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The long-term efficacy and possible adverse events of fecal microbiota transplantation (FMT) for irritable bowel syndrome (IBS) are unknown, and follow-up in previous studies has been no more than 1 year. To examine the longer-term consequences of FMT, Magdy El-Salhy, MD, PhD, of Stord Helse-Fonna Hospital in Stord, Norway, and colleagues conducted a 3-year follow-up of patients in their previous .

El-Salhy discussed the follow-up findings -- recently published in -- in the following interview with the Reading Room.

What had earlier studies of FMT for IBS shown?

El-Salhy: FMT has been applied to IBS patients in six randomized trials. In three of these, FMT reduced symptoms and improved the quality of life of IBS patients, while no effects were found in the other three. It is difficult to compare these studies, however, owing to variations in the criteria used to select the donors and patients, the dose and handling of the fecal transplant, and the route by which the transplant was administrated. Furthermore, different measurements were used to assess the efficacy of FMT.

What questions did your original study set out to answer?

El-Salhy: Is FMT effective in treating IBS symptoms and associated chronic fatigue and are its effects durable in the long run? In addition, is there a dose-dependent effect on the outcome?

Other questions were: what changes occurred in the intestinal bacterial profile and in microbiota dysbiosis following FMT, and which bacteria were associated with IBS symptoms and fatigue?

Furthermore, does FMT induce long-term intestinal colonization of beneficial bacteria and reduction in harmful bacteria, and is the procedure associated with short- and long-term adverse events?

What was the composition of the study cohort?

El-Salhy: Two hundred patients who fulfilled the Rome IV criteria for the diagnosis of IBS (including IBS-diarrhea, IBS-constipation, and IBS-mixed) without red flags were assessed for eligibility, and 165 patients completed the study. All had a long duration of IBS symptoms and a symptom onset that was not associated with any gastrointestinal or other infections. A medical history was taken for all patients, and they underwent a complete physical examination, as well as laboratory tests, gastroscopy, colonoscopy, and biopsy, to exclude other diseases.

All patients adhered to a modified National Institute for Health and Care Excellence (U.K.) diet.

What were the main findings of the two studies?

El-Salhy: At 3 months following FMT, about 89% of the patients who received 60 g and 77% of those who received 30 g of transplant responded to FMT, regardless of their IBS subtype. The corresponding response in the placebo group was about 24%. Three years after FMT, 72% of the patients who received a 60-g transplant and 65% of patients who received a 30-g transplant maintained response to FMT. The response of the placebo group 3 years after FMT was 27%. The majority (80%) of patients who relapsed at 3 years responded to retransplantation.

Of note, patients who responded to FMT had significantly fewer IBS symptoms and fatigue and a greater quality of life for up to 3 years after FMT.

In other findings, the intestinal bacterial profile changed after FMT, and long-term colonization of beneficial bacteria was established. The dysbiosis index decreased in the FMT treatment groups at 3 years after FMT, but not in the placebo group.

Fluorescent signals of 10 bacteria had significant correlations with IBS symptoms and fatigue after FMT in both FMT dosage groups.

Adverse events were mild and self-limiting and only occurred during the first few days after FMT. No long-term adverse events were recorded.

Were there any notable patient characteristics associated with superior response?

El-Salhy: All IBS patients benefited from FMT. However, those with severe IBS (IBS Symptom Severity Score [SSS] total of ≥300) responded better than those with moderate symptoms (IBS-SSS total of ≥175), and female patients responded better to FMT than males.

What are the clinical implications of your results?

El-Salhy: The present results are based on an easy-to-perform, safe, and effective protocol for treating IBS and associated chronic fatigue. The effect of FMT performed with our protocol is maintained for up to 3 years in the majority of patients. FMT induces long-term colonization of beneficial intestinal bacteria and is a safe intervention over the longer term.

You can read the abstract of the study here, and about the clinical implications of the study here.