Frequent exposure to biologics is associated with small intestinal bacterial overgrowth in patients with Crohn’s disease: a retrospective case-control study

Background Small intestinal bacterial overgrowth (SIBO) is characterized by excessive bacteria in the small intestine, often accompanied by gastrointestinal symptoms. The advent of biologic therapies has significantly advanced the treatment of Crohn’s disease (CD), yet their influence on the development of SIBO remains unclear. Aims This study aims to elucidate the relationship between exposure to biologic therapies and the incidence of SIBO in CD patients. Methods This retrospective case-control study enrolled CD patients who underwent lactulose hydrogen-methane breath test (LHMBT) at Jinling Hospital from 2021 to 2024. Clinical data were collected and the risk factors for SIBO were identified using both univariate and multivariate logistic regression. Additionally, model validation was carried out using receiver operating characteristic (ROC) curve analysis, confusion matrix and 5-fold cross-validation. Results (1) Among the 86 CD patients enrolled, biologic administration differed significantly between the SIBO-positive ( n = 43) and SIBO-negative ( n = 43) group. (2) Identified risk factors for SIBO in CD patients included use of biologics in excess of five times compared to those with no biologic exposure ( OR = 4.541, P = 0.033), and intestinal stenosis ( OR = 3.262, P = 0.034). (3) ROC curve analysis was performed to evaluate the predictive value of the combined model that included biologic exposure frequency (≥5 times), body mass index (BMI), current steroid use, disease duration and intestinal stenosis, for predicting SIBO in CD patients (AUC = 0.778, P < 0.001). (4) The confusion matrix demonstrated an accuracy of 70.9% and a precision of 67.3%, while the 5-fold cross-validation verified that the predictive model achieved a mean AUC of 0.779 ± 0.03. Conclusions This study indicated that frequent exposure to biologics is associated with an increased presence of SIBO in CD patients, particularly in those with intestinal strictures.