Long-Term Effects of Hydroxyurea in Children With Sickle Cell Anemia (The BABY HUG Follow-up Study)

SCA is an inherited blood disorder in which the body makes sickle-shaped red blood cells that contain abnormal hemoglobin. The sickled cells block blood flow in the vessels that lead to limbs and organs. This can cause pain, serious infections, and organ damage. The BABY HUG study (NCT00006400) is examining whether the medication hydroxyurea can prevent organ damage, especially in the spleen and kidneys, in children with SCA. This study is a follow-up study to the BABY HUG study and will enroll children who have participated in the BABY HUG study. The purpose of this study is to examine the long-term effects of using hydroxyurea as a treatment for SCA, including both the risks and benefits. Study researchers will also investigate the optimal age to begin treatment with hydroxyurea in children with SCA.

This study will enroll children between 2 and 7 years old who participated in the BABY HUG study. Hydroxyurea will not be provided to participants as part of this study, but participants may receive the medication from their own doctors. Parents of participants can choose for their child to participate in this study in one of two ways-by enrolling in either a passive follow-up group or an active follow-up group. For participants in the passive follow-up group, study researchers will review participants' medical records every 6 months, in addition to reviewing brain ultrasound tests and computed tomography (CT) or magnetic resonance imaging (MRI) scans, if completed. Participants will have a blood and urine collection at baseline and Year 4 (or at the end of the study, whichever comes first). Participants in the active follow-up group will take part in the same study procedures as participants in the passive follow-up group. In addition, at Year 2, participants in this group will undergo an additional blood and urine collection, a scanning procedure to obtain images of the liver and spleen, a kidney test, neuropsychological testing, and an ultrasound imaging test to evaluate liver and spleen size.