LEARNING HEALTH SYSTEM CORE SUMMARY The Pediatric Center of Excellence in Nephrology (PCEN) at the Children's Hospital of Philadelphia (CHOP) is designed to accelerate evidence generation in childhood kidney diseases through infrastructure that helps overcome the many challenges to conducting rapid and efficient clinical research studies. PEDSnet, a growing multi-specialty network of nine of the nation's largest pediatric academic health systems, has harmonized their diverse electronic health record (EHR) systems to develop a national architecture to rapidly implement learning health systems (LHS) across all pediatric health conditions. The LHS Core of the PCEN has partnered with PEDSnet to establish a national interconnected, multi-institutional infrastructure able to reach large numbers of children with kidney disease and to provide the depth of information necessary to comprehensively characterize their clinical course and outcomes and to evaluate therapies. The LHS Core takes advantage of the expertise and infrastructure developed during the construction of PEDSnet to provide methodologic, informatics, and study development support to Center investigators and to expand the broad PEDSnet database to meet the needs of PCEN-sponsored studies. The embedded Pediatric Nephrology Data Resource achieves both scale and efficiency for EHR data currently being collected on over 8 million children with an emphasis on data elements and data quality optimization central to studies of pediatric kidney disease. In order to accelerate evidence generation and advance evaluations of interventions in pediatric nephrology, the LHS Core will: expand and facilitate access to pediatric- and kidney-specific structured data in the Pediatric Nephrology Data Resource and produce annual clinical insight reports for childhood kidney disorders; stimulate and support high quality observational studies using the Pediatric Nephrology Data Resource by providing technical and methodological resources to investigators; and expand Core services to enhance infrastructure for comparative effectiveness research and pragmatic clinical trials in pediatric nephrology and leverage this infrastructure to decrease time to trial implementation. In addition to providing access to this unique data resource, LHS Core services will include computable phenotyping, augmented structured data and variable definitions relevant to pediatric kidney disease, an active chart review program, patient-reported outcomes and survey administration, data science and methodological consultation, self-service query tools, privacy preserving linkage to other data resources, connection to pediatric nephrology and urology LHS initiatives, rapid administrative start-up, prep-to-trial services, a multi-institutional kidney biopsy registry, real-world data for external control matching, and EHR-facilitated recruitment. The Core team comprises expertise in data science, epidemiology, health services research, and pati...