The Chronic Kidney Disease in Children (CKiD) Study is a multi-center cohort study of children aged 6 months to 16 years with mild to moderate impaired kidney function. Two clinical coordinating centers (CCCs; Children's Hospital of Philadelphia and Children's Mercy Kansas City) and a data coordinating center (Johns Hopkins Bloomberg School of Public Health) have formed a cooperative agreement to conduct a prospective study of chronic kidney disease in children. During the 2018 to 2023 funding cycle, we established links with the University of Minnesota for measurement of iohexol GFR which will be maintained and expanded to all centralized measurements were they to be selected as the Central Biochemistry Laboratory for the 2023-2028 cycle, but infrastructure is in place to work with whichever institution is selected. Since its inception in 2003, CKiD aims are to determine the risk factors for decline in kidney function and define how progressive decline in kidney function is associated with cardiovascular health; neurocognitive function and behavior; and growth. The purpose of this application is to propose new initiatives to continue the cohort study from August 2023 to July 2028. The substantive scientific aims are described in the application from the collaborating CCCs. This application describes the role that the KIdney Disease in children data Management and Analysis Center (KIDMAC) will perform as the data coordinating center. We will continue to provide leadership in study design, coordination and conduct, data management and analytical methodology and thereby enhance the scientific scope of CKiD. The specific aims of KIDMAC are: 1) to provide biostatistical and epidemiological study design expertise including the recruitment of 14-17 year olds with pediatric chronic kidney disease (CKD) to follow through the transition to adult care, remote data collection from a variety of sources to complement in-person study visits, and a targeted design for iohexol GFR measurement among those with higher kidney function to validate and refine the newly proposed Under 25 (U25) eGFR equations; 2) to provide the Steering Committee, the two CCCs, the CBL and the scientific subcommittees with an infrastructure to coordinate and conduct CKiD research activities; 3) to transition to web-based Research Electronic Data Capture (REDCap) to capture and manage CKiD data; 4) to provide biostatistical and epidemiological leadership in the analysis, interpretation and presentation of study- wide initiatives including the development of methods for the appropriate analyses of the CKiD data (e.g., mixture models to identify distinct clinical subgroups, machine learning methodology for prediction) to understand the impact of childhood CKD on kidney function decline in children and young adulthood and incidence of cardiovascular outcomes in young adulthood; and 5) to implement a quality assurance program that integrates expertise in data management, study coordination,...