P420 Natural history of intra-abdominal inflammatory masses (phlegmons) in Crohn’s disease

Abstract

Abstract Background Intra-abdominal inflammatory masses (phlegmons) are a feature of penetrating Crohn’s disease (CD). However, there are few data on the natural history and outcomes of inflammatory masses in CD. We aimed to describe clinical outcomes and predictors of surgery in individuals with CD and intra-abdominal inflammatory masses (IAIM). Methods We conducted a multi-center retrospective cohort study. Patients with a diagnosis of CD or inflammatory bowel disease unclassified (IBD-U) and a finding of phlegmon, phlegmonous change or inflammatory mass on cross-sectional imaging with IV contrast (MR or CT) at two tertiary care centers were included between July 2006 and April 2023. Data collected included demographics, clinical characteristics, Montreal CD classification, treatments at the time of and after IAIM diagnosis, and size and location of the IAIM. Primary outcome was surgery defined as any CD-related resection or surgical drainage. Bivariate comparisons between patients who did or did not undergo surgery were performed. Multivariable logistic regression was performed with backward selection of variables to identify those associated with surgery. Results A total of 100 patients were included, and comparison between those who did or did not undergo surgery is given in Table 1. Most were white (80%), 44% were women, and 12% were current smokers. A majority had ileocolonic disease location (77%) and 50% were on a biologic at time of diagnosis. Mean size of IAIM was 3.4 cm and the majority (72%) were located adjacent to small bowel. Radiologic evidence of intra-abdominal fistula was seen in 40%, and 30% of patients had a stricture adjacent to the IAIM. A large proportion required hospitalization (75%) and received intravenous antibiotics (64%); 13% progressed to an abscess, and the mean (SD) time to abscess was 108 (119.4) days. The majority (65%) underwent surgery, with a mean (SD) time to surgery of 59 (97.8) days. Seven patients developed sepsis, all of whom subsequently required surgery. On multivariable analysis, patients were more likely to require surgery if there was a concomitant stricture (aOR = 3.12, 95% CI 1.01 – 11.9) and less likely to require surgery if treated with steroids (aOR = 0.15, 95% CI 0.03 – 0.61). Antibiotic use was not associated with surgery (aOR 1.22, 95% CI 0.53 – 2.81) nor was IAIM size. Conclusion In this large retrospective cohort, most intra-abdominal inflammatory masses required surgery, particularly if there was a concomitant stricture. Patients treated with steroids were less likely to require surgery though this may be confounded by severity of disease.