1. Divisions of Rheumatology and
2. Center for Pediatric Clinical Effectiveness, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania;
3. Departments of Pediatrics and
4. Center for Clinical Epidemiology and Biostatistics,
5. Biostatistics,
6. Child Health Corporation of America, Shawnee Mission, Kansas
7. General Pediatrics and
8. Leonard Davis Institute of Health Economics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania; and