Association of IV vs. Oral Iron Therapy With Clinical Outcomes in Patients With Advanced CKD

Rationale & Objective: The long-term outcomes associated with IV vs. oral iron replacement therapy in patients with chronic kidney disease (CKD) are unclear.We investigated the association of IV vs oral iron replacement therapy with incident end-stage kidney disease (ESKD) and with all-cause mortality in a national cohort of US Veterans with eGFR <60ml/min/1.73m 2 .Study Design: National VA historical cohort study.Setting & Participants: 17,428 incident new users of oral iron replacement therapy and a comparable group of 879 incident new users of IV iron replacement therapy during October 1, 2004, through September 30, 2006, with longitudinal follow-up until September 30, 2019.Predictor: Incident new use of oral vs. IV IRT. Outcomes: ESKD and mortality.Analytical Approach: We examined the association of oral vs IV IRT with outcomes using competing risk regression and Cox models.We used propensity score matching to account for differences in baseline characteristics.Results: Event rates were overall higher in patients receiving IV iron replacement, but the risk was mitigated after PS matching, with no significant association observed between the type of iron therapy and ESKD (subhazard ratio: 1.07, 95%CI: 0.82-1.39,p=0.6), or all-cause mortality (hazard ratio: 1.07, 95%CI: 0.96-1.20,p=0.2).Limitations: Potential selection bias and residual confounding. Conclusions:In this large national cohort of patients with chronic kidney disease, IV iron was not significantly associated with higher risk of incident ESKD and all-cause mortality when J o u r n a l P r e -p r o o f compared to oral iron therapy.The comparative effectiveness of the different iron replacement modalities will need to be studied further in clinical trials.