1. Pediatric Physician’s Organization at Children’s, Brookline, Massachusetts;
2. Division of General Pediatrics, and
3. Department of Pediatrics, Harvard Medical School, Boston, Massachusetts;
4. Slone Epidemiology Center, and
5. Schools of Medicine and Public Health, Boston University, Boston, Massachusetts; and
6. Clinical Research Center, Boston Children’s Hospital, Boston, Massachusetts;
7. Division of General Pediatrics and Adolescent Medicine, University of North Carolina, Chapel Hill, North Carolina