feelTotal
Real needle101 (78.9%)27 (21.1%)128
Sham needle80 (62.5%)48 (37.5%)128
Total18175256
Pearson χ2 test: χ2 = 8.316, df = 1, p = 0.0039
De qiFeltDidn’t feelTotal
Real needle45 (35.2%)83 (64.8%)128
Sham needle17 (13.3%)111 (86.7%)128
Total62194256
Pearson χ2 test: χ2 = 16.686, df = 1, p < 0.001

(D). Comparison of gender when sham needles were performed.

Correct or incorrectFelt a realFelt a fakeTotal
Male282957
Female421961
Total7048118
Pearson χ2 test: χ2 = 4.753, df = 1, p = 0.029
Skin penetration sensationFeltDidn’t feelTotal
Male31 (50.0%)31 (50.0%)62
Female49 (74.2%)17 (25.8%)66
Total8048128
Pearson χ2 test: χ2 = 8.016, df = 1, p = 0.0046
De qiFeltDidn’t feelTotal
Male6 (9.7%)56 (90.3%)62
Female11 (16.7%)55 (83.3%)66
Total17111128
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 incorrectFelt a realFelt a fakeTotal
Real needle491463
Sham needle282957
Total7743120
Pearson χ2 test: χ2 = 10.687, df = 1, p = 0.0011
Skin penetration sensationFeltDidn’t feelTotal
Real needle49 (74.2%)17 (25.8%)66
Sham needle31 (50.0%)31 (50.0%)62
Total8048128
Pearson χ2 test: χ2 = 8.016, df = 1, p = 0.0046
De qiFeltDidn’t feelTotal
Real needle22 (33.3%)44 (66.7%)66
Sham needle6 (9.7%)56 (90.3%)62
Total28100128
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 incorrectFelt a realFelt a fakeTotal
Real needle501060
Sham needle421961
Total9229121
Pearson χ2 test: χ2 = 3.481, df = 1, p = 0.062
Skin penetration sensationFeltDidn’t feelTotal
Real needle52 (83.9%)10 (16.1%)62
Sham needle49 (74.2%)17 (25.8%)66
Total10127128
Pearson χ2 test: χ2 = 1.781, df = 1, p = 0.18
De qiFeltDidn’t feelTotal
Real needle23 (37.1%)39 (62.9%)62
Sham needle11 (16.7%)55 (83.3%)66
Total3494128
Pearson χ2 test: χ2 = 6.840, df = 1, p = 0.0089

(G). Comparison of LI4 and LI10 when sham needles were performed.

Correct or incorrectFelt a realFelt a fakeTotal
LI4402161
LI10302757
Total7048118
Pearson χ2 test: χ2 = 2.045, df = 1, p = 0.15
Skin penetration sensationFeltDidn’t feelTotal
LI445 (70.3%)19 (29.7%)64
LI1035 (54.7%)29 (45.3%)64
Total8048128
Pearson χ2 test: χ2 = 3.333, df = 1, p = 0.068
De qiFeltDidn’t feelTotal
LI49 (14.1%)55 (85.9%)64
LI108 (12.5%)56 (87.5%)64
Total17111128
Pearson χ2 test: χ2 = 0.068, df = 1, p = 0.79

(H). Comparison of the trial nums when sham needles were performed.

Correct or incorrectFelt a realFelt a fakeTotal
1st181331
2nd181129
3rd141630
4th20828
Total7048118
Pearson χ2 test: χ2 = 3.803, df = 3, p = 0.28
Skin penetration sensationFeltDidn’t feelTotal
1st20 (62.5%)12 (37.5%)32
2nd21 (65.6%)11 (34.4%)32
3rd18 (56.3%)14 (43.7%)32
4th21 (65.6%)11 (34.4%)32
Total8048128
Pearson χ2 test: χ2 = 0.800, df = 3, p = 0.84
De qiFeltDidn’t feelTotal
1st4 (12.5%)28 (87.5%)32
2nd3 (9.4%)29 (90.6%)32
3rd6 (18.8%)26 (81.2%)32
4th4 (12.5%)28 (87.5%)32
Total17111128
Pearson χ2 test: χ2 = 1.3289, df = 3, p = 0.73

df = degrees of freedom..


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