Transcranial Doppler (TCD) velocities in the TWiTCH trial

The TWiTCH trial randomly assigned children with sickle cell disease at high risk of stroke who had already received chronic transfusions for one or more years to receive continued transfusions (standard group) or to transition to hydroxyurea according to the trial protocol (alternative group). The primary endpoint was TCD velocity. Data in each group are shown as the mean plus or minus one standard deviation. Refer to UpToDate topic on stroke prevention in sickle cell disease for further interpretation, context, and approach.