Four things, tested in this group

When a treatment is described as working for irritable bowel syndrome, it is fair to ask who it was tested on. For symptoms that persist while inflammatory bowel disease is in remission, the review counts four interventions that have been tested in randomised controlled trials in that population specifically:

• gut-directed psychological therapy
• the low-FODMAP diet
• probiotics
• ramosetron, a drug licensed in some countries for diarrhoea-predominant irritable bowel syndrome

Everything else in the toolkit — antispasmodics, antidiarrhoeals, laxatives, neuromodulators, exercise — has been tested in irritable bowel syndrome without inflammatory bowel disease, and the results are being carried across. The review is comfortable with that, and says so: there is no compelling evidence that irritable bowel syndrome in quiescent inflammatory bowel disease should be managed any differently, so the general principles apply. Carried across is still worth knowing, though, because it is the difference between evidence about people like you and evidence about people somewhat like you.

Pain, and how little is settled

At least one in four people with quiescent inflammatory bowel disease report chronic abdominal pain, and 42 percent of people with the disease say they would definitely like help with pain. It is more common in Crohn’s disease — 31.2 percent report mild pain and 15.5 percent moderate or severe — than in ulcerative colitis, at 23.4 and 10.1 percent.

Against that, Cochrane reviews find very low certainty of evidence for both drug and non-drug treatments of abdominal pain in Crohn’s disease and ulcerative colitis. That grading is the finding, not a hedge: the honest summary is that a common problem has been studied less well than its frequency deserves.

What the individual pieces look like

• The low-FODMAP diet has the most robust evidence base among diets for irritable bowel syndrome, and two prospective studies confirm it in quiescent inflammatory bowel disease. The review says it should be followed under a registered dietitian, and gives a reason: around 20 percent of people with inflammatory bowel disease screen positive for avoidant–restrictive food intake disorder.
• Low-dose tricyclic antidepressants, used here as neuromodulators rather than for mood, improve outcomes in irritable bowel syndrome across 28 randomised trials, and produced moderate improvement in global well-being in quiescent inflammatory bowel disease, with more benefit in ulcerative colitis than in Crohn’s disease.
• Antispasmodics such as peppermint oil rest on very low quality evidence, and indirect comparisons suggest they are less effective than the tricyclics.
• Opioids are discouraged. There is no evidence they improve abdominal pain or quality of life in Crohn’s disease, and they can trigger or worsen other gut–brain disorders.

Mood belongs in this, carefully

Up to a third of people with inflammatory bowel disease are affected by anxiety and around a quarter by depression, and a history of mood disorder is the strongest single predictor of irritable bowel syndrome type symptoms in ulcerative colitis — a hazard ratio of 5.2, with a 95 percent confidence interval of 2.2 to 12.3. The same association is not seen in Crohn’s disease.

That is an association measured in a population, and it cuts in a direction people rarely expect. The review notes that the questionnaires used to score disease activity are themselves influenced by depression: people with more severe depressive symptoms are more likely to be classified as having active disease. Mood changes the reading on the instrument, which is an argument for better instruments, not for taking the symptoms less seriously.