Gut dysbiosis in patients with chronic pain: a systematic review and meta-analysis.

Introduction: Recent evidence supports the contribution of gut microbiota dysbiosis to the pathophysiology of rheumatic diseases, neuropathic pain, and neurodegenerative disorders. The bidirectional gut-brain communication network and the occurrence of chronic pain both involve contributions of the autonomic nervous system and the hypothalamic pituitary adrenal axis. Nevertheless, the current understanding of the association between gut microbiota and chronic pain is still not clear. Therefore, the aim of this study is to systematically evaluate the existing knowledge about gut microbiota alterations in chronic pain conditions.
Methods: Four databases were consulted for this systematic literature review: PubMed, Web of Science, Scopus, and Embase. The Newcastle-Ottawa Scale was used to assess the risk of bias. The study protocol was prospectively registered at the International prospective register of systematic reviews (PROSPERO, CRD42023430115). Alpha-diversity, β-diversity, and relative abundance at different taxonomic levels were summarized qualitatively, and quantitatively if possible.
Results: The initial database search identified a total of 3544 unique studies, of which 21 studies were eventually included in the systematic review and 11 in the meta-analysis. Decreases in alpha-diversity were revealed in chronic pain patients compared to controls for several metrics: observed species (SMD= -0.201, 95% CI from -0.04 to -0.36, p=0.01), Shannon index (SMD= -0.27, 95% CI from -0.11 to -0.43, p<0.001), and faith phylogenetic diversity (SMD -0.35, 95% CI from -0.08 to -0.61, p=0.01). Inconsistent results were revealed for beta-diversity. A decrease in the relative abundance of the Lachnospiraceae family, genus Faecalibacterium and Roseburia , and species of Faecalibacterium prausnitzii and Odoribacter splanchnicus , as well as an increase in Eggerthella spp., was revealed in chronic pain patients compared to controls.
Discussion: Indications for gut microbiota dysbiosis were revealed in chronic pain patients, with non-specific disease alterations of microbes.
Systematic Review Registration: https://www.crd.york.ac.uk/prospero/, identifier CRD42023430115.
Competing Interests: LG is a postdoctoral research fellow funded by the Research Foundation Flanders FWO, Belgium project number 12ZF622N. JP received grant support from Medtronic, Boston Scientific, Abbott, NIH 2R01CA166379-06, NIH R01EB030324, NIH Blueprint 3U54EB015408 and NIH U44NS115111. She is part of the Board of Directors of Facial Pain Association, Board of Directors at Large of International Neuromodulation Society, President Elect of American Society of Stereotactic and Functional Neurosurgery and President of North American Neuromodulation Society. PR reports grants from Medtronic, Abbott and Boston Scientific and consultant fees and payments for lectures from Medtronic and Boston Scientific, outside the submitted work. MM has received speaker fees from Medtronic, Saluda and Nevro. STIMULUS received independent research grants from Medtronic. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
(Copyright © 2024 Goudman, Demuyser, Pilitsis, Billot, Roulaud, Rigoard and Moens.)