Comparative efficacy of subcutaneous infliximab switching in remission and non-remission patients with inflammatory bowel disease after intravenous maintenance: 1-year outcome from a multicentre cohort study

Background: Elective switching from intravenous (IV) to subcutaneous (SC) infliximab (IFX) has shown efficacy in patients with inflammatory bowel disease (IBD). However, long-term outcomes for patients not in remission remain unclear. Objectives: We evaluated the effectiveness of SC IFX switching in both remission and non-remission patients. Design: This study was a retrospective multicentre study conducted across five tertiary hospitals in Korea. Methods: Patients with IBD who switched to SC IFX between January 2021 and January 2023 were included. Clinical remission was defined as a Crohn’s Disease Activity Index of <150 or a partial Mayo score of <2. Biochemical remission was defined as faecal calprotectin of <250 µg/g and C-reactive protein of <0.5 mg/dL. We investigated the treatment persistence rate of SC IFX and trends in pharmacokinetics, clinical indices and biomarkers over 1 year of follow-up, analysing the data based on the baseline remission state. Results: Among 127 patients included, 90 (70.9%) were in clinical remission, and 37 (29.1%) were not at the time of switching. The one-year treatment persistence rate was 92.1%, with no significant difference between the clinical remission and non-remission groups (p = 0.139). Persistence was also unaffected by baseline biochemical remission status. IFX pharmacokinetics and biomarkers improved significantly in both clinical groups over 12 months (p < 0.005). Disease activity indices remained stable in the remission group and decreased in the non-remission group after switching. Previous biologics exposure was the only significant predictor of treatment persistence (hazard ratio, 5.634; 95% confidence interval, 1.357–23.384; p = 0.017). Adverse events related to SC IFX occurred in 15.7% of patients. The optimal SC IFX cutoff levels associated with clinical and biochemical remission were 11 and 17 μg/mL, respectively. Conclusion: Switching from IV to SC IFX during maintenance therapy demonstrated high treatment persistence and safety, irrespective of clinical and biochemical remission status.