Background Although acupuncture is widely used for chronic pain, there remains considerable controversy as to its value. We aimed to determine the effect size of acupuncture for 4 chronic pain conditions: back and neck pain, osteoarthritis, chronic headache, and shoulder pain.
Methods We conducted a systematic review to identify randomized controlled trials (RCTs) of acupuncture for chronic pain in which allocation concealment was determined unambiguously to be adequate. Individual patient data meta-analyses were conducted using data from 29 of 31 eligible RCTs, with a total of 17 922 patients analyzed.
Results In the primary analysis, including all eligible RCTs, acupuncture was superior to both sham and no-acupuncture control for each pain condition (P < .001 for all comparisons). After exclusion of an outlying set of RCTs that strongly favored acupuncture, the effect sizes were similar across pain conditions. Patients receiving acupuncture had less pain, with scores that were 0.23 (95% CI, 0.13-0.33), 0.16 (95% CI, 0.07-0.25), and 0.15 (95% CI, 0.07-0.24) SDs lower than sham controls for back and neck pain, osteoarthritis, and chronic headache, respectively; the effect sizes in comparison to no-acupuncture controls were 0.55 (95% CI, 0.51-0.58), 0.57 (95% CI, 0.50-0.64), and 0.42 (95% CI, 0.37-0.46) SDs. These results were robust to a variety of sensitivity analyses, including those related to publication bias.
Conclusions Acupuncture is effective for the treatment of chronic pain and is therefore a reasonable referral option. Significant differences between true and sham acupuncture indicate that acupuncture is more than a placebo. However, these differences are relatively modest, suggesting that factors in addition to the specific effects of needling are important contributors to the therapeutic effects of acupuncture.
Acupuncture is the insertion and stimulation of needles at specific points on the body to facilitate recovery of health. Although initially developed as part of traditional Chinese medicine, some contemporary acupuncturists, particularly those with medical qualifications, understand acupuncture in physiologic terms, without reference to premodern concepts.1
An estimated 3 million American adults receive acupuncture treatment each year,2 and chronic pain is the most common presentation.3 Acupuncture is known to have physiologic effects relevant to analgesia,4,5 but there is no accepted mechanism by which it could have persisting effects on chronic pain. This lack of biological plausibility, and its provenance in theories lying outside of biomedicine, makes acupuncture a highly controversial therapy.
A large number of randomized controlled trials (RCTs) of acupuncture for chronic pain have been conducted. Most have been of low methodologic quality, and, accordingly, meta-analyses based on these RCTs are of questionable interpretability and value.6 Herein, we present an individual patient data meta-analysis of RCTs of acupuncture for chronic pain, in which only high-quality RCTs were eligible for inclusion. Individual patient data meta-analysis are superior to the use of summary data in meta-analysis because they enhance data quality, enable different forms of outcome to be combined, and allow use of statistical techniques of increased precision.
The full protocol of the meta-analysis has been published.6 In brief, the study was conducted in 3 phases: identification of eligible RCTs; collection, checking, and harmonization of raw data; and individual patient data meta-analysis.
Data sources and searches
To identify articles, we searched MEDLINE, the Cochrane Collaboration Central Register of Controlled Trials, and the citation lists of systematic reviews (the full search strategy is shown in the eAppendix). There were no language restrictions. The initial search, current to November 2008, was used to identify studies for the individual patient data meta-analysis; a second search was conducted in December 2010 for summary data to use in a sensitivity analysis.
Two reviewers applied inclusion criteria for potentially eligible articles separately, with disagreements about study inclusion resolved by consensus. Randomized controlled trials were eligible for analysis if they included at least 1 group receiving acupuncture needling and 1 group receiving either sham (placebo) acupuncture or no-acupuncture control. The RCTs must have accrued patients with 1 of 4 indications—nonspecific back or neck pain, shoulder pain, chronic headache, or osteoarthritis—with the additional criterion that the current episode of pain must be of at least 4 weeks duration for musculoskeletal disorders. There was no restriction on the type of outcome measure, although we specified that the primary end point must be measured more than 4 weeks after the initial acupuncture treatment.
It has been demonstrated that unconcealed allocation is the most important source of bias in RCTs,7 and, as such, we included only those RCTs in which allocation concealment was determined unambiguously to be adequate (further details are in the review protocol6). Where necessary, we contacted authors for further information concerning the exact logistics of the randomization process. We excluded RCTs if there was any ambiguity about allocation concealment.
Data extraction and quality assessment
The principal investigators of eligible studies were contacted and asked to provide raw data from the RCT. To ensure data accuracy, all results reported in the RCT publication, including baseline characteristics and outcome data, were then replicated.
Reviewers assessed the quality of blinding for eligible RCTs with sham acupuncture control. The RCTs were graded as having a low likelihood of bias if either the adequacy of blinding was checked by direct questioning of patients (eg, by use of a credibility questionnaire) and no important differences were found between groups, or the blinding method (eg, the Streitberger and Kleinhenz sham device8) had previously been validated as able to maintain blinding. Randomized controlled trials with a high likelihood of bias from unblinding were excluded from the meta-analysis of acupuncture vs sham; a sensitivity analysis included only RCTs with a low risk of bias.
Data synthesis and analysis
Each RCT was reanalyzed by analysis of covariance with the standardized principal end point (scores divided by pooled standard deviation) as the dependent variable, and the baseline measure of the principal end point and variables used to stratify randomization as covariates. This approach has been shown to have the greatest statistical power for RCTs with baseline and follow-up measures.9,10 The effect size for acupuncture from each RCT was then entered into a meta-analysis using the metan command in Stata software (version 11; Stata Corp): the meta-analytic statistics were created by weighting each coefficient by the reciprocal of the variance, summing, and dividing by the sum of the weights. Meta-analyses were conducted separately for comparisons of acupuncture with sham and no-acupuncture control, and within each pain type. We prespecified that the hypothesis test would be based on the fixed effects analysis because this constitutes a valid test of the null hypothesis of no treatment effect.
We identified 82 RCTs (Figure 1),11-93 of which 31 were eligible (Table 1 and eAppendix). Four of the studies were organized as part of the German Acupuncture Trials (GERAC) initiative,11-14 4 were part of the Acupuncture Randomized Trials (ART) group15-18; 4 were Acupuncture in Routine Care (ARC) studies19-22; 3 were UK National Health Service acupuncture RCTs.23,24,98 Eleven studies were sham controlled, 10 had no-acupuncture control, and 10 were 3-armed studies, including both sham and no-acupuncture control. The second search for subsequently published studies identified an additional 4 eligible studies,94-97 with a total of 1619 patients.
An important source of clinical heterogeneity between studies concerns the control groups. In the sham RCTs, the type of sham included acupuncture needles inserted superficially,13 sham acupuncture devices with needles that retract into the handle rather than penetrate the skin,25 and nonneedle approaches, such as deactivated electrical stimulation26 or detuned laser.27 Moreover, cointerventions varied, with no additional treatment other than analgesics in some RCTs,15 whereas in other RCTs, both acupuncture and sham groups received a course of additional treatment, such as exercise led by physical therapists.24 Similarly, the no-acupuncture control groups varied among usual care, such as an RCT in which control group patients were merely advised to “avoid acupuncture”98; attention control, such as group education sessions28; and guidelined care, in which patients were given advice as to specific drugs and doses.13
Data extraction and quality assessment
Usable raw data were obtained from 29 of the 31 eligible RCTs, including a total of 17 922 patients from the United States, United Kingdom, Germany, Spain and Sweden. For 1 RCT, the study database had become corrupted29; in another case, the statisticians involved in the RCT failed to respond to repeated enquiries despite approval for data sharing being obtained from the principal investigator.30
The 29 RCTs comprised 18 comparisons with 14 597 patients of acupuncture with no-acupuncture group and 20 comparisons with 5230 patients of acupuncture and sham acupuncture. Patients in all RCTs had access to analgesics and other standard treatments for pain. Four sham RCTs were determined to have an intermediate likelihood of bias from unblinding13,27,31,32; the 16 remaining sham RCTs were graded as having a low risk of bias from unblinding. On average, dropout rates were low (weighted mean, 10%). Dropout rates were higher than 25% for only 4 RCTs: those by Molsberger et al30,97 (27% and 33%, respectively, but raw data were not received and neither RCT included in main analysis); Carlsson et al32 (46%, RCT excluded in a sensitivity analysis for blinding), and Berman et al28 (31%). This RCT had a high dropout rate among no-acupuncture controls (43%); dropout rates were close to 25% in the acupuncture and sham groups. The RCT by Kerr et al31 had a large difference in dropout rates between groups (acupuncture, 13%; control, 33%) but was excluded in the sensitivity analysis for blinding.
Forest plots for acupuncture against sham acupuncture and against no-acupuncture control are shown separately for each of the 4 pain conditions in Figure 2 and Figure 3. Meta-analytic statistics are shown in Table 2. Acupuncture was statistically superior to control for allanalyses (P < .001). Effect sizes are larger for the comparison between acupuncture and no-acupuncture control than for the comparison between acupuncture and sham: 0.37, 0.26, and 0.15 in comparison with sham vs 0.55, 0.57, and 0.42 in comparison with no-acupuncture control for musculoskeletal pain, osteoarthritis, and chronic headache, respectively.
For 5 of the 7 analyses, the test for heterogeneity was statistically significant. In the case of comparisons with sham acupuncture, the RCTs by Vas et al37,38,41 are clear outliers. For example, the effect size of the RCTs by Vas et al for neck pain is about 5 times greater than meta-analytic estimate. One effect of excluding these RCTs in a sensitivity analysis (Table 3 and Table 4) is that there is no significant heterogeneity in the comparisons between acupuncture and sham. Moreover, the effect size for acupuncture becomes relatively similar for the different pain conditions: 0.23, 0.16, and 0.15 against sham, and 0.55, 0.57, and 0.42 against no-acupuncture control for back and neck pain, osteoarthritis, and chronic headache, respectively (fixed effects; results similar for the random effects analysis).
To give an example of what these effect sizes mean in real terms, a baseline pain score on a 0 to 100 scale for a typical RCT might be 60. Given a standard deviation of 25, follow-up scores might be 43 in a no-acupuncture group, 35 in a sham acupuncture group, and 30 in patients receiving true acupuncture. If response were defined in terms of a pain reduction of 50% or more, response rates would be approximately 30%, 42.5%, and 50%, respectively.
The comparisons with no-acupuncture control show evidence of heterogeneity. This seems largely explicable in terms of differences between the control groups used. In the case of osteoarthritis, the largest effect was in the study by Witt et al,17 in which patients in the waiting list control received only rescue pain medication, and the smallest was in the study by Foster et al,24 which involved a program of exercise and advice led by physical therapists. For the musculoskeletal analyses, heterogeneity is driven by 2 very large RCTs19,20 (n = 2565 patients and n = 3118 patients, respectively) for back and neck pain. If only back pain is considered (Table 3 and Table 4), heterogeneity is dramatically reduced and is again driven by one RCT, by Brinkhaus et al,15 with waiting list control. In the headache meta-analysis, Diener et al13 had much smaller differences between groups. This RCT involved providing drug therapy according to national guidelines in the no-acupuncture group, including initiation of β-blockers as migraine prophylaxis. There was disagreement within the collaboration about whether this constituted active control. Excluding this RCT reduced evidence of heterogeneity (P = .04) but had little effect on the effect size (0.42-0.45).
Table 3 and Table 4 show several prespecified sensitivity analyses. Neither restricting the sham RCTs to those with low likelihood of unblinding nor adjustment for missing data had any substantive effect on our main estimates. Inclusion of summary data from RCTs for which raw data were not obtained (2 RCTs) or which were published recently (4 RCTs) also had little impact on either the primary analysis (Table 3 and Table 4) or the analysis with the outlying RCTs by Vas et al37,38,41 excluded (data not shown).
To estimate the potential impact of publication bias, we entered all RCTs into a single analysis and compared the effect sizes from small and large studies.99 We saw some evidence that small studies had larger effect sizes for the comparison with sham (P = .02) but not no-acupuncture control (P = .72). However, these analyses are influenced by the outlying RCTs by Vas et al,37,38,41 which were smaller than average, and by indication, because the shoulder pain RCTs were small and had large effect sizes. Tests for asymmetry were nonsignificant when we excluded the RCTs by Vas et al37,38,41 and shoulder pain studies (n = 15; P = .07) and when small studies were also excluded (n < 100 and n = 12, respectively; P = .30). Nonetheless, we repeated our meta-analyses excluding RCTs with a sample size of less than 100. This had essentially no effect on our results. As a further test of publication bias, we considered the possible effect on our analysis if we had failed to include high-quality, unpublished studies. Only if there were 47 unpublished RCTs with n = 100 patients showing an advantage to sham of 0.25 SD would the difference between acupuncture and sham lose significance.
A final sensitivity analysis examined the effect of pooling different end points measured at different periods of follow-up. We repeated our analyses including only pain end points measured at 2 to 3 months after randomization. There was no material effect on results: effect sizes increased by 0.05 to 0.09 SD for musculoskeletal and osteoarthritis RCTs and were stable otherwise.
As an exploratory analysis, we compared sham control with no-acupuncture control. In a meta-analysis of 9 RCTs,11-13,15-18,24,28 the effect size for sham was 0.33 (95% CI, 0.27-0.40) and 0.38 (95% CI, 0.20-0.56) for fixed and random effects models, respectively (P < .001 for tests of both effect and heterogeneity).
In an analysis of patient-level data from 29 high-quality RCTs, including 17 922 patients, we found statistically significant differences between both acupuncture vs sham and acupuncture vs no-acupuncture control for all pain types studied. After excluding an outlying set of studies, meta-analytic effect sizes were similar across pain conditions.
The effect size for individual RCTs comparing acupuncture with no-acupuncture control did vary, an effect that seems at least partly explicable in terms of the type of control used. As might be expected, acupuncture had a smaller benefit in patients who received a program of ancillary care—such as physical therapist–led exercise24—than in patients who continued to be treated with usual care. Nonetheless, the average effect, as expressed in the meta-analytic estimate of approximately 0.5 SD, is of clear clinical relevance whether considered either as a standardized difference100 or when converted back to a pain scale. The difference between acupuncture and sham is of lesser magnitude, 0.15 to 0.23 SD.
Neither study quality nor sample size seems to be a problem for this meta-analysis, on the grounds that only high-quality studies were eligible and the total sample size is large. Moreover, we saw no evidence that publication bias, or failure to identify published eligible studies, could affect our conclusions.
Because the comparisons between acupuncture and no-acupuncture cannot be blinded, both performance and response bias are possible. Similarly, while we considered the risk of bias of unblinding low in most studies comparing acupuncture and sham acupuncture, health care providers obviously were aware of the treatment provided, and, as such, a certain degree of bias of our effect estimate for specific effects cannot be entirely ruled out. However, it should be kept in mind that this problem applies to almost all studies on nondrug interventions. We would argue that the risk of bias in the comparison between acupuncture and sham acupuncture is low compared with other nondrug treatments for chronic pain, such as cognitive therapies, exercise, or manipulation, which are rarely subject to placebo control.
Another possible critique is that the meta-analyses combined different end points, such as pain and function, measured at different times. However, results did not change when we restricted the analysis to pain end points measured at a specific follow-up time, 2 to 3 months after randomization.
Comparison with other studies
Many prior systematic reviews of acupuncture for chronic pain have had liberal eligibility criteria, accordingly included RCTs of low methodologic quality, and then came to the circular conclusion that weaknesses in the data did not allow conclusions to be drawn.101,102 Other reviews have not included meta-analyses, apparently owing to variation in study end points.103,104 We have avoided both problems by including only high-quality RCTs and obtaining raw data for individual patient data meta-analysis. Some more recent systematic reviews have published meta-analyses105-108 and reported findings that are broadly comparable with ours, with clear differences between acupuncture and no-acupuncture control and smaller differences between true and sham acupuncture. Our findings have greater precision: all prior reviews have analyzed summary data, an approach of reduced statistical precision when compared with individual patient data meta-analysis.6,109 In particular, we have demonstrated a robust difference between acupuncture and sham control that can be distinguished from bias. This is a novel finding that moves beyond the prior literature.
We believe that our findings are both clinically and scientifically important. They suggest that the total effects of acupuncture, as experienced by the patient in routine clinical practice, are clinically relevant, but that an important part of these total effects is not due to issues considered to be crucial by most acupuncturists, such as the correct location of points and depth of needling. Several lines of argument suggest that acupuncture (whether real or sham) is associated with more potent placebo or context effects than other interventions.110-113 Yet, many clinicians would feel uncomfortable in providing or referring patients to acupuncture if it were merely a potent placebo. Similarly, it is questionable whether national or private health insurance should reimburse therapies that do not have specific effects. Our finding that acupuncture has effects over and above those of sham acupuncture is therefore of major importance for clinical practice. Even though on average these effects are small, the clinical decision made by physicians and patients is not between true and sham acupuncture but between a referral to an acupuncturist or avoiding such a referral. The total effects of acupuncture, as experienced by the patient in routine practice, include both the specific effects associated with correct needle insertion according to acupuncture theory, nonspecific physiologic effects of needling, and nonspecific psychological (placebo) effects related to the patient's belief that treatment will be effective.
In conclusion, we found acupuncture to be superior to both no-acupuncture control and sham acupuncture for the treatment of chronic pain. Although the data indicate that acupuncture is more than a placebo, the differences between true and sham acupuncture are relatively modest, suggesting that factors in addition to the specific effects of needling are important contributors to therapeutic effects. Our results from individual patient data meta-analyses of nearly 18 000 randomized patients in high-quality RCTs provide the most robust evidence to date that acupuncture is a reasonable referral option for patients with chronic pain.
Correspondence: Andrew J. Vickers, DPhil, Department of Epidemiology and Biostatistics, Memorial Sloan-Kettering Cancer Center, 307 E 63rd St, New York, NY 10065 (firstname.lastname@example.org).
Accepted for Publication: May 28, 2012.
Published Online: September 10, 2012. doi:10.1001/archinternmed.2012.3654
Author Contributions: Dr Vickers had full access to all of the data inthe study and takes responsibility for the integrity of the data and the accuracy of the data analysis. All authors gave comments on early drafts and approved the final version of the manuscript. Study concept and design: Vickers, Lewith, Foster, Witt, and Linde. Acquisition of data: Vickers, Maschino, MacPherson, Foster, and Witt. Analysis and interpretation of data: Vickers, Cronin, Maschino, Lewith, MacPherson, Foster, Sherman, Witt, and Linde. Drafting of the manuscript: Vickers and Maschino. Critical revision of the manuscript for important intellectual content: Vickers, Cronin, Maschino, Lewith, MacPherson, Foster, Sherman, Witt, and Linde. Statistical analysis: Vickers, Cronin, and Maschino. Obtained funding: Vickers and Linde. Administrative, technical, and material support: Lewith. Study supervision: Vickers.
Financial Disclosure: None reported.
Funding/Support: The Acupuncture Trialists' Collaboration is funded by an R21 (AT004189I from the National Center for Complementary and Alternative Medicine (NCCAM) at the National Institutes of Health (NIH) to Dr Vickers) and by a grant from the Samueli Institute. Dr MacPherson's work has been supported in part by the UK National Institute for Health Research (NIHR) under its Programme Grants for Applied Research scheme (RP-PG-0707-10186). The views expressed in this publication are those of the author(s) and not necessarily those of the NCCAM NHS, the NIHR, or the Department of Health in England.
Role of the Sponsors: No sponsor had any role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; and preparation, review, or approval of the manuscript.
The Acupuncture Trialists' Collaboration: Claire Allen, BS, Cochrane Collaboration Secretariat, Oxford, England; Mac Beckner, MIS, Information Technology and Data Management Center, Samueli Institute, Alexandria, Virginia; Brian Berman, MD, University of Maryland School of Medicine and Center for Integrative Medicine, College Park; Benno Brinkhaus, MD, Institute for Social Medicine, Epidemiology and Health Economics, Charité–University Medical Center, Berlin, Germany; Remy Coeytaux, MD, PhD, Department of Community and Family Medicine, Duke University, Durham, North Carolina; Angel M. Cronin, MS, Dana-Farber Cancer Institute, Boston, Massachusetts; Hans-Christoph Diener, MD, PhD, Department of Neurology, University of Duisburg-Essen, Germany; Heinz G. Endres, MD, Ruhr–University Bochum, Bochum, Germany; Nadine Foster, DPhil, BSc(Hons), Arthritis Research UK Primary Care Centre, Keele University, Newcastle-under-Lyme, Staffordshire, England; Juan Antonio Guerra de Hoyos, MD, Andalusian Integral Plan for Pain Management, and Andalusian Health Service Project for Improving Primary Care Research, Sevilla, Spain; Michael Haake, MD, PhD, Department of Orthopedics and Traumatology, SLK-Hospitals, Heilbronn, Germany; Richard Hammerschlag, PhD, Oregon College of Oriental Medicine, Portland; Dominik Irnich, MD, Interdisciplinary Pain Centre, University of Munich, Munich, Germany; Wayne B. Jonas, MD, Samueli Institute; Kai Kronfeld, PhD, Interdisciplinary Centre for Clinical Trials (IZKS Mainz), University Medical Centre Mainz, Mainz, Germany; Lixing Lao, PhD, University of Maryland and Center for Integrative Medicine, College Park; George Lewith, MD, FRCP, Complementary and Integrated Medicine Research Unit, Southampton Medical School, Southampton, England; Klaus Linde, MD, Institute of General Practice, Technische Universität München, Munich; Hugh MacPherson, PhD, Complementary Medicine Research Group, University of York, York, England; Eric Manheimer, MS, Center for Integrative Medicine, University of Maryland School of Medicine, College Park; Alexandra Maschino, BS, Memorial Sloan-Kettering Cancer Center, New York, New York; Dieter Melchart, MD, PhD, Centre for Complementary Medicine Research (Znf), Technische Universität München, Munich; Albrecht Molsberger, MD, PhD, German Acupuncture Research Group, Duesseldorf, Germany; Karen J. Sherman, PhD, MPH, Group Health Research Institute, Seattle, Washington; Hans Trampisch, PhD, Department of Medical Statistics and Epidemiology, Ruhr–University Bochum; Jorge Vas, MD, PhD, Pain Treatment Unit, Dos Hermanas Primary Care Health Center (Andalusia Public Health System), Dos Hermanas, Spain; Andrew J. Vickers (collaboration chair), DPhil, Memorial Sloan-Kettering Cancer Center; Norbert Victor, PhD (deceased), Institute of Medical Biometrics and Informatics, University of Heidelberg, Heidelberg, Germany; Peter White, PhD, School of Health Sciences, University of Southampton; Lyn Williamson, MD, MA (Oxon), MRCGP, FRCP, Great Western Hospital, Swindon, and Oxford University, Oxford, England; Stefan N. Willich, MD, MPH, MBA, Institute for Social Medicine, Epidemiology, and Health Economics, Charité University Medical Center, Berlin; Claudia M. Witt, MD, MBA, University Medical Center Charité and Institute for Social Medicine, Epidemiology and Health Economics, Berlin.
White A.Editorial Board of Acupuncture in Medicine. Western medical acupuncture: a definition. Acupunct Med
. 2009;27(1):33-3519369193PubMedGoogle ScholarCrossref
Barnes PM, Bloom B, Nahin RL. Complementary and alternative medicine use among adults and children: United States, 2007. Natl Health Stat Report
. 2008;(12):1-2319361005PubMedGoogle Scholar
Sherman KJ, Cherkin DC, Eisenberg DM, Erro J, Hrbek A, Deyo RA. The practice of acupuncture: who are the providers and what do they do? Ann Fam Med
. 2005;3(2):151-15815798042PubMedGoogle ScholarCrossref
Peets JM, Pomeranz B. CXBK mice deficient in opiate receptors show poor electroacupuncture analgesia. Nature
. 1978;273(5664):675-676208000PubMedGoogle ScholarCrossref
Zhang WT, Jin Z, Luo F, Zhang L, Zeng YW, Han JS. Evidence from brain imaging with fMRI supporting functional specificity of acupoints in humans. Neurosci Lett
. 2004;354(1):50-5314698480PubMedGoogle ScholarCrossref
Vickers AJ, Cronin AM, Maschino AC,
et al; Acupuncture Trialists' Collaboration. Individual patient data meta-analysis of acupuncture for chronic pain: protocol of the Acupuncture Trialists' Collaboration. Trials
. 2010;11:9020920180PubMedGoogle ScholarCrossref
Schulz KF, Chalmers I, Hayes RJ, Altman DG. Empirical evidence of bias: dimensions of methodological quality associated with estimates of treatment effects in controlled trials. JAMA
. 1995;273(5):408-4127823387PubMedGoogle ScholarCrossref
Streitberger K, Kleinhenz J. Introducing a placebo needle into acupuncture research. Lancet
. 1998;352(9125):364-3659717924PubMedGoogle ScholarCrossref
Frison L, Pocock SJ. Repeated measures in clinical trials: analysis using mean summary statistics and its implications for design. Stat Med
. 1992;11(13):1685-17041485053PubMedGoogle ScholarCrossref
Vickers AJ. Statistical reanalysis of four recent randomized trials of acupuncture for pain using analysis of covariance. Clin J Pain
. 2004;20(5):319-32315322438PubMedGoogle ScholarCrossref
Scharf HP, Mansmann U, Streitberger K,
et al. Acupuncture and knee osteoarthritis: a three-armed randomized trial. Ann Intern Med
. 2006;145(1):12-2016818924PubMedGoogle Scholar
Haake M, Müller HH, Schade-Brittinger C,
et al. German Acupuncture Trials (GERAC) for chronic low back pain: randomized, multicenter, blinded, parallel-group trial with 3 groups. Arch Intern Med
. 2007;167(17):1892-189817893311PubMedGoogle ScholarCrossref
Diener HC, Kronfeld K, Boewing G,
et al; GERAC Migraine Study Group. Efficacy of acupuncture for the prophylaxis of migraine: a multicentre randomised controlled clinical trial. Lancet Neurol
. 2006;5(4):310-31616545747PubMedGoogle ScholarCrossref
Endres HG, Böwing G, Diener HC,
et al. Acupuncture for tension-type headache: a multicentre, sham-controlled, patient-and observer-blinded, randomised trial. J Headache Pain
. 2007;8(5):306-31417955168PubMedGoogle ScholarCrossref
Brinkhaus B, Witt CM, Jena S,
et al. Acupuncture in patients with chronic low back pain: a randomized controlled trial. Arch Intern Med
. 2006;166(4):450-45716505266PubMedGoogle Scholar
Melchart D, Streng A, Hoppe A,
et al. Acupuncture in patients with tension-type headache: randomised controlled trial. BMJ
. 2005;331(7513):376-38216055451PubMedGoogle ScholarCrossref
Witt C, Brinkhaus B, Jena S,
et al. Acupuncture in patients with osteoarthritis of the knee: a randomised trial. Lancet
. 2005;366(9480):136-14316005336PubMedGoogle ScholarCrossref
Linde K, Streng A, Jürgens S,
et al. Acupuncture for patients with migraine: a randomized controlled trial. JAMA
. 2005;293(17):2118-212515870415PubMedGoogle ScholarCrossref
Witt CM, Jena S, Selim D,
et al. Pragmatic randomized trial evaluating the clinical and economic effectiveness of acupuncture for chronic low back pain. Am J Epidemiol
. 2006;164(5):487-49616798792PubMedGoogle ScholarCrossref
Witt CM, Jena S, Brinkhaus B, Liecker B, Wegscheider K, Willich SN. Acupuncture for patients with chronic neck pain. Pain
. 2006;125(1-2):98-10616781068PubMedGoogle ScholarCrossref
Jena S, Witt CM, Brinkhaus B, Wegscheider K, Willich SN. Acupuncture in patients with headache. Cephalalgia
. 2008;28(9):969-97918624803PubMedGoogle ScholarCrossref
Witt CM, Jena S, Brinkhaus B, Liecker B, Wegscheider K, Willich SN. Acupuncture in patients with osteoarthritis of the knee or hip: a randomized, controlled trial with an additional nonrandomized arm. Arthritis Rheum
. 2006;54(11):3485-349317075849PubMedGoogle ScholarCrossref
Thomas KJ, MacPherson H, Thorpe L,
et al. Randomised controlled trial of a short course of traditional acupuncture compared with usual care for persistent non-specific low back pain. BMJ
. 2006;333(7569):62316980316PubMedGoogle ScholarCrossref
Foster NE, Thomas E, Barlas P,
et al. Acupuncture as an adjunct to exercise based physiotherapy for osteoarthritis of the knee: randomised controlled trial. BMJ
. 2007;335(7617):43617699546PubMedGoogle ScholarCrossref
Kleinhenz J, Streitberger K, Windeler J, Güssbacher A, Mavridis G, Martin E. Randomised clinical trial comparing the effects of acupuncture and a newly designed placebo needle in rotator cuff tendinitis. Pain
. 1999;83(2):235-24110534595PubMedGoogle ScholarCrossref
White P, Lewith G, Prescott P, Conway J. Acupuncture versus placebo for the treatment of chronic mechanical neck pain: a randomized, controlled trial. Ann Intern Med
. 2004;141(12):911-91915611488PubMedGoogle Scholar
Irnich D, Behrens N, Molzen H,
et al. Randomised trial of acupuncture compared with conventional massage and “sham” laser acupuncture for treatment of chronic neck pain. BMJ
. 2001;322(7302):1574-157811431299PubMedGoogle ScholarCrossref
Berman BM, Lao L, Langenberg P, Lee WL, Gilpin AM, Hochberg MC. Effectiveness of acupuncture as adjunctive therapy in osteoarthritis of the knee: a randomized, controlled trial. Ann Intern Med
. 2004;141(12):901-91015611487PubMedGoogle Scholar
Coeytaux RR, Kaufman JS, Kaptchuk TJ,
et al. A randomized, controlled trial of acupuncture for chronic daily headache. Headache
. 2005;45(9):1113-112316178942PubMedGoogle ScholarCrossref
Molsberger AF, Mau J, Pawelec DB, Winkler J. Does acupuncture improve the orthopedic management of chronic low back pain: a randomized, blinded, controlled trial with 3 months follow up. Pain
. 2002;99(3):579-58712406534PubMedGoogle ScholarCrossref
Kerr DP, Walsh DM, Baxter D. Acupuncture in the management of chronic low back pain: a blinded randomized controlled trial. Clin J Pain
. 2003;19(6):364-37014600536PubMedGoogle ScholarCrossref
Carlsson CP, Sjölund BH. Acupuncture for chronic low back pain: a randomized placebo-controlled study with long-term follow-up. Clin J Pain
. 2001;17(4):296-30511783809PubMedGoogle ScholarCrossref
Vickers AJ, Rees RW, Zollman CE,
et al. Acupuncture for chronic headache in primary care: large, pragmatic, randomised trial. BMJ
. 2004;328(7442):74415023828PubMedGoogle ScholarCrossref
Kennedy S, Baxter GD, Kerr DP, Bradbury I, Park J, McDonough SM. Acupuncture for acute non-specific low back pain: a pilot randomised non-penetrating sham controlled trial. Complement Ther Med
. 2008;16(3):139-14618534326PubMedGoogle ScholarCrossref
Cherkin DC, Eisenberg D, Sherman KJ,
et al. Randomized trial comparing traditional Chinese medical acupuncture, therapeutic massage, and self-care education for chronic low back pain. Arch Intern Med
. 2001;161(8):1081-108811322842PubMedGoogle ScholarCrossref
Salter GC, Roman M, Bland MJ, MacPherson H. Acupuncture for chronic neck pain: a pilot for a randomised controlled trial. BMC Musculoskelet Disord
. 2006;7:9917156464PubMedGoogle ScholarCrossref
Vas J, Perea-Milla E, Méndez C,
et al. Efficacy and safety of acupuncture for chronic uncomplicated neck pain: a randomised controlled study. Pain
. 2006;126(1-3):245-25516934402PubMedGoogle ScholarCrossref
Vas J, Méndez C, Perea-Milla E,
et al. Acupuncture as a complementary therapy to the pharmacological treatment of osteoarthritis of the knee: randomised controlled trial. BMJ
. 2004;329(7476):121615494348PubMedGoogle ScholarCrossref
Williamson L, Wyatt MR, Yein K, Melton JT. Severe knee osteoarthritis: a randomized controlled trial of acupuncture, physiotherapy (supervised exercise) and standard management for patients awaiting knee replacement. Rheumatology (Oxford)
. 2007;46(9):1445-144917604311PubMedGoogle ScholarCrossref
Guerra de Hoyos JA, Andrés Martín MdelC, Bassas y Baena de Leon E,
et al. Randomised trial of long term effect of acupuncture for shoulder pain. Pain
. 2004;112(3):289-29815561384PubMedGoogle ScholarCrossref
Vas J, Ortega C, Olmo V,
et al. Single-point acupuncture and physiotherapy for the treatment of painful shoulder: a multicentre randomized controlled trial. Rheumatology (Oxford)
. 2008;47(6):887-89318403402PubMedGoogle ScholarCrossref
Zheng Z, Guo RJ, Helme RD, Muir A, Da Costa C, Xue CC. The effect of electroacupuncture on opioid-like medication consumption by chronic pain patients: a pilot randomized controlled clinical trial. Eur J Pain
. 2008;12(5):671-67618035566PubMedGoogle ScholarCrossref
Coan RM, Wong G, Coan PL. The acupuncture treatment of neck pain: a randomized controlled study. Am J Chin Med
. 1981;9(4):326-3327053030PubMedGoogle ScholarCrossref
França DL, Senna-Fernandes V, Cortez CM, Jackson MN, Bernardo-Filho M, Guimarães MA. Tension neck syndrome treated by acupuncture combined with physiotherapy: a comparative clinical trial (pilot study). Complement Ther Med
. 2008;16(5):268-27718765182PubMedGoogle ScholarCrossref
Ezzo J, Vickers A, Richardson MA,
et al. Acupuncture-point stimulation for chemotherapy-induced nausea and vomiting. J Clin Oncol
. 2005;23(28):7188-719816192603PubMedGoogle ScholarCrossref
He D, Veiersted KB, Høstmark AT, Medbø JI. Effect of acupuncture treatment on chronic neck and shoulder pain in sedentary female workers: a 6-month and 3-year follow-up study. Pain
. 2004;109(3):299-30715157691PubMedGoogle ScholarCrossref
Razavi M, Jansen GB. Effects of acupuncture and placebo TENS in addition to exercise in treatment of rotator cuff tendinitis. Clin Rehabil
. 2004;18(8):872-87815609842PubMedGoogle ScholarCrossref
Grant DJ, Bishop-Miller J, Winchester DM, Anderson M, Faulkner S. A randomized comparative trial of acupuncture versus transcutaneous electrical nerve stimulation for chronic back pain in the elderly. Pain
. 1999;82(1):9-1310422654PubMedGoogle ScholarCrossref
Itoh K, Katsumi Y, Kitakoji H. Trigger point acupuncture treatment of chronic low back pain in elderly patients: a blinded RCT. Acupunct Med
. 2004;22(4):170-17715628774PubMedGoogle ScholarCrossref
Johansson KM, Adolfsson LE, Foldevi MO. Effects of acupuncture versus ultrasound in patients with impingement syndrome: randomized clinical trial. Phys Ther
. 2005;85(6):490-50115921471PubMedGoogle Scholar
Streng A, Linde K, Hoppe A,
et al. Effectiveness and tolerability of acupuncture compared with metoprolol in migraine prophylaxis. Headache
. 2006;46(10):1492-150217115982PubMedGoogle ScholarCrossref
David J, Modi S, Aluko AA, Robertshaw C, Farebrother J. Chronic neck pain: a comparison of acupuncture treatment and physiotherapy. Br J Rheumatol
. 1998;37(10):1118-11229825752PubMedGoogle ScholarCrossref
Ga H, Choi JH, Park CH, Yoon HJ. Acupuncture needling versus lidocaine injection of trigger points in myofascial pain syndrome in elderly patients: a randomised trial. Acupunct Med
. 2007;25(4):130-13618160923PubMedGoogle ScholarCrossref
Ng MM, Leung MC, Poon DM. The effects of electro-acupuncture and transcutaneous electrical nerve stimulation on patients with painful osteoarthritic knees: a randomized controlled trial with follow-up evaluation. J Altern Complement Med
. 2003;9(5):641-64914629842PubMedGoogle ScholarCrossref
Melchart D, Hager S, Hager U, Liao J, Weidenhammer W, Linde K. Treatment of patients with chronic headaches in a hospital for traditional Chinese medicine in Germany: a randomised, waiting list controlled trial. Complement Ther Med
. 2004;12(2-3):71-7815561516PubMedGoogle ScholarCrossref
Weiner DK, Rudy TE, Morone N, Glick R, Kwoh CK. Efficacy of periosteal stimulation therapy for the treatment of osteoarthritis-associated chronic knee pain: an initial controlled clinical trial. J Am Geriatr Soc
. 2007;55(10):1541-154717908057PubMedGoogle ScholarCrossref
Inoue M, Kitakoji H, Ishizaki N,
et al. Relief of low back pain immediately after acupuncture treatment: a randomised, placebo controlled trial. Acupunct Med
. 2006;24(3):103-10817013356PubMedGoogle ScholarCrossref
Nabeta T, Kawakita K. Relief of chronic neck and shoulder pain by manual acupuncture to tender points: a sham-controlled randomized trial. Complement Ther Med
. 2002;10(4):217-22212594972PubMedGoogle ScholarCrossref
Berry H, Fernandes L, Bloom B, Clark RJ, Hamilton EB. Clinical study comparing acupuncture, physiotherapy, injection and oral anti-inflammatory therapy in shoulder-cuff lesions. Curr Med Res Opin
. 1980;7(2):121-1267002481PubMedGoogle ScholarCrossref
Fernandes L, Berry N, Clark RJ, Bloom B, Hamilton EB. Clinical study comparing acupuncture, physiotherapy, injection, and oral anti-inflammatory therapy in shoulder-cuff lesions. Lancet
. 1980;1(8161):208-2096153441PubMedGoogle ScholarCrossref
Moore ME, Berk SN. Acupuncture for chronic shoulder pain: an experimental study with attention to the role of placebo and hypnotic susceptibility. Ann Intern Med
. 1976;84(4):381-384769630PubMedGoogle Scholar
Ma T, Kao MJ, Lin IH,
et al. A study on the clinical effects of physical therapy and acupuncture to treat spontaneous frozen shoulder. Am J Chin Med
. 2006;34(5):759-77517080543PubMedGoogle ScholarCrossref
Giles LG, Müller R. Chronic spinal pain syndromes: a clinical pilot trial comparing acupuncture, a nonsteroidal anti-inflammatory drug, and spinal manipulation. J Manipulative Physiol Ther
. 1999;22(6):376-38110478769PubMedGoogle ScholarCrossref
Melchart D, Thormaehlen J, Hager S, Liao J, Linde K, Weidenhammer W. Acupuncture versus placebo versus sumatriptan for early treatment of migraine attacks: a randomized controlled trial. J Intern Med
. 2003;253(2):181-18812542558PubMedGoogle ScholarCrossref
Coan RM, Wong G, Ku SL,
et al. The acupuncture treatment of low back pain: a randomized controlled study. Am J Chin Med
. 1980;8(1-2):181-1896446852PubMedGoogle ScholarCrossref
Christensen BV, Iuhl IU, Vilbek H, Bülow HH, Dreijer NC, Rasmussen HF. Acupuncture treatment of severe knee osteoarthrosis: a long-term study. Acta Anaesthesiol Scand
. 1992;36(6):519-5251514335PubMedGoogle ScholarCrossref
Molsberger A, Böwing G, Jensen KU, Lorek M. Acupuncture treatment for the relief of gonarthrosis pain: a controlled clinical trial. Schmerz
. 1994;8(1):37-4218415453PubMedGoogle ScholarCrossref
Linde M, Fjell A, Carlsson J, Dahlöf C. Role of the needling per se in acupuncture as prophylaxis for menstrually related migraine: a randomized placebo-controlled study. Cephalalgia
. 2005;25(1):41-4715606569PubMedGoogle ScholarCrossref
Muller R, Giles LG. Long-term follow-up of a randomized clinical trial assessing the efficacy of medication, acupuncture, and spinal manipulation for chronic mechanical spinal pain syndromes. J Manipulative Physiol Ther
. 2005;28(1):3-1115726029PubMedGoogle ScholarCrossref
Sator-Katzenschlager SM, Scharbert G, Kozek-Langenecker SA,
et al. The short- and long-term benefit in chronic low back pain through adjuvant electrical versus manual auricular acupuncture. Anesth Analg
. 2004;98(5):1359-136415105215PubMedGoogle ScholarCrossref
Karst M, Reinhard M, Thum P, Wiese B, Rollnik J, Fink M. Needle acupuncture in tension-type headache: a randomized, placebo-controlled study. Cephalalgia
. 2001;21(6):637-64211531895PubMedGoogle ScholarCrossref
Ceccherelli F, Bordin M, Gagliardi G, Caravello M. Comparison between superficial and deep acupuncture in the treatment of the shoulder's myofascial pain: a randomized and controlled study. Acupunct Electrother Res
. 2001;26(4):229-23811841108PubMedGoogle Scholar
Ceccherelli F, Rigoni MT, Gagliardi G, Ruzzante L. Comparison of superficial and deep acupuncture in the treatment of lumbar myofascial pain: a double-blind randomized controlled study. Clin J Pain
. 2002;18(3):149-15312048416PubMedGoogle ScholarCrossref
Naprienko MV, Oknin VIu, Kremenchugskaia MR, Filatova EG. Use of acupuncture in the therapy of chronic daily headache. Zh Nevrol Psikhiatr Im S S Korsakova
. 2003;103(10):40-4414628586PubMedGoogle Scholar
Leibing E, Leonhardt U, Köster G,
et al. Acupuncture treatment of chronic low-back pain: a randomized, blinded, placebo-controlled trial with 9-month follow-up. Pain
. 2002;96(1-2):189-19611932074PubMedGoogle ScholarCrossref
Meng CF, Wang D, Ngeow J, Lao L, Peterson M, Paget S. Acupuncture for chronic low back pain in older patients: a randomized, controlled trial. Rheumatology (Oxford)
. 2003;42(12):1508-151712890859PubMedGoogle ScholarCrossref
Berman BM, Singh BB, Lao L,
et al. A randomized trial of acupuncture as an adjunctive therapy in osteoarthritis of the knee. Rheumatology (Oxford)
. 1999;38(4):346-35410378713PubMedGoogle ScholarCrossref
Takeda W, Wessel J. Acupuncture for the treatment of pain of osteoarthritic knees. Arthritis Care Res
. 1994;7(3):118-1227727550PubMedGoogle ScholarCrossref
Tukmachi E, Jubb R, Dempsey E, Jones P. The effect of acupuncture on the symptoms of knee osteoarthritis: an open randomised controlled study. Acupunct Med
. 2004;22(1):14-2215077933PubMedGoogle ScholarCrossref
Itoh K, Hirota S, Katsumi Y, Ochi H, Kitakoji H. A pilot study on using acupuncture and transcutaneous electrical nerve stimulation (TENS) to treat knee osteoarthritis (OA). Chin Med
. 2008;3:218312661PubMedGoogle ScholarCrossref
Alecrim-Andrade J, Maciel-Júnior JA, Carnè X, Severino Vasconcelos GM, Correa-Filho HR. Acupuncture in migraine prevention: a randomized sham controlled study with 6-months posttreatment follow-up. Clin J Pain
. 2008;24(2):98-10518209514PubMedGoogle ScholarCrossref
Alecrim-Andrade J, Maciel-Júnior JA, Cladellas XC, Correa-Filho HR, Machado HC. Acupuncture in migraine prophylaxis: a randomized sham-controlled trial. Cephalalgia
. 2006;26(5):520-52916674760PubMedGoogle ScholarCrossref
Giles LG, Muller R. Chronic spinal pain: a randomized clinical trial comparing medication, acupuncture, and spinal manipulation. Spine (Phila Pa 1976)
. 2003;28(14):1490-150212865832PubMedGoogle Scholar
Itoh K, Hirota S, Katsumi Y, Ochi H, Kitakoji H. Trigger point acupuncture for treatment of knee osteoarthritis: a preliminary RCT for a pragmatic trial. Acupunct Med
. 2008;26(1):17-2618356795PubMedGoogle ScholarCrossref
Itoh K, Katsumi Y, Hirota S, Kitakoji H. Effects of trigger point acupuncture on chronic low back pain in elderly patients: a sham-controlled randomised trial. Acupunct Med
. 2006;24(1):5-1216618043PubMedGoogle ScholarCrossref
Itoh K, Katsumi Y, Hirota S, Kitakoji H. Randomised trial of trigger point acupuncture compared with other acupuncture for treatment of chronic neck pain. Complement Ther Med
. 2007;15(3):172-17917709062PubMedGoogle ScholarCrossref
Jubb RW, Tukmachi ES, Jones PW, Dempsey E, Waterhouse L, Brailsford S. 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
. 2008;26(2):69-7818591906PubMedGoogle ScholarCrossref
Stener-Victorin E, Kruse-Smidje C, Jung K. Comparison between electro-acupuncture and hydrotherapy, both in combination with patient education and patient education alone, on the symptomatic treatment of osteoarthritis of the hip. Clin J Pain
. 2004;20(3):179-18515100594PubMedGoogle ScholarCrossref
Tsui ML, Cheing GL. The effectiveness of electroacupuncture versus electrical heat acupuncture in the management of chronic low-back pain. J Altern Complement Med
. 2004;10(5):803-80915650469PubMedGoogle Scholar
Yeung CK, Leung MC, Chow DH. The use of electro-acupuncture in conjunction with exercise for the treatment of chronic low-back pain. J Altern Complement Med
. 2003;9(4):479-49014499023PubMedGoogle ScholarCrossref
Facco E, Liguori A, Petti F,
et al. Traditional acupuncture in migraine: a controlled, randomized study. Headache
. 2008;48(3):398-40717868354PubMedGoogle ScholarCrossref
White AR, Resch KL, Chan JC,
et al. Acupuncture for episodic tension-type headache: a multicentre randomized controlled trial. Cephalalgia
. 2000;20(7):632-63711128820PubMedGoogle ScholarCrossref
Sun KO, Chan KC, Lo SL, Fong DY. Acupuncture for frozen shoulder. Hong Kong Med J
. 2001;7(4):381-39111773673PubMedGoogle Scholar
Cherkin DC, Sherman KJ, Avins AL,
et al. A randomized trial comparing acupuncture, simulated acupuncture, and usual care for chronic low back pain. Arch Intern Med
. 2009;169(9):858-86619433697PubMedGoogle ScholarCrossref
Suarez-Almazor ME, Looney C, Liu Y,
et al. A randomized controlled trial of acupuncture for osteoarthritis of the knee: effects of patient-provider communication. Arthritis Care Res (Hoboken)
. 2010;62(9):1229-123620506122PubMedGoogle ScholarCrossref
Lansdown H, Howard K, Brealey S, MacPherson H. Acupuncture for pain and osteoarthritis of the knee: a pilot study for an open parallel-arm randomised controlled trial. BMC Musculoskelet Disord
. 2009;10:13019852841PubMedGoogle ScholarCrossref
Molsberger AF, Schneider T, Gotthardt H, Drabik A. German Randomized Acupuncture Trial for chronic shoulder pain (GRASP): a pragmatic, controlled, patient-blinded, multi-centre trial in an outpatient care environment. Pain
. 2010;151(1):146-15420655660PubMedGoogle ScholarCrossref
Wonderling D, Vickers AJ, Grieve R, McCarney R. Cost effectiveness analysis of a randomised trial of acupuncture for chronic headache in primary care. BMJ
. 2004;328(7442):74715023830PubMedGoogle ScholarCrossref
Egger M, Davey Smith G, Schneider M, Minder C. Bias in meta-analysis detected by a simple, graphical test. BMJ
. 1997;315(7109):629-6349310563PubMedGoogle ScholarCrossref
Sloan J. Asking the obvious questions regarding patient burden. J Clin Oncol
. 2002;20(1):4-611773146PubMedGoogle Scholar
Furlan AD, van Tulder MW, Cherkin DC,
et al. Acupuncture and dry-needling for low back pain. Cochrane Database Syst Rev
. 2005;(1):CD00135115674876PubMedGoogle Scholar
Green S, Buchbinder R, Hetrick S. Acupuncture for shoulder pain. Cochrane Database Syst Rev
. 2005;(2):CD00531915846753PubMedGoogle Scholar
White AR, Ernst E. A systematic review of randomized controlled trials of acupuncture for neck pain. Rheumatology (Oxford)
. 1999;38(2):143-14710342627PubMedGoogle ScholarCrossref
Ezzo J, Hadhazy V, Birch S,
et al. Acupuncture for osteoarthritis of the knee: a systematic review. Arthritis Rheum
. 2001;44(4):819-82511315921PubMedGoogle ScholarCrossref
Manheimer E, Cheng K, Linde K,
et al. Acupuncture for peripheral joint osteoarthritis. Cochrane Database Syst Rev
. 2010;(1):CD00197720091527PubMedGoogle Scholar
Linde K, Allais G, Brinkhaus B, Manheimer E, Vickers A, White AR. Acupuncture for tension-type headache. Cochrane Database Syst Rev
. 2009;(1):CD00758719160338PubMedGoogle Scholar
Linde K, Allais G, Brinkhaus B, Manheimer E, Vickers A, White AR. Acupuncture for migraine prophylaxis. Cochrane Database Syst Rev
. 2009;(1):CD00121819160193PubMedGoogle Scholar
Madsen MV, Gøtzsche PC, Hróbjartsson A. Acupuncture treatment for pain: systematic review of randomised clinical trials with acupuncture, placebo acupuncture, and no acupuncture groups. BMJ
. 2009;338:a311519174438PubMedGoogle ScholarCrossref
Riley RD, Lambert PC, Abo-Zaid G. Meta-analysis of individual participant data: rationale, conduct, and reporting. BMJ
. 2010;340:c22120139215PubMedGoogle ScholarCrossref
Kaptchuk TJ, Stason WB, Davis RB,
et al. Sham device v inert pill: randomised controlled trial of two placebo treatments. BMJ
. 2006;332(7538):391-39716452103PubMedGoogle ScholarCrossref
Linde K, Niemann K, Meissner K. Are sham acupuncture interventions more effective than (other) placebos? a re-analysis of data from the Cochrane Review
on placebo effects. Forsch Komplementmed
. 2010;17(5):259-26420980765PubMedGoogle ScholarCrossref
Kaptchuk TJ. The placebo effect in alternative medicine: can the performance of a healing ritual have clinical significance? Ann Intern Med
. 2002;136(11):817-82512044130PubMedGoogle Scholar
Liu T, Yu C-P. Placebo analgesia, acupuncture and sham surgery. eCAM
. 2010;1-6Google Scholar