Electric Stimulation for Pain Relief in Patients with Fibromyalgia: A Systematic Review and Meta-analysis of Randomized Controlled Trials
One page on PainSci cites Salazar 2017: Zapped! Does TENS work for pain?
PainSci commentary on Salazar 2017: ?This page is one of thousands in the PainScience.com bibliography. It is not a general article: it is focused on a single scientific paper, and it may provide only just enough context for the summary to make sense. Links to other papers and more general information are provided wherever possible.
This is a garbage-in-garbage-out meta-analysis of nine weak trials of stim for fibromyalgia, barely positive collectively. The effect sizes were statistically significant but well below any reasonable threshold for clinical significance, with the error bars extending to no effect at all. When a barely-there result like that is drawn from low quality trials, it’s probably doomed to evaporate when studied more rigorously. File under “meta-analysis is a misleading waste of time without better data to meta-analyze.”
Common issues and characteristics relevant to this paper: ?Scientific papers have many common characteristics, flaws, and limitations, and many of these are rarely or never acknowledged in the paper itself, or even by other reviewers. I have reviewed thousands of papers, and described many of these issues literally hundreds of times. Eventually I got sick of repeating myself, and so now I just refer to a list common characteristics, especially flaws. Not every single one of them applies perfectly to every paper, but if something is listed here, it is relevant in some way. Note that in the case of reviews, the issue may apply to the science being reviewed, and not the review itself.
- Garbage in, garbage out — not enough good quality data to meaningfully review/analyze.
- Damned with faint praise — technically positive results (at least partially) that don’t actually impress.
- Declares statistical significance without acknowledging low effect sizes. Major foul.
original abstract †Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.
BACKGROUND: Fibromyalgia (FM) is a syndrome whose primary symptoms include chronic widespread muscle pain and fatigue. The treatment of patients with FM aims to provide symptomatic relief and improvement in physical capacities to perform daily tasks and quality of life. Invasive or non-invasive electric stimulation (ES) is used for pain relief in patients with FM.
OBJECTIVE: This systematic review aimed to assess the effects of treatment with ES, combined or not combined with other types of therapy, for pain relief in patients with FM.
STUDY DESIGN: Systematic review and meta-analysis.
SETTING: Electronic search was conducted on databases (from the inception to April 2016): MEDLINE (accessed by PubMed), EMBASE, Cochrane Central Register of Controlled Trials (Cochrane CENTRAL), and Physiotherapy Evidence Database (PEDro).
METHODS: Two independent reviewers assessed the eligibility of studies based on the inclusion criteria: randomized controlled trials (RCTs) examining the effects of ES combined or not with other types of treatment for pain relief in patients with FM (according to the American College of Rheumatology), regardless of the ES dosages. The primary outcome was pain, assessed by the visual analogue scale (VAS). The secondary outcomes extracted were quality of life, assessed by short form-36 health survey (SF- 36), and fatigue, assessed by VAS.
RESULTS: Nine studies were included, with 301 patients. The meta-analysis for pain showed positive effect of ES treatment versus control [-1.24 (95% CI: -2.39 to -0.08; I²: 87%, P = 0.04) n = 8 RCTs]. The sensitivity analysis for pain showed significant results for invasive ES, combined or not with other types of therapy [-0.94 (95% CI, -1.50 to -0.38; I² 0%, P = 0.001) n = 3 RCTs]. No significant improvement was found regarding quality of life [-3.48 (95% CI: -12.58 to 5.62; I²: 0%, P = 0.45), n = 2 RCTs] or fatigue [-0.57 (95% CI, -1.25 to 0.11; I² 34%, P = 0.100; n = 4 RCTs].
LIMITATIONS: This systematic review included a small number of studies and reduced number of participants in each study. Furthermore, most of the studies showed some biases and lack of methodological quality.
CONCLUSIONS: This meta-analysis indicates that there is low-quality evidence for the effectiveness of ES for pain relief in patients with FM. However, moderate-quality evidence for the effectiveness of electroacupuncture (EA), combined or not combined with other types of treatment, was found for pain relief.
CLINICAL TRIAL REGISTRATION INFORMATION: PROSPERO under the identification CRD42015025323Key words: Electric stimulation, electroacupuncture, transcutaneous electric nerve stimulation, pain, fibromyalgia, review, physical therapy, rehabilitation.
This page is part of the PainScience BIBLIOGRAPHY, which contains plain language summaries of thousands of scientific papers & others sources. It’s like a highly specialized blog. A few highlights:
- Common interventional procedures for chronic non-cancer spine pain: a systematic review and network meta-analysis of randomised trials. Wang 2025 BMJ.
- Gabapentinoids and Risk of Hip Fracture. Leung 2024 JAMA Netw Open.
- Classical Conditioning Fails to Elicit Allodynia in an Experimental Study with Healthy Humans. Madden 2017 Pain Med.
- Topical glyceryl trinitrate (GTN) and eccentric exercises in the treatment of mid-portion achilles tendinopathy (the NEAT trial): a randomised double-blind placebo-controlled trial. Kirwan 2024 Br J Sports Med.
- Placebo analgesia in physical and psychological interventions: Systematic review and meta-analysis of three-armed trials. Hohenschurz-Schmidt 2024 Eur J Pain.