Small intestinal bacterial overgrowth is associated with clinical relapse in patients with quiescent Crohn’s disease: a retrospective cohort study

BACKGROUND: Crohn’s disease (CD) is an irreversible inflammatory disorder, characterized by alternating periods of relapse and remission. It is particularly important to predict clinical relapses in patients with CD because patients in remission could relapse frequently in a randomized way. Small intestinal bacterial overgrowth (SIBO) is a symptom of gut microbial dysbiosis and is commonly observed in patients with CD, which may affect disease course. The present research was carried out to establish whether SIBO is linked to the subsequent clinical relapse of CD. METHODS: This retrospective observational cohort research included consecutive patients (≥18 years) with quiescent CD who underwent lactulose hydrogen-methane breath test to diagnose SIBO managed at Jinling Hospital in China from January 2016 to June 2020. We assessed demographic data, laboratory parameters, SIBO and clinical characteristics including disease location and behavior, surgical history and current and previous medication at baseline and analyzed these data to identify factors associated with clinical relapse. Patients were followed up for 18 months and assessed for the Crohn’s Disease Activity Index (CDAI) scores, treatment escalation, and disease progression to determine the primary endpoint of clinical relapse. RESULTS: Of the 73 enrolled patients, 34 (46.6%) were positive for SIBO. Twenty-seven (37.0%) patients experienced clinical relapse within 18 months (median time of relapse: 13.9 months). SIBO in the relapse group was considerably elevated compared to the non-relapse group (63.0% vs. 37.0%, P=0.032). The multivariate Cox regression analysis showed that SIBO [hazard ratio (HR) 2.79, P=0.017] and penetrating disease behavior (HR 3.66, P=0.040) were the sole individual risk elements for relapse in patients with quiescent CD. CONCLUSIONS: This study indicated that SIBO was highly prevalent in patients with CD, and was independently linked to clinical relapse in quiescent patients. Detecting SIBO may be a valuable option for the prognostic assessment of patients in clinical remission.