Gout Epidemiology in Chronic Kidney Disease: Transition to End-stage Kidney Disease and Impact of Renal Transplant - PROJECT SUMMARY Gout coexisting with advanced chronic kidney disease (CKD) poses a complex and under-researched medical challenge. There is scant evidence and an important knowledge gap to guide gout management in patients transitioning from advanced CKD to end-stage kidney disease (ESKD), where dialysis or kidney transplantation (KT) becomes necessary. Understanding the burden of gout during the transition from non- dialysis CKD to ESKD and subsequently to KT is essential for optimizing treatment strategies and improving patient outcomes. This research, utilizing data from the United States Renal Data System (USRDS), aims to explore the evolution of gout burden (including flares and healthcare utilization) from advanced CKD to ESKD, and for those undergoing KT. Our overarching goal is to test the central hypothesis that individuals with concomitant gout and CKD progressing to dialysis (ESKD) will have an increased burden of gout (flares, emergency room visits, hospitalization, and cardiovascular disease) during the period of transition into dialysis. In addition, gout burden after kidney transplantation has decreased after the transition of anti-rejection regiments to those not using cyclosporine (primarily) and calcineurin inhibitors in general. We will test this hypothesis using data from the United States Renal Data System (USRDS) and the United Network for Organ Sharing (UNOS). For this, we will apply a self-controlled case series (SCCS) method, where individuals act as their own controls, reducing the influence of between-person confounding variables. We will also conduct a retrospective cohort study examining the change in the incidence of gout, immunosuppressive regimes, and related patient outcomes in Kidney Transplantation. The two aims will rigorously evaluate the natural history of the gout burden in critical phases of CKD and ESKD . The goal of Aim 1 (CKD to ESKD aim) examine the trajectory of gout burden and treatment patterns as patients transition from advanced CKD to ESKD. The goal of Aim 2 (Kidney transplantation aim) is to assess changes in gout incidence, gout flares, and outcomes including cardiovascular hospitalizations and mortality among KT recipients.