Component-Level Prognostic Evaluation of Clinical, Inflammatory, and Renal-Protein Markers for 30-Day Mortality in Older Patients with Perforated Peptic Ulcer.

Objective: To compare clinical and laboratory markers for 30-day mortality in older patients with perforated peptic ulcer and assess biochemical markers beyond age and American Society of Anesthesiologists (ASA) class. Methods: Patients aged ≥65 years undergoing emergency surgery for perforated peptic ulcer from January 2015 to February 2026 were retrospectively analyzed. Discrimination was assessed by the area under the receiver operating characteristic curve (AUC), and incremental value by likelihood-ratio tests and Brier scores. Six marker-specific incremental tests underwent Benjamini-Hochberg false discovery rate (FDR) adjustment. Models incorporating blood urea nitrogen-to-albumin ratio (BAR) or log2-transformed creatinine underwent bootstrap internal validation. Results: Thirty-day mortality was 37.7% (26/69). Age and ASA class yielded AUCs of 0.785 and 0.755. BAR had the highest univariable biochemical discrimination (AUC, 0.777). Inflammation-based indices showed limited discrimination (AUC, 0.424-0.492); Prognostic Nutritional Index (PNI) had the highest discrimination among immune-nutritional/composite markers (AUC, 0.636; p = 0.061). BAR improved the age- and ASA-based model nominally (p = 0.023), but not after FDR adjustment (adjusted p = 0.068). Creatinine provided the strongest incremental information (AUC, 0.905; Brier score, 0.123; adjusted p = 0.008). In the joint model, creatinine improved fit beyond BAR (p = 0.024), whereas BAR did not improve fit beyond creatinine (p = 0.773). Conclusions: Prognostic information was concentrated in age, ASA class, and renal-protein markers. Creatinine provided the most consistent incremental information; BAR showed high univariable discrimination but did not retain significant incremental value after FDR adjustment. Inflammation-based indices remained limited. Independent validation is required.