Implementation quality as a modifiable determinant of filter lifespan in regional citrate anticoagulation: a real-world clustering-adjusted study.

Continuous renal replacement therapy (CRRT) is widely used in critically ill patients, but filter clotting remains a common complication. Regional citrate anticoagulation (RCA) is recommended; however, its real-world effectiveness may depend on implementation quality. This single-center retrospective cohort study analyzed 420 CRRT sessions from 1 September 2025 to 30 November 2025. Mixed-effects Cox models with patient-level random intercepts and competing-risk analysis were used. The primary outcome was filter clotting. In adjusted analyses, RCA was associated with a significantly reduced hazard of filter clotting compared with heparin (adjusted hazard ratio (aHR) for heparin vs. RCA: 1.78, 95% confidence interval (CI): 1.14-2.77, p = 0.011). Nafamostat showed no statistically significant difference from RCA (aHR: 1.31, 95% CI: 0.78-2.19, p = 0.31); however, the wide CI reflects limited sample size, and equivalence cannot be inferred. Within the RCA group, absence of timely post-filter ionized calcium (iCa2+) monitoring within 2 h was independently associated with increased clotting risk (adjusted odds ratio: 2.18, 95% CI: 1.24-3.84, p = 0.007), with a dose-response relationship (each one-hour delay increased clotting odds by 15%, p = 0.02). Major bleeding was infrequent (2.1% overall); metabolic complications (citrate accumulation) occurred in 2.9% of RCA sessions. In this cluster-adjusted real-world cohort, RCA was associated with improved filter survival compared with heparin. Implementation fidelity, particularly timely post-filter iCa2+ monitoring, appears to influence RCA effectiveness.