Systemic Inflammation Response Index (SIRI) and Aggregate Index of Systemic Inflammation (AISI) as Predictors of Mortality in Patients with Upper Gastrointestinal Bleeding

<b>Background/Objectives</b>: Systemic inflammatory markers have recently gained attention as prognostic indicators in various acute conditions. However, their predictive value in non-variceal upper gastrointestinal bleeding (UGIB) remains uncertain. This study aimed to evaluate the prognostic performance of the Systemic Inflammation Response Index (SIRI) and the Aggregate Index of Systemic Inflammation (AISI) for in-hospital mortality among patients with non-variceal UGIB and to compare them with established clinical scoring systems. <b>Methods</b>: This retrospective cohort study included 531 adult patients admitted with non-variceal UGIB between April 2023 and February 2025. Demographic, clinical, and laboratory data were collected at presentation. Inflammatory indices (SIRI, AISI, AISI/Hb) and established risk scores (Glasgow-Blatchford, Rockall, AIMS-65, and ABC) were calculated. The primary outcome was all-cause in-hospital mortality. Discriminatory ability was assessed using receiver operating characteristic (ROC) curve analysis, and independent predictors were identified by multivariable logistic regression. <b>Results</b>: The overall in-hospital mortality rate was 4.7% (25/531). Non-survivors were older and had lower systolic blood pressure, higher serum urea, and elevated inflammatory indices. Among biomarkers, SIRI (AUC = 0.773, 95% CI: 0.737-0.809) and AISI (AUC = 0.709, 95% CI: 0.670-0.747) showed good discriminatory ability, comparable to AIMS-65 (AUC = 0.765) and ABC (AUC = 0.786). In multivariable models, SIRI (OR = 1.10, <i>p</i> = 0.011) and AISI (OR = 1.04 per 100 units, <i>p</i> = 0.003) remained independent predictors of mortality after adjustment for age, systolic blood pressure, hemoglobin, serum urea, and albumin. <b>Conclusions</b>: SIRI and AISI are independent predictors of in-hospital mortality in patients with non-variceal UGIB, demonstrating comparable prognostic performance to conventional risk scores. These readily available inflammatory indices may serve as simple and cost-effective adjuncts for early risk stratification in clinical practice.