clinics of the University Teaching Hospital, Ado-Ekiti, Ekiti state, in southwestern Nigeria; and Aminu Kano University Teaching Hospital, Kano, in northwestern Nigeria. All consecutive children with SCA in stable state who were attending the hematology clinic of the hospitals for routine follow-up care were recruited. Informed consent was taken from the caregiver and/or the child when able to do so after thorough explanation of the reason(s) for the study. Also, ethical clearance was obtained from the Ethics and Research Committee of the two hospitals independently