Rapid Responses to:
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Rapid Responses: Rapid Responses published:
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A true placebo?
- George T Lewith, Peter White (3 February 2006)
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Pitfalls in estimating the potency of “true “ placebo effects
- Michal R. Pijak (6 February 2006)
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A plastic eagle feather is a placebo.
- Ted J Kaptchuk (6 February 2006)
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Sham device v inert pill
- Dina Ralt (6 February 2006)
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Case unproven?
- Peter Moran (7 February 2006)
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Re: A plastic eagle feather is a placebo.
- George T Lewith, Peter White (8 February 2006)
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Comment on 'sham device v inert pill: randomised controlled trial of two placebo treatments1
- Stephen J Birch (9 February 2006)
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interesting!
- Jane Woo, MD, MPH (17 February 2006)
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Searching for an acupuncture placebo
- Noah Samuels, Shepherd R. Singer, Menachem Oberbaum (24 February 2006)
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Let's get real: a placebo is a placebo is a placebo
- Catherine E. Kerr (2 March 2006)
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Yes, let's get real: what placebo isn't
- Stephen Birch (10 March 2006)
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George T Lewith, Reader in Complementary Medicine University of Southampton, Peter White
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Kaptchuk et al’s article provides a fascinating insight into both acupuncture and placebos. There is no doubt about the emerging evidence demonstrating that acupuncture may have some specific treatment efficacy in knee pain1, neck pain2 and back pain3. Kaptchuk et al provided a placebo tablet but there is considerable doubt as to whether the Streitberger needle is a true placebo. This assertion has never been unequivocally proven yet underpins the forceful conclusions in this paper. No-one has yet defined a true acupuncture placebo satisfactorily. We demonstrated a difference in imaging patterns between Streitberger (placebo) and real acupuncture4 but this could simply have been a difference related to depth of needle insertion. The Streitberger needle touches the skin, feels like a needle and elicits similar needling sensations to real acupuncture4;5. Needling sensation is thought by some acupuncturists to define real acupuncture treatment, both clinically and mechanistically6. Furthermore, this placebo involves very similar techniques to approaches within Japanese acupuncture. The clinical evidence would suggest there is a difference in effect size between Streitberger and real acupuncture7, but it may just be that Kaptchuk’s placebo is a less effective form of acupuncture that is practised in Japan. If real acupuncture with deep needling penetration is more effective than touching the skin with a needle and eliciting needling sensation then this paper simply compares placebo amitriptyline with a relatively ineffective form of acupuncture. The incremental response to the “placebo needle” would be entirely consistent with this explanation as one would predict incremental symptom improvement from repeated acupuncture8. A further possible explanation may be that all acupuncture is placebo. Deeper needle penetration, associated with slightly increased pain and more intense needling sensation, may just be a more effective placebo than superficial penetration. There is little doubt that increasing evidence is emerging which indicates that the context in which a treatment is delivered may be of great importance9. If this is indeed the case, then the major effects which we observe within clinical trials of both acupuncture and conventional medicine may be more related to the context and environment of the trial than with the specific efficacy of the treatment being studied6;9. Reference List 1. Berman BM, Lao L, Langenberg P, Lee WL, Gilpin AMK, Hochberg MC. Effectiveness of acupuncture as adjunctive therapy in osteoarthritis of the knee. Annals of Internal Medicine 2004;141:901-10. 2. White P, Lewith GT, Prescott P, Conway J. Acupuncture versus placebo for the treatment of chronic mechanical neck pain. A randomised, controlled trial. Annals of Internal Medicine 2004;141:911-20. 3. Manheimer MS, White A, Berman B, Forys K, Ernst E. Meta-Analysis: Acupuncture for low back pain. Annals of Internal Medicine 2005;142:651- 63. 4. Pariente J, White P, Frackowiak RSJ, Lewith GT. Expectancy and belief modulate the neuronal substrates of pain treated by acupuncture. NeuroImage 2005;25:1161-7. 5. White P, Lewith GT, Hopwood V, Prescott P. The placebo needle, is it a valid and convincing placebo for use in acupuncture trials? A randomised, single blind, cross-over trial. Pain 2003;106:401-9. 6. Lewith GT, White P, and Kaptchuk T. Developing a research strategy for acupuncture. Clinical Journal of Pain . 2006. Ref Type: In Press 7. Streitberger K,.Kleinhenz J. Introducing a placebo needle into acupuncture research. Lancet 1998;352:364-5. 8. Ezzo J, Berman B, Hadhazy VA, Jadad AR, Lao L, Singh BB. Is acupuncture effective for the treatment of chronic pain? A systematic review. Pain 2000;86:217-25. 9. Paterson C,.Dieppe P. Characteristic and incidental (placebo) effects in complex interventions such as acupuncture. BMJ 2005;330:1202-5. Competing interests: None declared |
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Michal R. Pijak, assistant professor of medicine Slovak Medical University, Limbova 12, SK-83303 Bratislava, Slovak Republic
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EDITOR I have two critical comments regarding the study by Kaptchuk, et al.(1) First, it is unclear why the authors believe that “…comparison of two different placebos has the advantage of being less susceptible to bias than an unblinded waiting list control group “. Such reasoning is questionable and cannot outweigh the fact, that, without an additional untreated control group, the “true “ placebo effect cannot be distinguished from the overall placebo effects. For information, the true placebo effect is the difference between the overall placebo effects and the magnitude of the “time effect“ (other non-specific effects ) detected on untreated patients.(2) Second, the study results cannot support the author's assertion that a placebo effect exists over time because the average weekly changes in both the shame device group and the placebo group (-0,33 and 0,15, respectively), are unlikely to be clinically important. Indeed, the minimum clinically significant difference in pain on the 10 point numerical rating scale should be 1.3 (95% CI = 1.0 to 1.5).(3) Furthermore, the use of parametric statistical methods may increase the risk of a false positive result if the distribution of data deviates greatly from a normal distribution. Nevertheless, clinical experiences and data from previous studies revealed that procedures intimately involving the patient are associated with more powerful and long lasting placebo effects than an inert pill.(2) In closing one key point warrants emphasis. Randomised placebo controlled trials do not measure the true placebo effect observed in clinical praxis due to marked reduction of patients' expectations for improvement, also referred to as “response expectancies.” Ignoring this fact has already resulted in erroneous conclusions questioning the existence of the true placebo effect in clinical settings.(4) Hence, it seems that the use of deception might be necessary to understanding the “true “ placebo effect, but so far has received little systematic ethical attention.(5) References 1. Kaptchuk TJ, Stason WB, Davis RB, Legedza AR, Schnyer RN, Kerr CE, et al. Sham device v inert pill: randomised controlled trial of two placebo treatments. BMJ 2006 Feb 1; [Epub ahead of print] 2. Ernst E, Resch KL. Concept of true and perceived placebo effects. BMJ 1995;311:551-3. 3. Bijur PE, Latimer CT, Gallagher EJ. Validation of a verbally administered numerical rating scale of acute pain for use in the emergency department. Acad Emerg Med 2003;10:390-2. 4. Hrobjartsson A, Gotzsche PC. Is the placebo powerless? An analysis of clinical trials comparing placebo with no treatment. N Engl J Med 2001;344: 1594-602. 5. Miller FG, Wendler D, Swartzman LC. Deception in research on the placebo effect. PLoS Med 2005;2:e262. Epub 2005 Sep 6. Competing interests: None declared |
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Ted J Kaptchuk, professor Boston, MA 02215
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I appreciate the challenges raised by Lewith and White. Our trial’s goal was to compare to two different rituals: a device (sham acupuncture) and an oral placebo. Our team could have chosen to compare a sham plastic eagle feather and oral pill. If we obtained similar data, as our published study – i.e., device (feather) > pill, we suspect that some shamans would say that sham feathers were really, after all, an active treatment. Of course, the plastic feather could be an active intervention, but more likely the outcome of the plastic feather intervention was a placebo effect. We would have rejected the shaman’s argument as lacking parsimony or reasonableness. The Streitberger sham needle gently scratches the skin. It has been validated and used in clinical trials. As an acupuncturist, I do not believe that scratching the skin for chronic pain is acupuncture or a plausible active physiological treatment beyond a ritual. The evidence cited by Lewith and White is unpersuasive or totally not applicable. It would be helpful if acupuncturists stopped arguing that every time a placebo treatment is identical to active acupuncture in a trial, the placebo treatment, really, after all, was an active acupuncture treatment. If there is no placebo control possible for acupuncture experiments than it becomes impossible to ever falsify acupuncture claims and the proposition that acupuncture is more than placebo. Acupuncture should not hide behind the excuse that anything you do with a needle, including wave it, is a form of acupuncture. Our team stands by our forceful, parsimonious, reasonable and straightforward conclusions. Our trial is about placebo effects and not acupuncture. Introducing retrospective ad hoc explanations that serve to make it impossible to perform scientific experiments is not a helpful approach. (1) One can always find excuses; but science relies on evidence. Sincerely, Ted J Kaptchuk (1) Kaptchuk TJ. Effect of interpretive bias on research evidence. BMJ 2003; 326:1453-5. Competing interests: None declared |
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Dina Ralt, cellular biologist Tel Aviv, Israel 64352
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Kaptchuk et.al. compared sham device v inert pill but did not take into account the different conditions of the tested procedures. Sham effects were expected to differ because of the "touch" effect in only one of them. Indeed the acupuncture(-touch) had greater effect than the placebo pill. Recent studies point to the effect of nitric oxide in integrative therapies: "Intercellular communication, NO and the biology of Chinese medicine" Cell Commun Signal. 2005, 18, 3(1):8 http://www.biosignaling.com/content/3/1/8 Considering the NO gaseous and sensitive nature it is expected to be affected by various surrounding conditions and thus sham reactions with or without another person nearby can yield different results. Touch is expected to better the sham effect. Dina Ralt,PhD Izun & Tmura Izun.Tmura@gmail.com Competing interests: None declared |
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Peter Moran, Retired surgeon Ipswich Queensland
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Congratulations on an interesting study. However, is it not rather unusual for placebo-related phenomena to be delayed by some weeks, as appears to be the case only with the sham acupuncture? This leads to some questions. Were the patients somehow cued that the "business" part of the trial was being entered at the two week mark? That knowledge may have stimulated the more favourable reporting for the more intense, mysterious, and hands-on form of care, regardless of any true "effect" of the placebo. Also, was the extension of the trial only decided upon when the intended two week study failed to show the expected results? Competing interests: None declared |
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George T Lewith, Reader in Complementary Medicine University of Southampton, Peter White
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We note Kaptchuk’s response to our letter and wish to reiterate that we do not necessarily feel the Streitberger needle is definitely not a placebo. As Professor Kaptchuk suggested in his letter, we must rely on evidence and until we have hard evidence that proves the Streitberger needle is placebo, we cannot discount the fact that it may be active treatment. We must try to suspend our own opinion until there is evidence regarding efficacy of Japanese acupuncture which is widely practised. There are therefore a number of other possible explanations for the study. The first is that all acupuncture may be placebo with deeper and more painful needling being a more powerful placebo than superficial needling. An alternative explanation is that Streitberger is indistinguishable from some forms of acupuncture. We are not “irrational supporters” of acupuncture, simply seekers after the truth. At the moment we do not believe that we have adequately defined a true acupuncture placebo and therefore Kaptchuk’s experiment is open to various interpretations, all, potentially, equally correct. Competing interests: None declared |
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Stephen J Birch, Acupuncturist / researcher W.G. Plein 330, 1054 SG Amsterdam
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Comment on 'sham device v inert pill: randomised controlled trial of two placebo treatments1 The study by Kaptchuk and colleagues on placebo is intriguing, however some of its conclusions are not safe. Acupuncture is a complex intervention, due in part to the fact that the consultation and evolving discussions with the patient in acupuncture practice are a specific part of the treatment, intertwined with the specific needling components.2 Sham acupuncture studies accidentally lump these specific treatment context components with any placebo effects in the sham arm thus overstating the size of the placebo effects.2 Additionally, no inert sham acupuncture intervention has been developed yet, or if any are truly inert, none have been demonstrated to be so. The developers of the non-invasive sham needle device used in this study believed their sham was a 'placebo needle'.3 However, others writing about this agree that it is not inert and therefore cannot be considered as a placebo treatment because of the range of non-specific physiological effects that sham acupuncture can trigger,4 or that it may be ‘physiologically active’.5 Kaptchuk et al's study thus accidentally lumps any non-specific physiological effects together with placebo effects in the sham arm, again overstating the size of the placebo effects. That the study found a larger treatment effect in the second part of the study compared to the first in the sham acupuncture arms (ie an effect building up over time) is consistent with a different interpretation than the study investigators drew: the weak non-specific physiological and specific treatment context effects gradually accumulated over time. They were not apparent yet after the first period, but became measurable in the second. Since these effects were not thought about the study design could not control for or separate these effects from placebo effects. Thus it cannot disprove this interpretation of results. It is also highly likely, as Kaptchuk himself has argued elsewhere that these different treatment components interact and are inseparable.6 Under such circumstances it is not realistic to attempt to control for or measure placebo effects.2,6 The study highlights some of the peculiar difficulties of placebo research on acupuncture and not, as the authors conclude, that placebo effects "depend on the behaviours embedded in medical rituals."1 In short, the study investigators incorrectly assume that enhanced placebo effects in the sham acupuncture treatment arms triggered the observed changes, something they attribute to the 'ritual' of treatment. References 1) BMJ, doi:10.1136/bmj.38762.603310.55 (published 1 February 2006) 2) Paterson C, Dieppe P. Characteristic and incidental (placebo) effects in complex interventions such as acupuncture. BMJ, 2005;330:1202- 1205. 3) Streitberger K, Kleinhenz J. Introducing a placebo needle into acupuncture research. Lancet 1998;352:364-365. 4) Birch S, Hammerschlag R, Trinh K, Zaslawski C. The non-specific effects of acupuncture treatment: When and how to control for them. Clin Acup Orien Med 2002;3,1:20-25. 5) White AR. Acupuncture research methodology. In G Lewith, WB Jonas, H Walach. (eds). Clinical research in complementary therapies. Edinburgh, Churchill Livingstone, 2002; pp. 307-323. 6) Kaptchuk TJ, Edwards RA, Eisenberg DM. Complementary medicine: efficacy beyond the placebo effect. In Ernst E. (ed). Complemetary Medicine an objective appraisal. Oxford, Butterworth Heinmann, 1996, pp. 42-70. Stephen Birch PhD, LicAc (US), MBAcC (UK). Amsterdam, The Netherlands Competing interests: None declared |
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Jane Woo, MD, MPH, medical officer US Food & Drug Administration
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Thank you for sharing this very interesting finding. One of my residents once said that he advocated morphine injections, as opposed to tablets, because, "There's something about steel hitting skin and having a doctor say, 'This is going to make you feel better.' Injections simply work better than pills." You also confirm the well-known phenomenon that, yes, placebos (of all kinds) do have some effect. Competing interests: None declared |
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Noah Samuels, senior researcher Center for Integrated Complementary Medicine, Shaare Zedek Medical Center, Jerusalem, Israel, Shepherd R. Singer, Menachem Oberbaum
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EDITOR - In their research comparing placebo acupuncture to placebo pills, Kaptchuk et al.[1] use what is now called the “Streitberger needle” (SN) for their placebo acupuncture treatment. The SN differs from real acupuncture (RA) in that it applies pressure without penetrating the skin [2]. Though SN has been “verified” vis-à-vis RA, a cross-over pilot trial found that 39% of participants treated with both did feel a difference [3]. Another potential limitation with the use of SN is that while placebo treatments are supposed to be physiologically inert procedures, pressure exerted by SN may result in physiological effects similar to those produced by ice massage, heat or vibration [2]. And though the effects of SN differ from RA on brain PET scan readings, certain parameters are more similar between the two than for those receiving overt placebo treatment, with intermediate needling sensation scores with SN when compared with the other two interventions [4]. An alternative placebo technique was described in a study of patients suffering from pain following oral surgery. Empty plastic needle tubes (used by many acupuncturists to facilitate needle insertion) are placed over the bony area next to acupuncture points and lightly tapped to produce a discernible sensation. A real acupuncture needle is then attached adjacently with adhesive tape to the dermal surface [5]. Most participants felt that they were not receiving true treatment (3/20, as opposed to 11/19 with RA), though this was found to be due to a lack of response to treatment rather than to the procedure itself. Though this method does not result in physiological effects, it cannot be used in patients who have been treated in the past with RA. Other and less problematic methods for placebo acupuncture must be developed to evaluate the true efficacy (or lack thereof) of acupuncture treatment. Noah Samuels, senior researcher; Shepherd R. Singer, senior researcher; Menachem Oberbaum, department head; Center for Integrated Complementary Medicine, Shaare Zedek Medical Center, P.O.B. 3235, Jerusalem 91031, Israel. 1. Kaptchuk TJ, Stason WB, Davis RB, et al. Sham device v inert pill: randomized controlled trial of two placebo treatments. BMJ 2006; 332: 391- 97. 2. Streitberger K, Kleinhenz J. Introducing a placebo needle into acupuncture research. Lancet 1998; 352: 364-365. 3. White P, Lewith G, Hopwood V, Prescott P. The placebo needle, is it a valid and convincing placebo for use in acupuncture trials? A randomized, single-blind, cross-over pilot trial. Pain 2003; 106: 401-9. 4. Pariente J, White P, Frackowiak RSJ, Lewith G. Expectancy and belief modulate the neuronal substrates of pain treated by acupuncture. Neuroimage 2005; 25: 1161- 67. 5. Lao L, Bergman S, Hamilton GR, Langenberg P, Berman B. Evaluation of acupuncture for pain control after oral surgery. Arch Otolaryngol Head Neck Surg 1999; 125: 567- 72. Competing interests: None declared |
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Catherine E. Kerr, Researcher, Harvard Medical School Boston, MA USA 02215
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To the editor: Lewith, Birch and Samuels criticize the sham needle condition used in our study, suggesting the Streitberger needle we used to mimic the non- specific ritual aspects of real acupuncture treatment may in fact be a form of active acupuncture. This contention goes against the current evidence, one of the strongest forms of which, comes from the neuroimaging paper on which Lewith (1) is the senior author. That study compared the real and Streitberger needle effects on brain activations and found that real acupuncture activated the ipsilateral insula, an area related to interoceptive and visceroceptive processing (2), while the Streitberger needle device specifically activated the dorsolateral prefrontal cortex (DLPFC) a prefrontal region associated with both the placebo effect (3) and cognitive modulation of pain (4). The authors suggest their results provide a dissection between the real and ritual effects of acupuncture, with the real needle activating a limbic-viscerosensory pathway and the sham needle activating a cognitive pathway. They write that their data validate the idea that the Streitberger device "appears to mediate a potentially powerful non-specific clinical response to acupuncture." They further state, "we provide behavioral and physiological data that validate Streitberger Needle as a placebo control for acupuncture in clinical trials involving treatment of chronic pain." Given this neuroimaging data as well as experimental studies and clinical trials validating the Streitberger devvice (5) (6) (7) , the suggestion that the device is merely a less active form of acupuncture does not appear to be based on the evidence. Indeed, given the preponderance of data collected so far, the assertion that a device that sits on top of the skin and elicits a scratching sensation is really a form of active acupuncture may simply be unfalsifiable, a subject for metaphysical speculation rather than scientific investigation. References cited: 1. Pariente J , White P , Frackowiak RS , Lewith G . Expectancy and belief modulate the neuronal substrates of pain treated by acupuncture. Neuroimage. 2005 May 1: 25(4): 1161-7 2. Craig AD. How do you feel? Interoception: the sense of the physiological condition of the body. Nat Rev Neurosci. 2002 Aug; 3(8): 655 -66. 3. Wager TD, Rilling JK, Smith EE, Sokolik A, Casey KL, Davidson RJ, Kosslyn SM, Rose RM, and Cohen JD, Placebo-induced changes in FMRI in the anticipation and experience of pain, Science 303 (2004), pp. 1162–1167 4. Lorenz J, Minoshima S, Casey KL. Keeping pain out of mind: the role of the dorsolateral prefrontal cortex in pain modulation, Brain 126 (2003), pp. 1079–1091. 5. Streitberger K,.Kleinhenz J. Introducing a placebo needle into acupuncture research. Lancet 1998;352:364-5. 6. Kleinhenz J, Streitberger K, WIndeler J, Gussbacher A, Maridis G, Martin E. Randomised clinical trial comparing the effects of acupuncture and a newly designed placebo needle in rotator cuff tendinitis. Pain. 1999 Nov;83(2):235-41. 7. Fink M, Gutenbrunner C, Rollnik J, Karst M. Credibility of a newly designed placebo needle for clinical trials in acupuncture research. Forsch Komplementarmed Klass Naturheilkd 2001; 8: 368–72. Competing interests: None declared |
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Stephen Birch, acupuncturist & researcher Amsterdam 1054SG
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To the editor, This fascinating study tried to assess the effects of the ritual of treatment [1]. The ritual of what a therapist does most likely increases or decreases the placebo effect, it would be foolish to say otherwise. But it is just as likely that the way this ritual affects a patient is completely inseparable from the therapy that is delivered, hence it is probably impossible to separate the specific and non-specific components [2]. Further, recent evidence has shown that the nature of the interactions an acupuncturist has with a patient makes some of these interactions inherently part of the therapy, ie they contribute to the specific effects [3]. This makes it virtually impossible to separate these specific contextual effects from other non-specific contextual effects [2]. It also biases against acupuncture when we try using a sham acupuncture study since the sham arm will contain these non-placebo related contextual specific effects [3, 4]. Validation of the Streitberger sham needle does not mean that it is physiologically inert, only that people couldn’t tell if they were receiving sham or not. At the very least the sham contains non-specific effects due to touch which has demonstrated physiological effects [5, 6] and various pressure and mild stimulation components [7]. If not controlled for a non-inert sham produces bias in clinical trials. This is especially so if any of these physiological effects are specific to the condition being treated or if the therapy produces a relatively small treatment effect [4]. Just as one needs to control for time effects such as regression to the mean and natural course of the disease if one is attempting to compare and quantify placebo effects [8], so too these other effects must be controlled for. Kaptchuk et al’s placebo study [1] did not do this, thus it cannot draw conclusions about the ritual of treatment in relation to acupuncture therapy. In their rebuttals to letters about their study, Kerr and Kaptchuk’s opinions about placebo [9] and acupuncture [10] and appealing to the doctrine of falsifiability [10, 9,] do not change this fact. As a final comment on this study, it does not report results of the comparison of the sham and real acupuncture treatments. This may be a telling point. When a practitioner performs what they normally do, their performance is not acted, it is natural. When the same practitioner has to perform a sham imitation of what they normally do, they must act this performance so as to make it convincing to the patient. It is thus highly probable that the ‘ritual of treatment’ and any effects it may have in the sham and real acupuncture groups will differ. But just as the contributing effects of this ritual will be inseparable from the effects of the therapy itself, so too the effects of the ritual in the sham. In other words one cannot infer about the relative contribution of the ritual in the sham and real acupuncture treatments because of the difficulty separating out these effects and because they are probably uneven. So too, one cannot infer anything about the relative contribution of the ritual of acupuncture treatment in comparison to the placebo medication. This placebo study is methodologically inadequate to address the question for which it was designed. Such problems have and continue to plague acupuncture studies, which are methodologically very complex [11, 12]. References 1) Kaptchuk TJ, Stason WB, Davis RB, Legedza ART, Schnyer RN, Kerr CE, Stone DA, Nam BH, Kirsch I, Goldman RH. Sham device v inert pill: randomized controlled trial of two placebo treatments. BMJ 2006; 332:391- 397. 2) Kaptchuk TJ, Edwards RA, Eisenberg DM. Complementary medicine: efficacy beyond the placebo effect. In Ernst E. (ed). Complemetary Medicine an objective appraisal. Oxford, Butterworth Heinmann, 1996, pp. 42-70. 3) Paterson C, Dieppe P. Characteristic and incidental (placebo) effects in complex interventions such as acupuncture. BMJ, 2005;330:1202- 1205. 4) De Craen AJM, Tijssen JGM, Kleijnen J. Is there a need to control the placebo in placebo controlled trials? Heart, 1997, 77:95-96. 5) Field TM. Research on the effectiveness of massage. In Rakel DP, Faass N (eds). Complementary medicine in clinical practice. Boston, Jones and Bartlett Publishers, 2005, pp.259-266. 6) McCraty R, Atkinson M, Tomasino D, Tiller WA. The electricity of touch: Detection and measurement of cardiac energy exchange between people. In Pribram K (ed). Brain and Values: Is a Biological Science of Values Possible?, Mahwah, Lawrence Erlbaum Associates, Publishers, 1998, pp 359-379. 7) Birch S, Hammerschlag R, Trinh K, Zaslawski C. The non-specific effects of acupuncture treatment: When and how to control for them. Clin Acup Orien Med 2002;3,1:20-25. 8) Ernst E, Resch KL. Concept of true and perceived placebo effects. BMJ 1995, 311:551-553. 9) Kerr CE. Let’s get real: placebo is a placebo is a placebo. BMJ, March 2, 2006. 10) Kaptchuk TJ. A plastic eagle feather is placebo. BMJ, February 6, 2006. 11) Birch S. Clinical research of acupuncture: part two – controlled clinical trials an overview of their methods. J Alt Complem Med. 2004, 10, 3:481-498. 12) White AR, Filshie J, Cummings TM. Clinical trials of acupuncture: consensus recommendations for optimal treatment, sham controls and blinding. Complem Ther Med. 2001; 9:237-245. Stephen Birch PhD, LicAc (US), MBAcC (UK). Amsterdam, The Netherlands Competing interests: None declared |
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