Histologic Activity Modifies the Predictive Value of Systemic Inflammatory Markers in Ulcerative Colitis

Background/Objectives: Systemic inflammatory markers may predict relapse in ulcerative colitis (UC), but whether histologic activity modifies their prognostic value remains unclear. We evaluated whether baseline neutrophil-to-lymphocyte ratio (NLR), lymphocyte-to-monocyte ratio (LMR), and neutrophil-to-platelet ratio (NPR) predict clinical relapse in UC patients with endoscopic improvement and whether these associations differ by histologic status. Methods: This retrospective cohort study included UC patients with Mayo Endoscopic Subscore 0 or 1. Histologic status was assessed using the Geboes score and classified as histologic improvement (<3.1) or histologic activity (≥3.1). Baseline NLR, LMR, and NPR were calculated. Clinical relapse was the primary outcome. Cox proportional hazards models and Kaplan–Meier analyses were performed. Results: Histologic activity was present in 132 patients (30.3%). Baseline inflammatory indices did not differ between groups. Higher baseline NLR was associated with relapse in the histologic activity subgroup (hazard ratio [HR], 1.72; 95% confidence interval [CI], 1.06–2.92; p = 0.028), but not in the histologic improvement subgroup (HR, 0.98; 95% CI, 0.70–1.38; p = 0.901). After adjustment for endoscopic activity, high NLR remained independently associated with relapse in patients with histologic activity (HR, 1.83; 95% CI, 1.10–2.05; p = 0.021), with significant interaction by histologic status (p = 0.019). LMR and NPR were not associated with relapse. Conclusions: Histologic activity modifies the prognostic value of baseline NLR in UC patients with endoscopic improvement. Combining NLR with histologic assessment may improve relapse risk stratification.