Effects of acupuncture versus placebo on clinical status and potential specific effects in Fibromyalgia: an umbrella review of 11 meta-analyses

Fibromyalgia is a complex condition that causes widespread pain, fatigue, and several other symptoms, affecting primarily women and representing a significant challenge in clinical management. This syndrome, which affects between 2% and 3% of the world population, is characterized by dysfunctions in pain processing by the central nervous system, resulting in symptoms that are difficult to treat effectively. Given the limitations of conventional treatments, many patients seek complementary therapies such as acupuncture, an ancient technique from traditional Chinese medicine that has gained increasing acceptance in the Western world. However, the actual efficacy of this practice remains controversial, especially when compared with placebo effects, raising fundamental questions about which benefits can be attributed specifically to the technique itself.

This study represents a broad and rigorous review of the scientific literature, known as an umbrella review, that systematically analyzed 11 previously published systematic reviews on acupuncture in fibromyalgia. The researchers examined a total of 8,399 participants, focusing on the comparison between true acupuncture and placebo or sham treatments. The methodology included comprehensive searches in eight international scientific databases, from inception through December 2023, selecting only studies of high methodological quality that compared acupuncture with placebo procedures in patients with a clinically confirmed diagnosis of fibromyalgia. The main outcomes analyzed were pain intensity, physical function, sleep quality, fatigue, and depressive symptoms.

An innovative feature of this study was the investigation of "contextual effects," that is, how much of the benefits observed cannot be attributed specifically to acupuncture, but rather to factors such as patient expectations, interaction with the therapist, and the therapeutic environment.

The results revealed a complex and nuanced picture of the efficacy of acupuncture. With regard to pain, the main symptom of fibromyalgia, acupuncture showed a statistically significant reduction of 1.13 centimeters on the visual analog scale compared with placebo. For fatigue, there was also a statistically significant improvement favoring acupuncture. However, for physical function and sleep quality, no significant differences were found between acupuncture and placebo.

A particularly relevant finding was that, although some improvements were statistically detectable, none reached the threshold considered clinically important — that is, a difference that would actually impact patients' daily lives. For example, for a pain reduction to be considered clinically relevant in fibromyalgia, it must be at least 2 points on the 0 to 10 scale, a value not reached in this study.

The most intriguing aspect of the research was the analysis of contextual effects, revealing that more than half of the benefits observed with acupuncture cannot be attributed to the specific technique. Specifically, 58% of the improvement in pain, 57% of the improvement in physical function, and an impressive 69% of the reduction in fatigue were considered contextual effects, related to factors such as positive patient expectations, quality of the therapeutic relationship, treatment environment, and other psychological and social elements. This finding aligns with established knowledge about how the therapeutic context can activate endogenous pain control systems, including the release of natural opioids and activation of brain areas involved in pain modulation.

For patients with fibromyalgia and healthcare professionals, these results have important practical implications. Although acupuncture may offer some modest benefits, especially for pain and fatigue, the improvements are small and a large part of the effect can be attributed to nonspecific factors of the technique. This does not mean that acupuncture should be discarded, but rather that patients and professionals should have realistic expectations. The contextual component identified suggests that any therapeutic intervention for fibromyalgia should value aspects such as empathic communication, a welcoming environment, and the building of realistic positive expectations.

For professionals, this reinforces the importance of a holistic approach that considers not only the specific technique, but the entire therapeutic context. Patients may benefit from acupuncture as part of a multimodal treatment plan, but should be aware that the effects are modest and that other treatments based on more robust evidence should also be considered.

It is essential to recognize the limitations identified by the authors. The methodological quality of the systematic reviews analyzed varied considerably, with several being classified as of low or very low quality. The heterogeneity among studies, including different types of acupuncture, treatment protocols, and durations, may have influenced the results. In addition, the inherently variable nature of fibromyalgia symptoms, with periods of exacerbation and spontaneous improvement, complicates the evaluation of any therapeutic intervention.

The limited number of studies for some outcomes also restricted the robustness of certain analyses. Despite these limitations, this study offers the most comprehensive synthesis available on acupuncture in fibromyalgia, providing a solid basis for informed clinical decisions. The authors emphasize the need for future clinical trials with more rigorous methodology, standardization of protocols, and long-term follow-up to better elucidate the role of acupuncture in the management of fibromyalgia.