1. Pediatric Rheumatology and Immunology Unit, Luis Calvo Mackenna Hospital, Santiago, Chile,
2. Pediatric Rheumatology and Immunology Unit, Luis Calvo Mackenna Hospital, Santiago, Chile
3. Pediatric Department, San Juan de Dios Hospital
4. Pediatric Service, Carabineros Hospital
5. Pediatric Service, Militar Hospital
6. Pediatric Service, Exequiel González Cortés Hospital
7. Pediatric Department, Pontificia Universidad Católica Hospital
8. Pediatric Service, Sótero del Río Hospital
9. Pediatric Department, Roberto del Río Hospital, Santiago, Chile