Nutritional–Inflammatory Recovery After Metal versus Plastic Biliary Stenting in Elderly Cholangiocarcinoma: A Prospective Observational Cohort Study

Background: Malignant biliary obstruction (MBO) in elderly cholangiocarcinoma is frequently accompanied by systemic inflammation and impaired immune-nutritional reserve. We compared stent durability and early nutrition-inflammation recovery after self-expandable metal stents (SEMS) versus plastic stents. Methods: We conducted a single‑center prospective observational cohort of consecutive patients aged ≥65 years undergoing first‑time biliary stenting (2019-2024; N=188; SEMS n=109; plastic stent n=79). The primary endpoint was time to recurrent biliary obstruction (TRBO; TOKYO criteria), with death treated as a competing event. Confounding was addressed using propensity score overlap weighting. Competing‑risk outcomes were analyzed with Fine-Gray regression overall survival (OS) with weighted Cox models, longitudinal GNRI, PNI, NLR, and log(SII) trajectories with mixed‑effects models. Prognostic associations were evaluated using a prespecified 30‑day landmark analysis. Results: At 6 months, the overlap‑weighted cumulative incidence of TRBO was 35.6% with SEMS versus 52.9% with plastic (sHR 0.64, 95% CI 0.44-0.93). SEMS was associated with fewer biliary reinterventions (any intervention 44.1% vs 68.2%; sHR 0.58, 95% CI 0.41-0.82). From baseline to day ~30, SEMS recipients had greater recovery in GNRI (mean difference +1.9; 95% CI 0.4-3.4) and PNI (+1.8; 95% CI 0.5-3.1) and a larger reduction in log(SII) (-0.10; 95% CI -0.19 to -0.01). In the landmark cohort (n=153), each 3‑point increase in ΔPNI was associated with lower mortality (HR 0.86, 95% CI 0.78-0.95), while higher day‑30 SII predicted higher mortality (per doubling HR 1.22, 95% CI 1.05-1.42). OS and 30‑day adverse events did not differ significantly. Conclusion: In elderly cholangiocarcinoma with MBO, SEMS was associated with lower TRBO and fewer reinterventions, and with more favorable early nutrition-inflammation recovery. Early PNI improvement and residual inflammatory burden at ~30 days provided prognostic information, supporting integrated post‑drainage nutrition-inflammation monitoring.