Annual stroke incidence in Nigerian children with sickle cell disease and elevated TCD velocities treated with hydroxyurea

Background Elevated transcranial Doppler (TCD) velocities accurately predict stroke risk in children with sickle cell disease (SCD). Chronic blood transfusion, the gold standard for primary stroke prevention, is faced with numerous challenges in Africa. Hydroxyurea (HU) has been shown to reduce elevated TCD velocities in children with SCD. Aim To determine the effectiveness of HU in reducing the risk of primary stroke in a cohort of Nigerian children with SCD and elevated velocities treated with HU. Methods Children with SCD and TCD velocities >= 170 cm/sec treated with HU were prospectively followed with 3-monthly TCD and neurological evaluations for >= 12 months to determine the incidence of primary stroke. Results One hundred and four children, 53 males, and 51 females were enrolled into the study. Their ages ranged from 2 to 16 years with a mean of 6 years. At first TCD examination, velocities ranged from 173 to 260 cm/sec with conditional and abnormal risk velocities in 60 (57.7%) and 44 (42.3%) children, respectively. Follow up ranged from 1 to 8 years with a mean of 3.6 years. Mean TCD velocities showed a significant decline from 198.2 (standard deviation [SD] = 15.6) cm/sec to 169.3 (SD = 21.4) cm/sec (P < 0.001). One stroke event occurred in the cohort, giving a stroke incidence of 0.27/100 person years. Conclusion HU significantly reduces TCD velocities in Nigerian children with SCD and elevated TCD velocities, with a corresponding reduction in the incidence of primary stroke. HU may represent a potential alternative for primary stroke prevention in low and middle income countries where the burden of SCD resides.