A Randomized Controlled Trial Of
Placebo Acupuncture vs Real Acupuncture
Greg Goddard, DDS
Daniela Albers, DDS
Jaime Guachalla, DDS
Background Placebo acupuncture is difficult to perform because the patient can see and feel the depth of the needle. In addition, the placement of a needle in any position elicits a biological response that may complicate the interpretation of the studies.
Objective To determine if study participants can differentiate real acupuncture treatment from placebo acupuncture.
Design, Setting, and Patients Forty healthy volunteers (19 men and 21 women) from Universidad Mayor in Santiago, Chile, were randomly assigned to 1 of 2 groups: real acupuncture with a foam pad or placebo acupuncture with a foam pad using a blunted acupuncture needle that only touched the skin.
Intervention The acupuncture needle was blunted and went through a foam pad (that was stuck temporarily to the skin of the patient at Hegu point, LI 4). The needle was placed there for 15 minutes with stimulation (rotation) every 5 minutes.
Main Outcome Measure Volunteers answered a brief questionnaire indicating whether they thought they had received real or placebo acupuncture.
Results Twenty subjects received real acupuncture; 80% (16/20) correctly identified getting real acupuncture and 20% (4/20) believed they received placebo acupuncture instead. Twenty subjects received placebo acupuncture; 60% (12/20) correctly identified placebo acupuncture, and 40% (8/20) believed they had received real acupuncture instead. There was no significant difference between the type of acupuncture the participants received (real or placebo) and what they believed they received (x2 = 1.07; P.30).
Conclusion The placebo acupuncture method used in this study may be valid in future studies to establish a control (placebo) group.
Acupuncture, Placebo, Control Group, Blunted Needle, Randomized Controlled Trial
In 1997, the National Institutes of Health (NIH), in a consensus development statement, provided an assessment of the use and effectiveness of acupuncture for a variety of conditions such as postoperative dental pain, myofascial pain, and headache. In addition, it was established that acupuncture is an effective complementary and alternative medicine.1
Studies have shown the use of acupuncture to be effective for the treatment of many disorders and illnesses such as temporomandibular disorders,1-3 muscle pain, chronic pain, and headache.1-4 In a short-term pain-reduction study of acupuncture for chronic orofacial pain, Goddard et al2 found that acupuncture provided a significant short-term pain reduction in patients with chronic orofacial pain. In a meta-analysis of 14 randomized controlled trials of acupuncture for chronic pain, Patel et al5 found that most results favored acupuncture. Despite the number of positive findings, effectiveness of acupuncture is still questionable because of a lack of control groups in the studies.
Opioid peptides are released during acupuncture and it is claimed that this could be the explanation for the analgesic affects of acupuncture.1 Cho et al6 used functional magnetic resonance imaging to investigate the effects of acupuncture in the central nervous system. They found that the anterior cingulate cortex and thalamic areas were activated because of pain stimulation, and a decrease of these areas was noted when acupuncture was performed. In addition, alteration of the secretion of neurotransmitters and neurohormones and changes in the regulation of blood flow, both centrally and peripherally, have been documented.1
Placebo acupuncture is difficult to perform because the patient can see and feel the depth of the needle. Lao et al7 described a placebo acupuncture technique in which the patient had his/her eyes covered and the placebo needle was taped on the hand and connected to a wire with a flashing light. With this technique, subjects were not able to distinguish between real and placebo acupuncture, but this method seemed too complicated. Other studies tend to use sham acupuncture (acupuncture in areas not recognized as acupuncture points2) as a control group, but Goddard et al2 found that reduction of pain due to a noxious stimulus (i.e., needling) might not be specific to the location of the stimulus. In addition, the placement of a needle in any position elicits a biological response that may complicate the interpretation of the studies. Sham acupuncture seemed to produce some of the same biological efects that are produced by acupuncture.1
The purpose of this study was to determine if subjects could differentiate a simple placebo acupuncture technique from a real acupuncture treatment. During this treatment, the acupuncture needle only pricked the skin without penetrating it. For this, the needle was blunted and went through a foam pad (that was stuck temporarily to the skin of the patient at Hegu point); this foam pad helped to hold the needle and gave no chance for the patient to see the penetration of the needle and realize which method was used (real or placebo acupuncture).
The hypothesis was that subjects would not be able to discriminate between the real acupuncture and the placebo method, validating it for future use as an accurate control.
MATERIALS AND METHODS
Forty volunteers, 21 men and 19 women, were recruited from students at the Universidad Mayor, Santiago, Chile, to participate in this study. Inclusion criteria included age of at least 18 years and never having had experienced acupuncture. Exclusion criteria were pregnancy, the presence of coagulopathies or vascular diseases, and being needle-phobic.
Figure 1. Foam pad over LI 4 used in placebo vs real acupuncture trial
Figure 2. Needle in place at LI 4
Figure 3. Acupuncture needle and guide tube
A random table was created to organize subjects into 1 of 2 groups, real acupuncture treatment (n=20) or placebo treatment (n=20). We used the "randomly group table"8 approach to generate the random table.
Most studies are usually double-blinded but in acupuncture studies, this is difficult to achieve because it is impossible to blind the acupuncturist. Therefore, this study was single-blinded (the subjects were unaware of treatment assignment).
Seirin acupuncture needles J type (3 gauge x 30 mm length) were used. To blunt the needles (10 mm from original needle length), a sterile wire cutter was used. Self-adhesive foam 10-mm thick was cut into 20 x 20-mm squares.
Subjects signed a consent form approved by Universidad Mayor. The consent form described what the procedure was about and the possible risks and discomforts participants could expect when receiving acupuncture.
This study took 4 weeks to complete. During these 4 weeks, the volunteers who participated in this study were scheduled individually for appointments of 20 minutes. The 40 volunteers were randomly assigned to 1 of 2 groups. Neither group was told a description of acupuncture or if they were going to receive real or placebo acupuncture.
The 1st group received real acupuncture at Hegu point (LI 4) for 15 minutes with needle stimulation (10 clockwise and counterclockwise rotations) every 5 minutes. The 2nd group received placebo acupuncture at Hegu point (LI 4) for 15 minutes; in this group, the needles were blunted and did not penetrate the skin but only touched it. In both groups at Hegu point, a foam pad was stuck temporarily to the skin so the needle went through it, before touching (placebo acupuncture) or penetrating (real acupuncture) the skin.
The acupuncturist who treated both groups was a dental student from Universidad Mayor (who had taken the University of California, San Francisco, and Universidad Mayor acupuncture courses), and was instructed in the technique by a state-certified dental acupuncturist.
At each appointment, the volunteers were seated on a dental chair with their right arm resting on a side table. The skin zone of Hegu point was cleaned with alcohol pads, air-dried, and then covered with the foam pad (20 x 20 x 10 mm), with the sticky side toward the skin (Figure 1). The acupuncture needle, in a clear guide tube, was then inserted by tapping and twisting it slightly through the foam pad.
If the volunteer was assigned to receive real acupuncture, a sterile needle went through the foam pad at Hegu point to a depth of 10-20 mm into the skin (Figure 2). The needle was placed there for 15 minutes with stimulation (rotation) every 5 minutes.
Subjects who were assigned to the placebo group had a sterile shortened blunt needle (Figure 3) that went through the foam pad (previously stuck to the skin) until it touched the skin with no penetration. This was done by subtracting the thickness of the foam pad plus the portion of the needle that was cut when blunted. The needle stayed in place for 15 minutes and had stimulation (rotation) every 5 minutes.
After 15 minutes of either real or placebo acupuncture, the needle and the foam pad were removed. The skin was cleaned with an alcohol pad. After treatment, the acupuncturist asked the subjects a single question: "Do you believe you received real or placebo acupuncture?" At this time, the subjects were alone and when the questionnaire was completed, the acupuncturist took the form and escorted the subject out.
All 40 volunteers answered the form and followed the procedure correctly; therefore, all the data were considered credible. The placebo acupuncture group had a 10:10 male-to-female ratio, and the average age was 22.7 years old. The real acupuncture group had a 9:11 male-to-female ratio, and the average age was 22.4 years old.
Twenty subjects received real acupuncture; 80% (16/20) correctly identified getting real acupuncture, and 20% (4/20) believed they received placebo acupuncture instead.
Twenty subjects received placebo acupuncture; 60% (12/20) correctly identified placebo acupuncture, and 40% (8/20) believed they had received real acupuncture instead.
A t test was performed to determine if there were any significant age differences between the 2 groups. A P value of <=.05 was considered statistically significant; the calculated P value was .85 (i.e., no significant difference in age between groups).
The x2 test result of 1.071 indicated that there was no significant difference between the types of acupuncture the subjects received (real or placebo) compared with what they believed they had received (P<=.30). Overall, 70% (28/40) of the subjects believed they received real acupuncture, and 30% (12/40) believed they received placebo acupuncture.
The ideal standard experimental setup would have been to use a double-blind placebo-controlled clinical trial (impossible because the acupuncturist must be aware of what acupuncture method to use, real or placebo). Thus, this study used a single-blind method.
The acupuncturist practiced the insertion of the needle for both placebo and real treatment at least 40 times prior to the initiation of the study. Hegu point, located at the highest point of the adductor pollicis muscle with the thumb and index finger adducted,1 was chosen because it is considered to be a common and powerful acupoint for head and neck pain, and it is considered the most important analgesic point.9 In addition, Yang et al10 found in a neuromagnetic study that when the Hegu point was stimulated, the activation of the jaw and face projection areas of the brain was achieved, showing why Hegu point should be effectively used in the treatment of head and neck pain.
To keep the same standards for every subject, the same room and dental chair were used for all participants. The only interaction they had with the acupuncturist was the explanation of what they were going to receive (acupuncture at Hegu Point and afterward, answer a questionnaire); no questions were answered about the study to the subjects. Moreover, to ensure that the subjects did not communicate what the study was about, they were supervised upon leaving the room and asked not to talk about what happened inside the treatment room. To avoid possible bias of technique discrepancy by the participants, subjects who had never experienced acupuncture were selected.
There was no significant difference between the 2 treatments and there was no difference in the pool of subjects between each group, making it credible to compare the results. The method proposed as the control group in this study is valid to be used in future studies as a noninvasive control group. In this study, the majority (70%) of the subjects believed they received real acupuncture; this is because the method used as control resembled closely the real treatment. Also, 40% from the control group believed they received real acupuncture, validating that subjects were not able to differentiate between the real acupuncture method and the control one.
The placebo method used in this study closely resembled the real method of acupuncture; this might be the main reason why subjects were not able to differentiate between the 2 treatments. For this study, all subjects could witness the insertion of the needle. They could feel a prick on the skin that resembled the penetration of the needle. Subjects could not differentiate whether the needle was blunted because it was kept inside the guide tube, the rotation of the needle in the placebo group bore a close resemblance to real acupuncture, and after the removal of the foam pad, subjects saw the imprint left by the needle in the skin. All these reasons could explain why many in the control group believed they had received real acupuncture.
Twenty percent of subjects who received real acupuncture believed they had received placebo acupuncture. This could have many explanations: perhaps the subjects never felt the prick of either the needle or its penetration through the skin; also, they may not have recognized their Qi sensation since subjects were acupuncture-naive. Also, as the placebo needle pricked the skin in an acupoint, there is a chance that the stimulation of the blunted needle could stimulate the same effects of real acupuncture, but it has been difficult to identify the physiological activity of placebo needle at the acupoint.9
This study repeats and validates a previous study by Goddard et al11 that showed this type of placebo acupuncture was indistinguishable from real acupuncture.
The primary limitation of this study was the control method used and that only acupuncture-naive subjects could participate. Nevertheless, this method is still valid for use in future studies as a control (placebo). Further studies should be done to investigate the effects of the needle prick on the skin and to validate the use of this method in other acupoints.
The placebo acupuncture method used in this study may be valid for future studies as a control (placebo) in acupuncture-naive subjects.
We would like to thank Dr Benjamin Martinez for his special help in the statistical analysis, and dental school students of Universidad Mayor, Santiago, Chile, for their volunteer participation.
- Acupuncture: NIH Consensus Statement. JAMA. 1998;280(17):1518-1524.
- Goddard G, Karibe H, McNeill C, Villafuerte E. Acupuncture and sham acupuncture reduce muscle pain in myofascial pain patients. J Orofac Pain. 2002;16(1):71-76.
- Rosted P. The use of acupuncture in dentistry: a review of the scientific validity of published papers. Oral Dis. 1998;4(2):100-104.
- Dowson DI, Lewith GT, Machin D. The effects of acupuncture versus placebo in treatment of headache. Pain. 1985;21:35-42.
- Patel M, Gutzwiller F, Paccaud F, Marazzi A. A meta-analysis of acupuncture for chronic pain. Int J Epidemiol. 1989;18(4):900-906.
- Cho ZH, Son Y, Han JY, et al. fMRI neurophysiological evidence of acupuncture mechanisms. Medical Acupuncture. 2001;14(1):11-22.
- Lao L, Bergman S, Hamilton GR, et al. Evaluation of acupuncture for pain control after oral surgery: a placebo-controlled trial. Arch Otolaryngol Head Neck Surg. 1999;125(5):567-572.
- Snedecor G, Cochran W. Statistical Methods: Séptima Edición. Ames: Iowa State University Press; 1980:463-471.
- Vase L, Riley JL 3rd, Price DD. A comparison of placebo effects in clinical analgesic trials versus studies of placebo analgesia. Pain. 2002;99(3): 443-452.
- Yang ZL, Ouyang Z, Cheng YG, Chen YX. A neuromagnetic study of acupuncturing LI-4 (Hegu). Acupunct Electrother Res. 1995;20(1):15-20.
- Goddard G, Shen Y, Steele B, Springer N. A controlled trial of placebo versus real acupuncture. J Pain. 2005;6(4):237-242.
Dr Greg Goddard is an Orofacial Pain Specialist, specializing in the evaluation and conservative treatment of orofacial pain problems, including disorders of the temporomandibular joint and associated muscles. His research interests include acupuncture in the treatment of orofacial pain. Dr Goddard is Associate Clinical Professor in the Department of Oral and Maxillofacial Surgery at the University of California, San Francisco.
Greg Goddard, DDS, PhD*
University of California at San Francisco
707 Parnassus Ave, Rm D-1050
San Francisco, CA 94143-0768
Dr Daniela Albers practices acupuncture in her dentistry practice, and teaches Acupuncture, Occlusion, and Statistics at Mayor University in Santiago, Chile.
Daniela Albers, DDS
56-2-215 25 09
Fray Martin 12598
Santiago, Chile 759-0951
Dr Jaime Guachalla practices acupuncture in her dentistry practice, teaches Oral Rehabilitation and Occlusion at Universidad Mayor in Santiago, Chile, and has conducted research studies of acupuncture for dentistry.
Jaime Guachilla, DDS
*Correspondence and reprint requests