(P086) THE IMPACT OF OBESITY ON RESPONSE TO INFLIXIMAB SALVAGE THERAPY IN PATIENTS WITH ACUTE SEVERE ULCERATIVE COLITIS 

Background: Infliximab, an anti-tumor necrosis factor-alpha (TNF-α) agent, is well-established as salvage therapy in hospitalized patients with acute severe ulcerative colitis (ASUC) who do not respond to intravenous (IV) corticosteroids. Furthermore, obesity rates among patients with inflammatory bowel disease (IBD) are increasing, and it is unknown how obesity impacts treatment response in this setting. It has been postulated that obese individuals (Body Mass Index ≥30.0 kg/m²) may have decreased response to infliximab. While the exact mechanism remains unclear, it is hypothesized that excess adipose tissue increases baseline inflammatory cytokines and alters the pharmacokinetics of anti-TNF-α agents through changes in absorption and clearance. This study aimed to evaluate the impact of obesity on clinical outcomes in patients receiving infliximab for ASUC. 

Methods: We conducted a single-center, retrospective analysis of adult patients ( >18 years old) admitted to our institution for ASUC who received inpatient infliximab salvage therapy between January 1, 2010 and October 31, 2023. Patients were categorized into two comparison groups: non-obese (BMI 18.5-29.9) and obese (BMI ≥ 30.0). Treatment response was measured by the rates of readmission (within 90-days and 1-year) and surgical intervention (during hospitalization, within 30-days, and within 1-year). Fisher exact test with alpha of 0.05 was used to compare proportions between groups.  

Results: A total of 84 patients met the inclusion criteria: 64 non-obese and 20 obese. There were 4 patients (3 non-obese, 1 obese) who were lost to follow-up after 30 days and excluded from data analyses beyond that point. The 90-day readmission rate was 24.2% (15/62) for the non-obese and 32.6% (6/19) for the obese (p = 0.5567). The 1-year readmission rates were 38.7% (24/62) for non-obese and 42.1% (8/19) for obese (p = 0.7949). Surgical intervention rates during hospitalization were 3.13% (2/64) for non-obese and 10% (2/20) for obese (p = 0.2388). Within 30 days, surgical intervention rates were 4.69% (3/64) for non-obese and 5% (1/20) for obese (p = 1.0). The 1-year intervention rates were 14.6% (9/61) for non-obese and 21.1% (4/19) for obese (p = 0.4959).  

Conclusion: There was no statistically significant difference between the rates of readmissions and surgical interventions in non-obese and obese patients receiving infliximab salvage therapy for ASUC. However, it is noteworthy that obese patients exhibited higher rates of surgical intervention. Nonetheless, the impact of obesity on infliximab response in ASUC remains unknown. Further data and larger studies are needed to determine whether obesity negatively affects infliximab response in ASUC and namely to determine the optimal dosing strategy in this setting.