Faecal transplant did not help irritable bowel syndrome

Design

Phase 3, randomised, double-blind, placebo-controlled; single rectal enema

Population

448 analysed adults with moderate-to-severe IBS (Rome IV), median age 36

Primary outcome

Proportion with a 75-point or greater IBS-SSS fall at 90 days

Effect

40% vs 38% responders; absolute difference 1.9 points (95% CI -8.1 to 12.0; p=0.76)

REFIT2, a double-blind phase 3 trial at five Norwegian hospitals, randomised 450 adults with moderate-to-severe IBS (Rome IV, IBS-SSS of 175 or higher) 2:1 to a single rectal enema of donor faecal microbiota or their own stool as placebo, with the response (a 75-point or greater fall in IBS-SSS at 90 days) as the primary endpoint.

Response occurred in 40% of the donor group and 38% of the placebo group, an absolute difference of 1.9 percentage points (95% CI -8.1 to 12.0; p=0.76). Adverse events were similar between groups.

This is a clean negative result from a well-sized, properly blinded trial, and it matters because patients increasingly ask about faecal transplant for IBS. The authors conclude that altering the microbiota alone is probably not enough to improve symptoms. It does not bear on faecal transplant for recurrent Clostridioides difficile, where the evidence is firmly positive.

• A single donor faecal transplant gave no benefit over placebo in moderate-to-severe IBS.
• Responders were 40% versus 38%, a difference of 1.9 points with a confidence interval spanning zero.
• The trial was double-blind, used autologous stool as placebo, and was adequately sized.
• Use this to counsel patients asking about faecal transplant for IBS.
• It does not change the positive evidence for faecal transplant in recurrent C. difficile.

Why it matters

It answers a question patients increasingly raise and closes off an unproven, invasive option.

Don't overread it

This concerns IBS only; it says nothing about faecal transplant for recurrent C. difficile infection.

The statistics, in plain English

A 1.9-point difference with a confidence interval from -8.1 to +12.0 and p=0.76 is a clear null: the data are consistent with no effect in either direction.

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