S433 Impact of Radiation Proctocolitis on Outcomes in Patients Hospitalized With Clostridioides difficile Infection: A Population-Based Study

Introduction: Radiation proctocolitis (RP) is a complication of pelvic radiotherapy, characterized by mucosal inflammation and friability that may alter intestinal homeostasis. While RP has been associated with bleeding and chronic diarrhea, its effect on outcomes in patients with Clostridioides difficile infection (CDI) remains poorly understood. This study assesses the clinical impact of RP in CDI hospitalizations using a nationally representative database. Methods: We conducted a retrospective cohort study using the National Inpatient Sample (NIS) from 2020 to 2022. Adult hospitalizations with a principal diagnosis of CDI were identified using International Classification of Diseases, Tenth Revision codes, and RP was identified as a secondary diagnosis. Baseline characteristics were compared using survey-weighted descriptive statistics. Multivariable regression models assessed the association between RP and inpatient outcomes. The primary outcome was inpatient mortality. Secondary outcomes included length of stay (LOS), total hospitalization charges, acute kidney injury (AKI), and septic shock. Models were adjusted for age, sex, race, Charlson comorbidity index, insurance type, income quartile, and hospital-level factors. Results: Among an estimated 162,404 adult CDI hospitalizations, 0.19% (n ≈ 309) had a co-diagnosis of RP. Compared to those without RP, these patients were older (mean age 67.9 vs 67.1 years, P < 0.001), less likely to be women (47.6% vs 63.5%, P = 0.0084), and less likely to be White (65.7% vs 77.8%, P = 0.0006). They also had a significantly higher comorbidity burden, with a Charlson index ≥3 in 72.1% compared to 41.9% in the non-RP group (P < 0.001). In multivariable analysis, RP was not independently associated with increased inpatient mortality (adjusted odds ratio [aOR] 0.82, 95% confidence interval [CI]: 0.11–6.09, P = 0.827). There was no statistically significant difference in LOS (added 0.57 days; 95% CI −0.78 to 1.91; P = 0.409) or total hospital charges (added $7,153; 95% CI −$4,146 to $18,561; P = 0.215). Additionally, there were no significant associations between RP and AKI (aOR 0.95; P = 0.851) or septic shock (aOR 1.15; P = 0.885). Conclusion: Although patients with RP hospitalized for CDI were older and had a greater comorbidity burden, the presence of RP was not independently associated with increased mortality, resource utilization, or complications. These findings suggest that RP does not worsen the clinical course of CDI and that standard inpatient management strategies remain appropriate for this population.