Affiliation: | 1. Duke Pediatric Sickle Cell Program and Division of Pediatric Hematology/Oncology, Department of Pediatrics, Duke University Medical Center, Durham, North Carolina;2. Department of Hematology, St. Jude Children's Research Hospital, Memphis, Tennessee;3. Departments of Psychiatry, Surgery and Psychology and Neuroscience, Duke University Medical Center, Durham, North Carolina;4. Statistics, Rho, Inc., Chapel Hill, North Carolina |