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

Table 2 Summarised findings for comparing fecal microbiota transplantation with placebo for the treatment of irritable bowel syndrome

Outcomes and timeframe	Anticipated absolute effects		Relative effect (95%CI)	Number of participants (trials)	Certainty of the evidence (GRADE)	Comments
	Effect in placebo	Effect difference with FMT (95%CI)
Improvement of symptoms after three months	42 per 100	8 or more per 100 (from 13 or fewer to 46 or more)	RR 1.19 (0.68-2.10)	484 (8 RCTs)	++--1 Low	Improvement of symptoms as measured by a validated global IBS symptoms score (e.g., IBS-SSS scale from 0, no symptoms, to 500, maximum symptoms) (as defined by each trial)
Improvement of symptoms after six months	38 per 100	5 or fewer per 100 (from 25 or fewer to 52 or more)	RR 0.88 (0.33-2.39)	99 (3 RCTs)	++--2 Low	Improvement of symptoms as measured by a validated global IBS symptoms score (e.g., IBS-SSS scale from 0, no symptoms, to 500, maximum symptoms) (as defined by each trial)
Adverse events prior to end of trial	26 per 100	4 or more per 100 (from 10 or fewer to 30 or more)	RR 1.17 (0.63-2.15)	450 (7 RCTs)	++--3 Low	Common adverse events were mild and self-limiting gastrointestinal symptoms
Serious adverse events prior to end of trial	1 per 100	1 or fewer per 100 (from 1 or fewer to 2 or more)	RR 0.42 (0.07-2.60)	501 (8 RCTs)	++--4 Low	Serious adverse events included one suicide (placebo), cholecystitis (placebo), and one admission to the hospital due to discomfort after the FMT procedure
Dropouts due to adverse events prior to end of trial	1 per 100	1 or fewer per 100 (from 1 or fewer to 1 or more)	RR 0.24 (0.03-2.17)	502 (8 RCTs)	++--5 Low	Dropouts due to adverse events include one suicide (placebo) and one for discomfort after the FMT procedure (placebo)
Improvement in QoL scores after three months	NA	NA	MD -6.30 (-13.39 to 0.79)	406 (7 RCTs)	++--6 Low	Improvement of quality of life as measured by a validated scale IBS-QoL, where 34 items are summed and averaged for a total score and then transformed to a 0-100 scale for interpretation (high scores indicate better IBS-QoL)

¹Downgraded two levels due to considerable inconsistency (I² = 82%) and imprecision (267 events).

²Downgraded two levels due to moderate inconsistency (I² = 51%) and serious imprecision (34 events).

³Downgraded two levels due to substantial inconsistency (I² = 69%) and imprecision (142 events).

⁴Downgraded two levels due to serious imprecision (three events) and wide confidence interval.

⁵Downgraded two levels due to serious imprecision (two events) and wide confidence interval.

⁶Downgraded two levels due to moderate inconsistency (I² = 45%), heterogeneous method, and a small number of participants.

Patients or population: Participants diagnosed with irritable bowel syndrome according to a physician’s opinion or an accepted, symptom-based diagnostic criteria. Settings: Inpatient and outpatient. Intervention: Fecal microbiota transplantation. Comparison: Placebo (or autologous feces). FMT: Fecal microbiota transplantation; IBS: Irritable bowel syndrome; SSS: Symptom severity score; QOL: Quality of life measure; MD: mean difference; NA: Not available; RR: Risk ratio.