S1515 Severe Influenza-Related Outcomes in Patients With Inflammatory Bowel Disease on Immunosuppressive Therapy: A Propensity-Matched Cohort Analysis

Introduction: Patients with inflammatory bowel disease (IBD) often require immunosuppressive therapy to induce and maintain remission. However, the impact of recent immunosuppression on the severity of influenza-related complications needs to be quantitated. We aimed to evaluate whether recent immunosuppressive therapy increases the risk of these complications. Methods: We used the TriNetX Analytics Network, to examine adults (≥18 years) with a diagnosis of Crohn’s disease (K50.x) or ulcerative colitis (K51.x) during the 2022–2023 influenza season. Patients with recent immunosuppressive therapy (within 6 months) were compared to those without, using 1:1 propensity score matching (PSM) to balance baseline characteristics. Outcomes assessed included influenza infection and related complications during the influenza season. Results: A total of 93,793 patients were identified, including 39,741 in the immunosuppressive group and 44,795 in the non-immunosuppressive IBD group. After PSM, each group had 39,741 patients (mean [SD] age, 50 [18] years; 54% women). The incidence of influenza diagnosis was significantly higher in the immunosuppressive group (7.1% vs 4.5%; HR, 1.51; 95% CI, 1.43–1.60; P < 0.001). Hospitalization rates were also increased (6.8% vs 4.5%; HR, 1.48; 95% CI, 1.38–1.58; P < 0.001), as were influenza-related complications (4.0% vs 2.5%; HR, 1.51; 95% CI, 1.39–1.63; P < 0.001). ICU admissions (2.4% vs 1.6%; HR, 1.38; 95% CI, 1.25–1.52; P < 0.001) and mechanical ventilation (0.7% vs 0.5%; HR, 1.32; 95% CI, 1.10–1.59; P = 0.003) were both more frequent in the immunosuppressive group. Use of antiviral medications was higher among those in the immunosuppressive cohort (0.8% vs 0.3%; HR, 2.24; 95% CI, 1.82–2.76; P < 0.001), and overall mortality was modestly increased (1.1% vs 0.9%; HR, 1.17; 95% CI, 1.02–1.35; P = 0.001). Subgroup analysis revealed the highest risks among patients on corticosteroids (HR 1.62, 95% CI 1.53–1.72), followed by JAK inhibitors (HR 1.53, 95% CI 1.43–1.63), and anti-IL-23 agents (HR 1.53, 95% CI 1.43–1.63). Anti-IL-12/23 and anti-TNF agents were also associated with elevated risks. Conclusion: Patients with IBD requiring immunosuppressive therapy had a significantly higher risk of influenza infection and severe complications compared to non-immunosuppressed counterparts. These findings highlight the importance of annual influenza vaccination and timely antiviral treatment in patients with IBD, particularly those on immunosuppressive therapy.