1. Division of Rheumatology, The Children's Hospital of Philadelphia, Philadelphia, PA
2. Department of Pediatrics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA
3. Division of Pediatric Pulmonology and Sleep Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA
4. College of Medicine, University of Illinois, Chicago, IL
5. Department of Anesthesia, Stanford University School of Medicine, Palo Alto, CA
6. Biostatistics Core of the Clinical and Translational Research Center (CTRC), The Children's Hospital of Philadelphia, Philadelphia, PA