Fecal Microbiota Transplantation Reduces Symptoms in Some Patients With Irritable Bowel Syndrome With Predominant Abdominal Bloating: Short- and Long-term Results From a Placebo-Controlled Randomized Trial

Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder associated with intestinal dysbiosis. Given the reported promising results of open-label fecal microbiota transplantation (FMT) therapy in patients with predominant abdominal bloating, we studied efficacy of this treatment in a randomized, placebo-controlled trial. Patients with refractory IBS, defined as failure of ≥3 conventional therapies, were randomly assigned to single-dose nasojejunal administration of donor stools (n = 43) or autologous stools (n = 19) in a double-blind study, performed from December 2015 through October 2017, and were followed up for 1 year. IBS-related symptoms were assessed by using a daily symptom diary to determine general abdominal discomfort, abdominal bloating, abdominal pain, and flatulence on a scale of 1–6. Number of daily bowel movements, consistency of the stools, and abdominal circumference were also recorded. Patients completed the IBS-specific quality of life questionnaire. Primary endpoints were improvement of IBS symptoms and bloating at 12 weeks (response). Secondary endpoints were changes in IBS symptom scores and quality of life. Stool samples were collected for microbiota amplicon sequencing. Open-label retransplantation was offered after the trial. At week 12, 56% of patients given donor stool reported improvement in both primary endpoints compared with 26% of patients given placebo (P = .03). Patients given donor stool had significant improvements in level of discomfort (mean reduction, 19%; median score before FMT, 3.98; range, 2.13–6.00; median score after FMT, 3.1; range, 951.29–5.90), stool frequency (mean reduction, 13%; median score before FMT, 2.10; range, 0.57–14.29; median score after FMT 1.7; range, 0.71–4.29), urgency (mean reduction, 38%; median score before FMT, 0.61; range, 0.00–1.00; median score after FMT, 0.37; range, 0.00–1.00), abdominal pain (mean reduction, 26%; median score before FMT, 3.88; range, 1.57–5.17; median score after FMT, 2.80; range, 1.14–4.94), flatulence (mean reduction, 10%; median score before FMT, 3.42; range, 0.71–6.00; median score after FMT, 3.07; range, 0.79–4.23), and quality of life (mean increase, 16%; median score before FMT 32.6; range, 11–119; median score after FMT, 43.1; range, 32.25–99). A significantly higher proportion of women given donor stool (69%) had a response than men (29%) (P = .01). Fecal samples from responders had higher diversity of microbiomes before administration of do