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

Background Patients with moderate-to-severe inflammatory bowel disease (IBD) often require immunosuppressive therapy to achieve and maintain remission; however, the impact of these medications on influenza risk and the severity of influenza-related complications remains inadequately characterized. Methods Using the TriNetX U.S. Analytics Network, adults (≥ 18 years) with Crohn’s disease or ulcerative colitis during the 2022–2023 influenza season were identified. Patients were stratified by disease activity into two cohorts: (1) moderate-to-severe/active IBD, defined by elevated inflammatory markers, initiation of corticosteroids or a new biologic or small-molecule agent, or documented IBD-related symptoms or complications within the prior six months; and (2) mild/inactive IBD, defined by the absence of these features and no recent immunosuppressive therapy. Propensity score matching (1:1) was used to balance baseline characteristics, and Cox proportional hazards models were applied to estimate hazard ratios for influenza-related outcomes. Results After propensity score matching, each group had 22,784 patients. The incidence of influenza diagnosis was significantly higher in the moderate-to-severe/active IBD group (HR 1.41; 95% CI, 1.30–1.52). Hospitalization rates were also increased (HR 2.05; 95% CI, 1.89–2.23), as were influenza-related complications (HR 1.36; 95% CI, 1.23–1.51). ICU admissions (HR 1.51; 95% CI, 1.33–1.72) and mechanical ventilation (HR 1.68; 95% CI, 1.32–2.13) were both more frequent in the moderate-to-severe/active IBD group. Use of antiviral medications was higher among those in this cohort (HR 1.60; 95% CI, 1.22–2.10), and overall mortality was modestly increased (HR 1.17; 95% CI, 1.02–1.35). Subgroup analysis revealed the highest risk among patients on corticosteroids, followed by JAK inhibitors and anti–IL-23 agents. Conclusion Patients with moderate-to-severe/active IBD had more severe influenza-related outcomes compared with mild/inactive controls. Improving vaccine uptake and prompt evaluation of upper respiratory symptoms during influenza seasons are key to reducing influenza-related risks in immunosuppressed patients with IBD.