Supplementary Material for: Hypertonic Citrate Solution Protocol Associated with Longer Filter Lifetime in Critically Ill Patients Requiring Continuous Kidney Replacement Therapy

Background: Regional citrate anticoagulation (RCA) serves as the first line of anticoagulants in continuous kidney replacement therapy (CKRT). Premature circuit clotting is associated with increased workload, costs, and adverse patient outcomes. Current evidence shows limited studies on the relationship between RCA protocols and circuit clotting in RCA CKRT. The study aims to investigate the factors influencing filter lifetime that lead to premature circuit clotting, including citrate formulas employed during RCA in CKRT. Methods: This retrospective cohort study was conducted at a single center and included patients receiving CKRT from February 2023 to September 2023. The primary outcome was the identification of factors associated premature circuit clotting. Secondary outcomes included circuit ionized calcium levels, citrate doses, blood transfusions, citrate formulations, and other variables that may impact filter clotting. Results: A total of 199 filters from 97 patients were analyzed in this study. After exclusion of circuit termination due to non-clotting event, 38 filters experienced premature circuit clotting (lifetime ≤ 72 hours), while 70 filters clotted after 72 hours. The baseline characteristics and clinical outcomes were well balanced between the groups. In the multivariable analysis, only isotonic citrate formulations (RR 2.45, 95% CI 1.17-5.14, p = 0.018) and corrected citrate doses (RR 0.48, 95% CI 0.27-0.87, p = 0.016) exhibited statistically significant associations with filter premature clotting. Conclusions: Different RCA prescriptions may affect filter lifetime and circuit integrity. Notably, the hypertonic RCA protocol was associated with a significantly longer filter lifetime compared to the isotonic RCA protocol. However, additional data from rigorously constructed randomized controlled trials are needed.