Fecal microbiota transplantation for the treatment of irritable bowel syndrome: A systematic review and meta-analysis

Table 1 Characteristics of randomised controlled trials of faecal microbiota transplantation for treating irritable bowel syndrome

Ref.	Trial design	Country	Sample size	IBS subtypes	Inclusion criteria	Frequency and route of administration	FMT-content	Placebo content	Pretreatment	Number of donors
Aroniadis et al[59], 2019	RCT, crossover	United States	48 (25 FMT vs 23 placebo)	IBS-D	Moderate-to-severe IBS symptoms (IBS-SSS > 175)	3 d of 25 oral capsules	3 × 25 frozen capsules (0.38 g donor stool/capsule) (Openbiome)	Non-toxic brown pigment	PPI for three days	One donor for one patient (four different donors)
El-Salhy et al[60], 2020	RCT, 3 parallel groups	Norway	164 (54/30 gram FMT, 55/60 gram FMT, 55 placebo)	All subtypes	Moderate-to-severe IBS symptoms (IBS-SSS > 175)	Single treatment via gastroscope to distal duodenum	Once 30 g or 60 gram of frozen feces in sterile saline solution	Autologous faeces	None	One donor
Halkjær et al[43], 2018	RCT, 2 parallel groups	Denmark	51 (25 FMT, 26 placebo)	All subtypes	Moderate-to-severe IBS symptoms (IBS-SSS > 175)	12 d of 25 oral capsules	25 FMT capsules (one daily dose containing approximately 12 g frozen faecal material)	Saline, glycerol and food colouring E150	Bowel cleansing	Donor mix from four donors
Holster et al[61], 2019	RCT, 2 parallel groups	Sweden	16 (8 FMT, 8 placebo)	All subtypes	IBS with small amounts of butyrate-producing bacteria	Single treatment via colonoscopy to the caecum	30 g frozen stool in sterile saline and glycerol	Autologous feces	Bowel cleansing and 4 mg loperamide	Two donors (three patients received stool from donor 1, the remaining five from donor 2)
Holvoet et al[44], 2021	RCT, 2 parallel groups	Belgium	62 (43 FMT, 19 placebo)	IBS-D and IBS-M	Refractory IBS with failure of at least three conventional IBS therapies	Single treatment via nasojejunal administration	Fresh feces mixed with saline	Autologous feces	Bowel cleansing	Two donors
Johnsen et al[62], 2018	RCT, 3 parallel groups	Norway	83 (26 fresh FMT, 29 frozen FMT, 28 placebo)	IBS-D and IBS-M	Moderate-to-severe IBS symptoms (IBS-SSS > 175)	Single treatment administered into the caecum via colonoscopy	50–80 g fresh or frozen feces mixed with saline and glycerol	Autologous feces	Bowel cleansing and 8 mg loperamid	Donor mix from two donors
Lahtinen et al[58], 2020	RCT, 2 parallel groups	Finland	51 (25 FMT, 26 placebo)	IBS-D, IBS-M and IBS-U	Patients who remained symptomatic despite receiving conventional treatment	Single treatment administered into the caecum via colonoscopy	30 g frozen suspension	Autologous feces	Bowel cleansing	One donor
Singh et al[63], 2022	RCT, 4 parallel groups	United States	23 (11 FMT, 12 placebo)	IBS-D	IBS-SSS > 150 or > 175	Single treatment with 19 oral capsules	Capsule contain 0.75 frozen fecal filtrate) (Openbiome)	Glycerol with brown coloring agent	Bowel cleansing	Six donors (unknown if donors were mixed)

FMT: Fecal microbiota transplantation; IBS: Irritable bowel syndrome; IBS-C: Constipation-predominant irritable bowel syndrome; IBS-D: Diarrhoea-predominant irritable bowel syndrome; IBS-M: Mixed irritable bowel syndrome; IBS-U: Unclassified irritable bowel syndrome; RCT: Randomised controlled trials; PPI: Proton pump inhibitors.