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

Florencia Carbone 1 2, Karen Van den Houte 2, Linde Besard 1, Céline Tack 1, Joris Arts 1 3, Philip Caenepeel 1 3, Hubert Piessevaux 4, Alain Vandenberghe 5, Christophe Matthys 6, Jessica Biesiekierski 2 7, Luc Capiau 8, Steven Ceulemans 8, Olivier Gernay 8, Lydia Jones 8, Sophie Maes 8, Christian Peetermans 8, Willem Raat 9, Jeroen Stubbe 8, Rudy Van Boxstael 8, Olivia Vandeput 8, Sophie Van Steenbergen 8, Lukas Van Oudenhove 2, Tim Vanuytsel 1 2, Michael Jones 10, Jan Tack 11 2 12 13, DOMINO Study Collaborators; Domino Study Collaborators
Collaborators, Affiliations 
PMID: 35483886 PMCID: PMC9554021 DOI: 10.1136/gutjnl-2021-325821
Free PMC article

Abstract
Background: In Europe, IBS is commonly treated with musculotropic spasmolytics (eg, otilonium bromide, OB). In tertiary care, a low fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAP) diet provides significant improvement. Yet, dietary treatment remains to be explored in primary care. We evaluated the effect of a smartphone FODMAP-lowering diet application versus OB on symptoms in primary care IBS.

Methods: IBS patients, recruited by primary care physicians, were randomised to 8 weeks of OB (40 mg three times a day) or diet and followed for 24 weeks. We compared IBS Symptom Severity Score and the proportion of responders (improvement ≥50 points) in all patients and the subgroup fulfilling Rome IV criteria (Rome+). We also evaluated treatment efficacy, quality of life, anxiety, depression, somatic symptom severity (Patient Health Questionnaire (PHQ15, PHQ9)) and treatment adherence and analysed predictors of response.

Results: 459 primary care IBS patients (41±15 years, 76% female, 70% Rome+) were randomised. The responder rate after 8 weeks was significantly higher with diet compared with OB (71% (155/218) vs 61% (133/217), p=0.03) and more pronounced in Rome+ (77% (118/153) vs 62% (98/158), p=0.004). Patients allocated to diet (199/212) were 94% adherent compared with 73% with OB (148/202) (p<0.001). The significantly higher response rate with diet was already observed after 4 weeks (62% (132/213) vs 51% (110/215), p=0.02) and a high symptom response persisted during follow-up. Predictors of response were female gender (OR=2.08, p=0.04) for diet and PHQ15 (OR=1.10, p=0.02) for OB.

Conclusion: In primary care IBS patients, a FODMAP-lowering diet application was superior to a spasmolytic agent in improving IBS symptoms. A FODMAP-lowering diet should be considered the first-line treatment for IBS in primary care.