Martín Pérez 2024 — FMT in nociplastic pain: systematic review
One-paragraph summary
PRISMA-compliant systematic review (PROSPERO pre-registered, CRD42024611939) of 13 studies (n=409 subjects) evaluating fecal microbiota transplantation in nociplastic-pain conditions — fibromyalgia, IBS, chronic fatigue syndrome, and psoriatic arthritis. Key result: reductions in pain intensity, fatigue, and quality-of-life improvements, particularly in FM and IBS subgroups. CFS and psoriatic-arthritis outcomes were mixed, attributed to protocol heterogeneity (donor selection, route of administration, dosing) and patient-population differences. Adverse events were minimal. The review's central conclusion: FMT shows promise for nociplastic pain but requires standardized protocols and high-quality RCTs to confirm long-term efficacy. This is the first interventional-evidence paper supporting the B2 chain in FM patients — combined with Jakobsson 2026 (correlational) and Hanani 2026 (mechanistic), B2 now has correlational + mechanistic + interventional evidence and moves toward "closing".
Claims as triples
- gut_brain_axis_disruption — responds_to → fmt [evidence: 13-study systematic review, n=409, pain reduction esp. in FM and IBS; confidence: emerging]
- fmt — modulates → widespread_pain [evidence: review-tier consensus; confidence: emerging]
- fmt — modulates → fatigue [evidence: review-tier consensus; confidence: emerging]
Methods note
PRISMA-adherent systematic review. Databases: MEDLINE/PubMed, Scopus, EBSCOhost, Cochrane Library, Web of Science. Quality assessment: Cochrane RoB 2, ROBINS-I, NOS, CARE. Adult populations only. 13 included studies — clinical trials, case reports, retrospective analyses.
Limitations
- Preprint; not peer-reviewed at ingestion.
- Heterogeneity across the 13 included studies (different conditions, protocols, donors) limits meta-analytic interpretation.
- Many included studies are small (case reports, single-arm) — overall evidence quality is moderate at best.
- "FM-and-IBS" cluster benefit may be partly driven by IBS effects; FM-specific effect size needs stratified analysis.
- No biomarker stratification — the review doesn't address whether responders are anti-SGC-IgG positive.
Open questions raised
- Does FMT specifically reduce anti-SGC IgG titers? (None of the 13 included studies measured this — opportunity for next study; aligns with BASIS-FM stage-2 plans.)
- What's the optimal protocol (donor screening, dose, route, repeat dosing)?
- Are FM responders stratified by autoimmune subtype (anti-SGC IgG positive)?
- What's the durability of effect? (Studies vary widely on follow-up.)
Triangulation notes
- Strategically central for the BASIS-FM trial design — establishes that microbiome modulation does reduce FM symptoms in some patients, justifying the upstream-test stage 2 of the staged research program. The colesevelam first-stage tests the BA → IgG arrow with regulatory/practical advantages; this review supports moving to FMT in stage 2.
- Promotes B2 from "closing" toward closed: correlational (Jakobsson 2026) + mechanistic (Hanani 2026) + interventional (this review) evidence at every link.
- Connects to bridge B6 (post-infectious nociplastic conditions): if FMT works in FM and IBS but is mixed in CFS, mechanism subtypes within "nociplastic pain" matter — the bridge framework should differentiate these.