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9th May 2022
The use of a fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAP) diet has been shown in a randomised controlled trial to provide much better relief of irritable bowel syndrome (IBS) symptoms compared with using a musculotropic spasmolytic agent. This was the main result from a study by researchers at the department of Gastroenterology and Hepatology, KU Leuven University Hospitals Leuven, Belgium.
Irritable bowel syndrome has been defined as a functional bowel disorder in which recurrent abdominal pain is associated with defecation or a change in bowel habits. It is a common condition and in one 2020 review, the pooled IBS prevalence among studies that used the Rome IV criteria was 3·8%. Several treatment options are available for the management of IBS and a 2008 systemic review and meta-analysis concluded that fibre, anti-spasmodics (musculotropic spasmolytics) and peppermint oil were all more effective than placebo in the treatment of IBS. One particular spasmolytic agent is otilonium bromide (OB) which acts as an L-type calcium channel antagonist in intestinal and colonic smooth muscle cells. OB has been found to be more effective than placebo in IBS with a significant therapeutic benefit after 10 weeks and which is maximal after 15 weeks. In recent years however, the use of a FODMAP diet has been found to be effective at reducing functional gastrointestinal symptoms in patients with IBS. Nevertheless, there is uncertainty over whether or not a FODMAP diet provides superior symptomatic relief for patients with IBS compared to the use OB.
For the current trial, the Belgium team randomised newly treated patients with IBS to either OB 40mg three-times daily or a FODMAP diet and which was made available via a smartphone app and for those without access to a suitable electronic device, the diet instructions were available as a booklet. The diet itself was not a strict low FODMAP diet, but rather designed as a FODMAP-lowering diet. Consequently, small amount of FODMAPs were allowed, but the app did provide advice on which foods should be avoided or be reduced and offered suitable alternatives. Patients self-completed several questionnaires, one of which was the IBS symptom Severity scale (IBS-SSS) and this used for the primary outcome, with a responder defined as a patient who improved by ≥50 points on the IBS-SSS compared with baseline after 8 weeks.
FODMAP and improvement in IBS symptom scores
A total of 459 patients were randomised to OB (232) or a FODMAP diet. The mean age of participants randomised to OB was 41.2 years (76% female) which was slightly higher than the mean age of those assigned to the diet (40.6 years). The mean baseline IBS-SSS score was the same (267) in both groups.
After 8 weeks, a significantly higher proportion of participants using the FODMAP diet arm achieved the primary outcome (71% vs 61%, diet vs OD, p = 0.03). In fact, this difference became significant after only 4 weeks (62% vs 51%, diet vs OB, p = 0.02). Numerically, FODMAP diet participants saw a change from baseline in their IBS-SSS score of -97.42 after 8 weeks whereas the OB experienced a smaller mean reduction of only -76.91.
The authors concluded that the FODMAP diet was superior to standard medical therapy and suggested that this simple dietary approach should be considered as a first-line therapy for patients with IBS.
Carbone F et al. Diet or medication in primary care patients with IBS: the DOMINO study – a randomised trial supported by the Belgian Health Care Knowledge Centre (KCE Trials Programme) and the Rome Foundation Research Institute Gut 2022
6th July 2021
The British Society of Gastroenterology (BSG) has revised its 2007 guidelines on the management of irritable bowel syndrome (IBS). The latest guidance covers all aspects of the condition ranging from initial assessment and management through to secondary care referral and any subsequent investigations that should be undertaken within that setting. The guideline makes reference to the revised diagnostic Rome IV criteria produced in 2016 and notes that while the criteria are an improvement on the earlier Rome III, the revision is perhaps more restrictive and calls into question whether these latest changes can be used to diagnose irritable bowel syndrome. The BSG therefore suggests that a more pragmatic definition of the condition is provided by NICE which states that the diagnosis should be considered only if the person has abdominal pain or discomfort that is either relieved by defecation or associated with altered bowel frequency or stool form. Furthermore, the BSG guidance recommends that all patients with IBS symptoms should have a full blood count, C-reactive protein or erythrocyte sedimentation rate, coeliac serology and that clinicians should discuss the underlying diagnosis, its causes and natural history to the patients. The guidance, while accepting a limited evidence-base, advises that all patients should take regular exercise and that soluble fibre is an effective treatment for global symptoms and abdominal pain. In contrast, it recommends against the use of insoluble fibre (e.g., wheat bran) as this might exacerbate symptoms.
Medical treatments endorsed for irritable bowel syndrome include loperamide, especially where IBS is associated with diarrhoea, antispasmodics and peppermint oil and polyethylene glycol for associated constipation. Where there is uncertainty over the diagnosis or if symptoms are refractory, a referral should be made to secondary care. Several second-line therapies including tricyclic antidepressants, selective serotonin re-uptake inhibitors, linaclotide, lubiprostone and plecanatide. There is also a discussion of new and emerging treatments together with a recognition of the value of cognitive behavioural therapy, gut-directed hypnotherapy and general psychological therapies.
One area new to the guideline is the acknowledgement of a potential pathological role of an altered microbiome and which has led to interest in the use of probiotics as a potential treatment for IBS. For the guideline, the authors updated a 2018 meta-analysis on the efficacy of probiotics and found that compared to placebo, a combination of probiotics, had a significant effect on global symptoms or abdominal pain (relative risk, RR = 0.79, 95% CI 0.70–0.89). This effect was also significant for individual species including lactobacillus, Bifidobacterium and Escherichia. Based on these data, the guidance recommended that patients wishing to use probiotics should take them for up to 3 months to assess the potential benefit.
The guideline concludes that irritable bowel syndrome is a multifactorial disorder that requires a positive diagnosis and the implementation of both non- and pharmacological therapy to improve symptoms and quality of life.
Vasant DH et al. British Society of Gastroenterology guidelines on the management of irritable bowel syndrome. BMJ 2021