Long-term effect of AST-120 on delaying renal replacement therapy initiation in CKD: A propensity score overlap-weighted retrospective cohort study.

BACKGROUND: AST-120, an oral adsorbent targeting uremic toxins, has shown inconsistent renoprotective effects in randomized trials. Whether AST-120 is associated with delayed renal replacement therapy (RRT) initiation in real-world chronic kidney disease (CKD) populations remains uncertain. METHODS: We conducted a retrospective cohort study of adults with CKD stages 3-5. AST-120 exposure was defined as at least 30 days of prescription during the first year after cohort entry, and treatment status was fixed at the start of follow-up. The primary outcome was RRT initiation, assessed over up to 8 years. Propensity score overlap weighting was used to balance baseline demographic, clinical, medication, and laboratory covariates. Sequential Cox proportional hazards models, weighted Kaplan-Meier analyses, and exploratory subgroup analyses were performed. RESULTS: Among 426 eligible patients, 199 were AST-120 users, and 227 were non-users. Before weighting, AST-120 users had more advanced CKD and higher serum creatinine levels. After overlap weighting, baseline covariates were well balanced, with absolute standardized differences below 0.1. AST-120 use was not associated with RRT risk in the crude model (HR, 1.20; 95% CI, 0.71-2.03; P = 0.502), but was significantly associated with lower RRT risk after overlap weighting and full adjustment, including CKD stage (HR, 0.41; 95% CI, 0.22-0.78; P = 0.007). Weighted Kaplan-Meier analyses showed higher 8-year RRT-free survival overall (P = 0.015) and in CKD stage 3 (P = 0.035). No subgroup showed a significant interaction. CONCLUSION: AST-120 use was associated with lower long-term RRT risk, even after correcting for confounding by indication.