What is the aim of this review?
The aim of this Cochrane Review was to find out whether probiotics can induce remission in people with Crohn's disease. We analysed information from two studies to answer this question.
Key messages
It is unclear whether probiotics are better than placebo (dummy pill). No serious adverse events occurred in either study.
What was studied in the review?
Crohn's disease is a medical condition that causes inflammation of the bowels and can lead to symptoms of ulcers in the mouth, abdominal pain, diarrhoea, obstruction, fistulisation (tunnels between the bowels and nearby organs), abscesses, malnutrition, low haemoglobin (blood) levels, and fatigue. There is some evidence to suggest that an imbalance in the bacteria of the gut is a cause of the disease. Probiotics, which are live microorganisms, could alter the bacteria of the gut and possibly reduce inflammation.
What are the main results of the review?
We searched for randomised controlled trials (RCTs; clinical studies where people are randomly placed into one of two or more treatment groups) comparing probiotics with placebo. There were two RCTs, with information on 46 people. The trials looked at adults. It is unclear whether probiotics are different to placebo for inducing remission of Crohn's disease. It is unclear whether probiotics lead to a difference in adverse events (minor and serious) when compared with placebo.
Conclusion
This review found two studies that examined and showed no benefit of probiotics for the treatment of active Crohn's disease. Since the studies were very small, no definite conclusions can be made at this time. Probiotics were generally well tolerated; there was just one side effect leading to the stopping of treatment with probiotics, but details of this were not given. With the evidence presented in these studies, we are unable to make conclusions as to the effectiveness of probiotics. Better designed studies, with more participants, are needed.
How up-to-date is this review?
This review is up-to-date as of 6 July 2020.
The available evidence is very uncertain about the efficacy or safety of probiotics, when compared with placebo, for induction of remission in Crohn's disease. There is a lack of well-designed RCTs in this area and further research is needed.
Crohn's disease (CD) is a chronic inflammatory disorder of the gastrointestinal tract, in which the pathogenesis is believed to be partly influenced by the gut microbiome. Probiotics can be used to manipulate the microbiome and have therefore been considered as a potential therapy for CD. There is some evidence that probiotics benefit other gastrointestinal conditions, such as irritable bowel syndrome and ulcerative colitis, but their efficacy in CD is unclear. This is the first update of a Cochrane Review previously published in 2008.
To assess the efficacy and safety of probiotics for the induction of remission in CD.
The following electronic databases were searched: MEDLINE (from inception to 6 July 2020), Embase (from inception to 6 July 2020), the Cochrane Central Register of Controlled Trials (CENTRAL), The Cochrane IBD Review Group Specialised Trials Register, World Health Organization (WHO) International Clinical Trials Registry, and ClinicalTrials.gov.
Randomised controlled trials (RCTs) that compared probiotics with placebo or any other non-probiotic intervention for the induction of remission in CD were eligible for inclusion.
Two review authors independently extracted data and assessed the methodological quality of included studies. The primary outcome was clinical remission. Risk ratios (RRs) and 95% confidence intervals (CIs) were calculated for dichotomous outcomes.
There were two studies that met criteria for inclusion. One study from Germany had 11 adult participants with mild-to-moderate CD, who were treated with a one-week course of corticosteroids and antibiotics (ciprofloxacin 500 mg twice daily and metronidazole 250 mg three times a day), followed by randomised assignment to Lactobacillus rhamnosus strain GG (two billion colony-forming units per day) or corn starch placebo. The other study from the United Kingdom (UK) had 35 adult participants with active CD (CDAI score of 150 to 450) randomised to receive a synbiotic treatment (comprised of freeze-dried Bifidobacterium longum and a commercial product) or placebo. The overall risk of bias was low in one study, whereas the other study had unclear risk of bias in relation to random sequence generation, allocation concealment, and blinding. There was no evidence of a difference between the use of probiotics and placebo for the induction of remission in CD (RR 1.06; 95% CI 0.65 to 1.71; 2 studies, 46 participants) after six months. There was no difference in adverse events between probiotics and placebo (RR 2.55; 95% CI 0.11 to 58.60; 2 studies, 46 participants). The evidence for both outcomes was of very low certainty due to risk of bias and imprecision.