Spotlight on IBS interventions

Three potential treatments for irritable bowel syndrome (IBS) were assessed by recent systematic reviews and meta-analyses.

One meta-analysis, published in the June issue of The Lancet Gastroenterology & Hepatology, included 28 trials of gut-brain neuromodulators, with 2,475 adult IBS patients; 10 of the trials were new since the authors' previous meta-analysis. The relative risk of global IBS symptoms failing to improve was lower with the neuromodulators than with placebo (relative risk [RR] in 22 trials, 0.77; 95% CI, 0.69 to 0.87). Tricyclic antidepressants had the best evidence of an effect on overall symptoms (RR, 0.70; 95% CI, 0.62 to 0.80) and abdominal pain specifically (RR, 0.69; 95% CI, 0.54 to 0.87). For abdominal pain, there was evidence supporting selective serotonin reuptake inhibitors (SSRIs) (RR in seven trials, 0.74; 95% CI, 0.56 to 0.99) and serotonin and norepinephrine reuptake inhibitors (RR in two trials, 0.22; 95% CI, 0.08 to 0.59). “The findings support guidelines that recommend use of tricyclic antidepressants for ongoing global symptoms or abdominal pain but also highlight a potential for SSRIs to be modestly effective for abdominal pain,” said the study authors.

An accompanying editorial agreed that the results support gut-brain neuromodulators' “beneficial effects on IBS symptoms, although further work is needed to finetune the selection of those patients who would benefit from them the most.” The editorial also said that referring to the drugs as gut-brain neuromodulators is “essential, because antidepressants might evoke negative feelings by patients and can be perceived as stigmatizing.” A clear explanation of the drugs' effects on IBS can make patients more willing to take them, the editorial noted.

A second meta-analysis, also published in the June issue of The Lancet Gastroenterology & Hepatology, looked at 28 trials of 11 different active dietary interventions for IBS, with a total of 2,338 patients. It found that a diet with reduced starch and sucrose ranked first overall (RR of global IBS symptoms not improving, 0.41; 95% CI, 0.26 to 0.67) and a diet low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAP) ranked fourth (RR, 0.51; 95% CI, 0.37 to 0.70). For abdominal bloating or distension, only a low FODMAP diet was superior to usual diet (RR, 0.55; 95% CI, 0.37 to 0.80). None of the dietary interventions beat a usual diet for improving bowel habits. “Overall, although some of the dietary interventions studied more recently, including a starch-reduced and sucrose-reduced diet, a gluten-free diet, a tritordeum-based diet, and a FODMAP-simple diet, were ranked highly in the network in some analyses, these were studied in only one or two trials comprising small numbers of patients, and their findings should therefore be viewed as preliminary, rather than confirmatory. Larger, definitive trials of these interventions are needed,” said the review authors.

An accompanying editorial said that “the expanding range of diet-based treatments is encouraging” and noted that “given the variability in IBS pathophysiology that can exist across patients, different diets could provide different benefits, and offering multiple evidence-based options might prove valuable.”

These two reviews were published early online to mark IBS Awareness Month in April, noted an additional accompanying editorial, which called for more research on the condition. “Collaboration between all parties, including patients, the health-care and research communities, funders, and industry, will be required to break the current cycle of underfunding and limited progress and to improve the lives of those living with IBS,” the editorial said.

Finally, a meta-analysis published by the American Journal of Gastroenterology on May 13 assessed evidence on the therapeutic effect of yoga on IBS symptoms. A total of 11 trials with 535 patients were evaluated, seven of which included adults. The yoga interventions varied in length from six weeks to eight months, but overall, there was no difference between yoga and control groups in effects on severity of GI symptoms, anxiety, depression, or quality of life. The authors concluded that yoga “cannot be recommended as a treatment for IBS” until large-scale randomized controlled trials fill the current evidence gaps.