Vedolizumab in biologic-naïve ulcerative colitis: a multicenter real-world evaluation of clinical benefits and exploratory inflammatory indices.

Background and aims: Although vedolizumab (VDZ) serves as a primary biologic for ulcerative colitis (UC), long-term data in Chinese biologic-naïve cohorts and cost-effective prognostic biomarkers remain lacking. We evaluated the 54-week clinical benefits of VDZ as a first-line biologic in a Chinese cohort and investigated the clinical utility of systemic immune-inflammation indices (SII, NLR, PLR) in reflecting long-term outcomes and systemic inflammatory clearance during treatment de-escalation. Methods: This multicenter retrospective study enrolled biologic-naïve UC patients receiving VDZ. The primary endpoint was week-54 clinical remission, primarily evaluated using the full analysis set (FAS) with last observation carried forward (LOCF), accompanied by non-responder imputation (NRI) as a supplemental extreme-scenario analysis. Baseline indices were evaluated for predictive value, alongside an exploratory longitudinal analysis for patients undergoing early treatment de-escalation. Results: Among 41 patients in the FAS, the 54-week drug retention rate was 76.8%. Clinical remission was 73.2% (primary FAS-LOCF), with a conservative NRI estimate of 46.3%. In the paired endoscopy subgroup, 83.3% achieved endoscopic remission. While baseline SII and NLR correlated positively with C-reactive protein, they lacked robust predictive value for long-term remission. Instead, shorter disease duration was the sole independent predictor (OR = 0.84, Conclusions: Vedolizumab as a first-line biologic provides substantial clinical benefits and safety in bio-naive UC patients. While baseline inflammatory indices lack predictive power, their dynamic decline parallels clinical improvement. Due to the retrospective reliance on clinical symptoms and high rates of missing endoscopic data, these exploratory findings warrant cautious interpretation and prospective validation.