Efficacy of red blood cell transfusion in preventing a first stroke in children with sickle cell disease

Kaplan-Meier estimate of the probability of not having a stroke among 130 patients with sickle cell anemia at high risk of stroke as determined by transcranial Doppler; the patients were randomized to chronic long-term transfusion therapy or standard care. There was a significant benefit from transfusion therapy (p = 0.02). One patient in the standard-care group who had an intracerebral hematoma was excluded. The tick marks represent the lengths of observation in patients who did not have a stroke.