|Most randomised-controlled trials of acupuncture use penetrating sham acupuncture as control intervention. Sham acupuncture is described as acupuncture at points which are not known as acupuncture points. Because of physiological changes due to skin penetration sham acupuncture should not be defined as placebo control. In 1998 a new placebo needle was introduced by Streitberger. This placebo needle allows patient-blinding without penetration of the skin. Since then, this placebo needle and similar devices were used frequently as non-penetrating sham acupuncture in validation studies, experimental studies and randomised controlled trials. |
This brief review will introduce the Streitberger placebo needle, the Park sham device and a simple blunt needle technique. Since 1999 more than 40 randomized controlled trials (RCT) used one of these non penetrating devices. Significant better improvement in acupuncture compared to control was shown mainly in some pain conditions. However, many studies could not show a statistical significant difference between the two groups. Reasons might include a different power of placebo effects according to the condition treated, minimal effects by touching the skin with the sham needle and the fact that many studies were pilot studies with small sample sizes.
Due to the heterogeneity of these studies a conclusive statement about the clinical effects of acupuncture is not possible yet.
Especially in pain conditions further studies of acupuncture compared to non-penetrating sham acupuncture are necessary to lead to a better understanding of the importance of needle insertion. A critical discussion might allow to detect problems in existing studies and to improve protocols for further studies.
|A major problem in acupuncture research is the lack of adequate control groups (1).|
Most randomised-controlled trials of acupuncture use penetrating sham acupuncture as control intervention. Sham acupuncture is described as acupuncture at points which are not known as acupuncture points. Because of physiological changes due to skin penetration sham acupuncture should not be defined as placebo control.
An optimal placebo device for acupuncture should be performed in the same therapeutic setting as real acupuncture. Patients should not be able to distinguish the placebo therapy from real acupuncture therapy, they should feel needle penetration, the same acupoints should be used and the skin should not be penetrated in order to avoid physiological effects (2).
|The placebo needle|
|In 1998 a new placebo needle was introduced by Streitberger (3). This placebo needle allows patient-blinding without penetration of the skin. A blunt tip causes a small pricking sensation when it touches the skin, simulating the puncture of skin. The needle is not firmly attached inside the handle in order to allow a shortening of the needle. Patients "see" the needle moving into their body. For fixation of the needle a plastic ring is covered by a plaster (fig.1). In real acupuncture the same procedure is used and after puncturing the plaster the sharp tip of the needle is inserted into deeper tissue layers.|
Before using the placebo needle in a clinical trial it was tested in a cross-over experiment with 60 healthy volunteers whether a needling with the placebo-needle is as credible as with a real acupuncture needle.
After randomisation the volunteers were needled in a cross-over design with a real acupuncture needle and with the placebo-needle at acupoint „Large Intestine 4“. The volunteers were asked if they felt the needle penetration through the skin, how painful the penetration of the needle was (on a Visual Analogue Scale = VAS), and if they felt a dull pain (DEQI-feeling). Baseline data and results are shown in table 1.
Concerning the comparative feeling of needle penetration 43 of 60 volunteers (72%, 95%-confidence interval: 59%; 83%) felt no difference. 12 volunteers felt penetration only with acupuncture (20%), 5 only with placebo (8%). As most important none of the volunteers suspected that the skin had not been punctured in one of both procedures. Therefore in this experiment the placebo-needle proved to be sufficiently credible to be used as a placebo in single blind conditions.
Since then, this placebo needle and similar devices were used frequently as non-penetrating sham acupuncture in validation studies, experimental studies and randomised controlled trials (4).
|The Park sham device and other techniques|
|Shortly after the description of the Streitberger needle a similar device with the same principle of a blunt telescopic needle but using a different applicator was introduced and evaluated by Park (Fig 2) (5, 6). Also studies with more simple concepts like sticking a blunt needle into a foam applicator were described (7, 8).|
|Randomized controlled trials|
|Acupuncture studies using non-penetrating sham acupuncture as control were identified by a systematic search covering the period from 1998 onwards in MEDLINE. Database searches were supplemented by screening of reference lists of systematic reviews and eligible primary studies. Participant blinded randomized controlled trials (RCT) were described qualitatively in tables. Yet, the methodological quality of the studies was not analysed in detail. |
Since 1999 at least 40 RCT used one of those non penetrating devices (table 2). Significant better improvement in acupuncture compared to control was shown 15 trials, mainly in some pain conditions. However, 25 studies could not show a statistical significant difference between both groups in the main outcome criterion. Using multiple testing in 11 of these studies at least in one secondary criterion a significant better result for acupuncture could be detected.
From 20 studies including more than 50 patients only 6 showed a clearly significant effect in the main outcome criteria (Table 3). Only 2 of 8 studies which included more than 100 patients proved a significant effect.
|Due to the heterogeneity of the studies a conclusive statement about the clinical effects of acupuncture is not possible yet. |
Reasons for the inconclusive results might include a different power of placebo effects according to the condition treated, minimal effects by touching the skin with the sham needle and the fact that many studies were pilot studies without a clear definition of a main outcome criterion.
Especially in pain conditions further studies of acupuncture compared to non-penetrating sham acupuncture are warranted to lead to a better understanding of the importance of needle insertion. A critical discussion might allow to detect problems in existing studies and to improve protocols for further studies.
Double blinding remains a problem. Recently a device for double blinding acupuncture trials was introduced. The evaluation of the device seems to be promising to keep patient and acupuncturist blinded. However, as a matter of fact the quality of verum acupuncture depends on the experience and skill of the acupuncturist. In case of a negative result it could be argued that the acupuncture treatment was not appropriate. Furthermore using the double blinding device control of adverse effects like nerve injury or hematoma might be a problem.
Another concern in placebo acupuncture might be that even touching the skin might have physiologic effects. The physiologic activity of placebos is difficult or impossible to assess empirically and is normally determined on theoretical grounds (9, 10). Despite much experimental work on the physiological mechanisms of acupuncture, it is not known which aspects of the acupuncture treatment, such as the mode of stimulation or location of the acupuncture point, are specific to produce these physiological effects (11). If placebo needles are applied at acupuncture points, it is possible that manual stimulation by the blunted tip of the placebo needle may lead to acupuncture-like effects. It seems preferable therefore to apply the placebo needle away from acupuncture points. The sensations of pricking or pressure, which are important to convince the patient that they are receiving a credible treatment, will at least have no physiologic impact specific to acupuncture points (12).
Further empirical research is necessary on both the psychological and physiological effects of non-penetrating sham acupuncture techniques.
|1.Vincent, C., and Lewith, G. 1995. Placebo controls for acupuncture studies. J R Soc Med 88:199-202.|
2.Bing, Z., Villanueva, L., and Le Bars, D. 1990. Acupuncture and diffuse noxious inhibitory controls: naloxone-reversible depression of activities of trigeminal convergent neurons. Neuroscience 37:809-818.
3.Streitberger, K., and Kleinhenz, J. 1998. Introducing a placebo needle into acupuncture research. Lancet 352:364-365.
4.Ernst, E. 2006. Acupuncture--a critical analysis. J Intern Med 259:125-137.
5.Park, J., White, A., and Lee, H. 1999. Development of a new sham needle. Acupunct Med 17:110-112.
6.Park, J., White, A., Stevinson, C., Ernst, E., and James, M. 2002. Validating a new non-penetrating sham acupuncture device: two randomised controlled trials. Acupunct Med 20:168-174.
7.Goddard, G., Shen, Y., Steele, B., and Springer, N. 2005. A controlled trial of placebo versus real acupuncture. J Pain 6:237-242.
8.Karst, M., Rollnik, J.D., Fink, M., Reinhard, M., and Piepenbrock, S. 2000. Pressure pain threshold and needle acupuncture in chronic tension-type headache--a double-blind placebo-controlled study. Pain 88:199-203.
9.Gotzsche, P.C. 1994. Is there logic in the placebo? Lancet 344:925-926.
10.Vase, L., Riley, J.L., 3rd, and Price, D.D. 2002. A comparison of placebo effects in clinical analgesic trials versus studies of placebo analgesia. Pain 99:443-452.
11.Carlsson, C. 2002. Acupuncture mechanisms for clinically relevant long-term effects--reconsideration and a hypothesis. Acupunct Med 20:82-99.
12.Streitberger, K., and Vickers, A. 2004. Placebo in acupuncture trials. Pain 109:195; author reply 197-199.
13.Smith, M.J., and Tong, H.C. 2005. Manual acupuncture for analgesia during electromyography: a pilot study. Arch Phys Med Rehabil 86:1741-1744.
14.Kleinhenz, J., Streitberger, K., Windeler, J., Gussbacher, A., Mavridis, G., and Martin, E. 1999. Randomised clinical trial comparing the effects of acupuncture and a newly designed placebo needle in rotator cuff tendinitis. Pain 83:235-241.
15.Knight, B., Mudge, C., Openshaw, S., White, A., and Hart, A. 2001. Effect of acupuncture on nausea of pregnancy: a randomized, controlled trial. Obstet Gynecol 97:184-188.
16.David, J., Townsend, S., Sathanathan, R., Kriss, S., and Dore, C.J. 1999. The effect of acupuncture on patients with rheumatoid arthritis: a randomized, placebo-controlled cross-over study. Rheumatology (Oxford) 38:864-869.
17.Huguenin, L., Brukner, P.D., McCrory, P., Smith, P., Wajswelner, H., and Bennell, K. 2005. Effect of dry needling of gluteal muscles on straight leg raise: a randomised, placebo controlled, double blind trial. Br J Sports Med 39:84-90.
18.Sim, C.K., Xu, P.C., Pua, H.L., Zhang, G., and Lee, T.L. 2002. Effects of electroacupuncture on intraoperative and postoperative analgesic requirement. Acupunct Med 20:56-65.
19.Karst, M., Winterhalter, M., Munte, S., Francki, B., Hondronikos, A., Eckardt, A., Hoy, L., Buhck, H., Bernateck, M., and Fink, M. 2007. Auricular acupuncture for dental anxiety: a randomized controlled trial. Anesth Analg 104:295-300.
20.Jubb, R.W., Tukmachi, E.S., Jones, P.W., Dempsey, E., Waterhouse, L., and Brailsford, S. 2008. A blinded randomised trial of acupuncture (manual and electroacupuncture) compared with a non-penetrating sham for the symptoms of osteoarthritis of the knee. Acupunct Med 26:69-78.
21.Karst, M., Reinhard, M., Thum, P., Wiese, B., Rollnik, J., and Fink, M. 2001. Needle acupuncture in tension-type headache: a randomized, placebo-controlled study. Cephalalgia 21:637-642.
22.Streitberger, K., Friedrich-Rust, M., Bardenheuer, H., Unnebrink, K., Windeler, J., Goldschmidt, H., and Egerer, G. 2003. Effect of acupuncture compared with placebo-acupuncture at P6 as additional antiemetic prophylaxis in high-dose chemotherapy and autologous peripheral blood stem cell transplantation: a randomized controlled single-blind trial. Clin Cancer Res 9:2538-2544.
23.Kennedy, S., Baxter, G.D., Kerr, D.P., Bradbury, I., Park, J., and McDonough, S.M. 2008. Acupuncture for acute non-specific low back pain: a pilot randomised non-penetrating sham controlled trial. Complement Ther Med 16:139-146.
24.Vas, J., Mendez, C., Perea-Milla, E., Vega, E., Panadero, M.D., Leon, J.M., Borge, M.A., Gaspar, O., Sanchez-Rodriguez, F., Aguilar, I., et al. 2004. Acupuncture as a complementary therapy to the pharmacological treatment of osteoarthritis of the knee: randomised controlled trial. Bmj 329:1216.
25.Elden, H., Fagevik-Olsen, M., Ostgaard, H.C., Stener-Victorin, E., and Hagberg, H. 2008. Acupuncture as an adjunct to standard treatment for pelvic girdle pain in pregnant women: randomised double-blinded controlled trial comparing acupuncture with non-penetrating sham acupuncture. Bjog 115:1655-1668.
26.Park, J., White, A.R., James, M.A., Hemsley, A.G., Johnson, P., Chambers, J., and Ernst, E. 2005. Acupuncture for subacute stroke rehabilitation: a Sham-controlled, subject- and assessor-blind, randomized trial. Arch Intern Med 165:2026-2031.
27.Goldman, R.H., Stason, W.B., Park, S.K., Kim, R., Schnyer, R.N., Davis, R.B., Legedza, A.T., and Kaptchuk, T.J. 2008. Acupuncture for treatment of persistent arm pain due to repetitive use: a randomized controlled clinical trial. Clin J Pain 24:211-218.
28.Facco, E., Liguori, A., Petti, F., Zanette, G., Coluzzi, F., De Nardin, M., and Mattia, C. 2008. Traditional acupuncture in migraine: a controlled, randomized study. Headache 48:398-407.
29.Guerra de Hoyos, J.A., Andres Martin Mdel, C., Bassas y Baena de Leon, E., Vigara Lopez, M., Molina Lopez, T., Verdugo Morilla, F.A., and Gonzalez Moreno, M.J. 2004. Randomised trial of long term effect of acupuncture for shoulder pain. Pain 112:289-298.
30.Streitberger, K., Diefenbacher, M., Bauer, A., Conradi, R., Bardenheuer, H., Martin, E., Schneider, A., and Unnebrink, K. 2004. Acupuncture compared to placebo-acupuncture for postoperative nausea and vomiting prophylaxis: a randomised placebo-controlled patient and observer blind trial. Anaesthesia 59:142-149.
31.Smith, C., Coyle, M., and Norman, R.J. 2006. Influence of acupuncture stimulation on pregnancy rates for women undergoing embryo transfer. Fertil Steril 85:1352-1358.
32.Foster, N.E., Thomas, E., Barlas, P., Hill, J.C., Young, J., Mason, E., and Hay, E.M. 2007. Acupuncture as an adjunct to exercise based physiotherapy for osteoarthritis of the knee: randomised controlled trial. Bmj 335:436.