Systematic review: the prevalence of idiopathic bile acid malabsorption as diagnosed by SeHCAT scanning in patients with diarrhoea-predominant irritable bowel syndrome

P>Background Recurrent, watery diarrhoea affects one-third of patients diagnosed with irritable bowel syndrome ('IBS-D'). Idiopathic bile acid malabsorption ('I-BAM') may be the cause. Aim To determine the prevalence of I-BAM in patients suffering from IBS-D. Methods A systematic search was performed of publications reporting patients presenting with IBS-D type symptoms, who were subsequently confirmed as having I-BAM by SeHCAT scanning. Results Eighteen relevant studies, 15 prospective, comprising 1223 patients were identified. Five studies (429 patients) indicated that 10% (CI: 7-13) patients had severe bile acid malabsorption (SeHCAT 7 day retention < 5% of baseline value). 17 studies (1073 patients) indicated that 32% (CI: 29-35) patients had moderate bile acid malabsorption (SeHCAT < 10%). 7 studies (618 patients) indicated that 26% (CI: 23-30) patients had mild (SeHCAT < 15%) bile acid malabsorption. Pooled data from 15 studies showed a dose-response relationship according to severity of malabsorption to treatment with a bile acid binder: response to colestyramine occurred in 96% of patients with < 5% retention, 80% at < 10% retention and 70% at < 15% retention. Conclusions Idiopathic adult-onset bile acid malabsorption is not rare. International guidelines for the management of irritable bowel syndrome need to be revised so that clinicians become more aware of this possibility.