Published online May 14, 2021. doi: 10.3748/wjg.v27.i18.2219
Peer-review started: January 25, 2021
First decision: February 27, 2021
Revised: March 13, 2021
Accepted: April 22, 2021
Article in press: April 22, 2021
Published online: May 14, 2021
Irritable bowel syndrome (IBS) is a common chronic disorder, where intestinal microbiota plays a pivotal role in its pathophysiology. Faecal microbiota transplantation for IBS appears to be a promising treatment of IBS.
In Western countries, there is a female predominance in IBS with female:male ratio of 2:1. In a recent randomized double-blind placebo-controlled trial on faecal microbiota transplantation (FMT) in IBS females responded better to FMT than did males.
We aimed to investigate whether there is a sex difference in the response to FMT in terms of symptoms, dysbiosis, and bacteria and short-chain fatty acids (SCFAs) profiles in the same cohort of patients that we had investigated in our previous randomized controlled trial.
This study included 164 patients who fulfilled the Rome IV criteria for the diagnosis of IBS. These patient’s cohort included IBS diarrhoea-predominant (IBS-D), IBS-constipation predominant (IBS-C) and mixed diarrhoea and constipation (IBS-M) subtypes. They were randomized to placebo (own faeces), 30 g or 60 g donor’s faeces at a ratio of 1:1:1. The faecal transplant was administered via gastroscope to the duodenum. Patients completed IBS severity scoring system (IBS-SSS), the Fatigue Assessment Scale (FAS) and the IBS quality of life scale (IBS-QoL) questionnaires at the baseline and 2 wk, 1 mo and 3 mo after FMT. They also provided faecal samples at the baseline and 1 mo after FMT. Response was defined as a decrease of ≥ 50 points in the IBS-SSS total score after FMT. The faecal bacteria profile and dysbiosis were determined by the GA-map Dysbiosis Test (Genetic Analysis, Oslo, Norway) using the 16S rRNA gene. The levels of faecal SCFAs were determined by gas chromatography.
There was no sex difference in the response to FMT either in the placebo group or active treated group. There was no difference between females and males in either the placebo group or actively treated groups in the total score on the IBS-SSS, FAS or IBS-QoL, in dysbiosis, or in the faecal bacteria or SCFA level. However, the response rate was significantly higher in females with IBS-D than that of males at 1 mo, and 3 mo after FMT. Moreover, IBS-SSS total score was significantly lower in female patients with IBS-D than that of male patients both 1 mo and 3 mo after FMT.
There is no sex difference in the response to FMT in IBS patients with moderate-to-severe IBS symptoms belonging to the three of IBS subtypes of IBS-C and IBS-M in patients who did not responded to National Institute for Health and Care Excellence-modified diet. However, female patients with IBS-D had a significant higher response rate to FMT and lower IBS-SSS score after FMT than males.
The present observation that female patients with IBS-D respond better to FMT than males raise several questions as to the cause of this difference. Further studies are needed to explore the difference in diet and life style between females and males as possible causes for this difference.