or very low certainty, with many studies suffering from bias, according to a recent review and meta-analysis.
These shortcomings in the probiotic research landscape should be kept in mind when making treatment recommendations, reported researchers who were led by Alexander C. Ford, MBChB, of the Leeds Gastroenterology Institute, University of Leeds (England). They suggested these issues need to be addressed in the methodology of future clinical trials.
“Although multiple probiotics have been tested in IBS in randomized clinical trials, understanding of which probiotics may be beneficial is limited,” the investigators wrote in Gastroenterology.
They noted that previous efforts – including their own – to meta-analyze these findings have been hindered by a scarcity of trial data coupled with heterogeneity across probiotic strains, combinations, and doses, resulting in clinical uncertainty.
“Making recommendations concerning which probiotics, or combinations of probiotics, are beneficial according to IBS subtype or individual symptom has been difficult to date,” they wrote.
To narrow this knowledge gap, the researchers conducted an updated systematic review and meta-analysis with newly identified trials.
“There is continued interest in the role of probiotics in the management of IBS, as evidenced by the publication of more than 20 new randomized clinical trials since the prior version of this meta-analysis in 2018,” they wrote.
The new dataset included 82 RCTs comprising 10,332 patients with IBS. Along with safety, three separate efficacy endpoints were evaluated: global symptoms, abdominal pain, and abdominal bloating or distension.
For global symptoms, moderate-certainty evidence supported the efficacy of Escherichia coli strains; low-certainty data supported Lactobacillus plantarum 299V and other Lactobacillus strains; and very-low-certainty evidence supported Bacillus, LacClean Gold S, and Duolac 7s strains, and combination probiotics.
For abdominal pain, low-certainty evidence supported Bifidobacterium strains and Saccharomyces cerevisiae I-3856. Very-low-certainty data supported Lactobacillus, Saccharomyces, and Bacillus strains, and combination probiotics.
Very-low-certainty evidence supported the benefits of Bacillus strains and combination probiotics for alleviating abdominal bloating or distension.
In a safety analysis of 55 trials involving more than 7,000 patients, risk of adverse events was no higher for probiotics than placebo.
“Our analyses provide some support for the use of certain probiotics in IBS, and also for particular strains for specific symptoms,” the investigators wrote. “However, there is a paucity of data for their use in patients with IBS-C [IBS with constipation], with only seven RCTs reporting efficacy in this subtype, and no evidence of efficacy in any of these analyses. Their use in patients with IBS-C is, therefore, not supported by current evidence.”
A broader discussion in the publication called out the general lack of high certainty evidence in this area of clinical research.
“Only 24 of 82 eligible RCTs were low risk of bias across all domains, and there was significant heterogeneity between trials in many of our analyses, as well as evidence of publication bias, or other small study effects, in some of our analyses,” the researchers wrote. “The fact that few of the included studies were low risk of bias across all domains should be borne in mind when making treatment recommendations.”
The investigators disclosed relationships with Salix, Biocodex, 4D Pharma, and others.
