ANCA-associated vasculitis (AAV), a rare disease that causes inflammation in blood vessels, is understudied in children and often presents with life-threatening disease. This project focuses on improving how researchers measure health-related quality of life and long-term consequences in children with AAV to support more advance research studies in the future. To do this, the study uses two major data sources: the largest group of children with AAV identified through PEDSnet, a U.S. network that includes electronic health record data from more than 13 million children, and the pediatric Vasculitis Patient Powered Research Network (pedsVPPRN), an international registry where patients and caregivers share health information and quality-of-life data over time. Using these resources, the study will first improve and test a tool to measure long-term damage from vasculitis, including a new portion specifically designed for children. Researchers will work with providers, other CARRA investigators, patients, and caregivers to ensure the measures reflect what matters most for children with vasculitis. The study also aims to understand which life circumstances and health complications are linked to worse quality of life for children living with this condition. Examples include age at diagnosis, missed school, and serious health issues like dialysis. The long-term goal is to identify ways to better measure and address the challenges children with vasculitis face, while engaging both families and providers throughout CARRA to guide future research and improve care.