Is acupuncture no more than a placebo? Extensive discussion required about possible bias

This review article addresses a fundamental question in acupuncture research: why do many studies suggest that acupuncture is no more effective than placebo? The Chinese authors, led by a team from the Tianjin University of Traditional Chinese Medicine, conducted a comprehensive analysis of the methodological problems that may bias the results of randomized controlled clinical trials in acupuncture. The work identifies three main categories of problems that can lead to erroneous conclusions about the efficacy of acupuncture: problems in study design, potent placebo effects, and inadequate administration of acupuncture. With regard to study design, the authors highlight common problems that also affect other areas of medicine, such as inadequate randomization, insufficient blinding, and high dropout rates.

Specifically in acupuncture, adequate randomization is found in only 26% of the studies analyzed, while adequate allocation concealment occurs in only 29% of cases. These problems can overestimate treatment effects by up to 41% when randomization is inadequate and by 17% when blinding is insufficient. A particular challenge for acupuncture research is the development of appropriate placebo controls. Unlike an inert pill, creating a truly inactive 'sham acupuncture' is extremely difficult.

All forms of sham control currently used — including superficial needling, incorrect points, non-traditional points, and non-penetrating needles — can produce some physiological effects. This reduces the observed difference between real and sham acupuncture, making it appear that acupuncture is no more effective than placebo. The placebo effect in acupuncture is particularly potent, being stronger than pill placebo. This is due to the complexity of the intervention, which involves an elaborate ritual, intense communication between practitioner and patient, and high expectations.

Neuroimaging studies demonstrate that real and sham acupuncture activate different brain patterns, suggesting distinct mechanisms of action. The inadequate administration of acupuncture represents another important and often overlooked bias. The authors compare two studies on hypertension with opposite results, demonstrating how different treatment protocols can dramatically influence outcomes. The study that showed benefits used 22 sessions over 6 weeks, with point selection based on traditional Chinese diagnosis, while the negative study used only up to 12 sessions over 6–8 weeks.

Point specificity and adequate needle manipulation are fundamental elements that are rarely objectively quantified in studies. Different manipulation techniques — including depth, intensity, duration, and frequency of stimulation — can produce distinct cellular and neurochemical effects. Experimental studies show that specific manipulations induce maximal responses in connective tissue and different patterns of neuropeptide release. The clinical implications of this work are significant for patients and researchers.

The authors argue that when methodological biases are adequately controlled — through rigorous design, minimization of the placebo effect, and optimization of acupuncture administration — studies can demonstrate significant differences between real acupuncture and placebo controls. This suggests that negative conclusions about the efficacy of acupuncture may reflect methodological limitations rather than real ineffectiveness of the intervention. For clinical practice, this means that patients should not dismiss acupuncture based solely on studies showing equivalence with placebo, especially if these studies present the methodological limitations discussed. The work proposes guidelines for future research, including the use of central randomization in multicenter studies, the development of better sham controls, strategies to minimize the placebo effect, and objective quantification of acupuncture protocols.

The authors emphasize the need for standardized guidelines for the optimal administration of acupuncture for different clinical conditions.