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Hydroxyurea is not as effective as transfusions in preventing recurrent strokes in children with sickle cell anemia

An article at Blood journal reports results from the Stroke With Transfusions Changing To Hydroxyurea (SWiTCH) study

May 13th 2012

Blood Comment

Among patients with sickle cell anemia, up to 11% will experience a clinical stroke by 20 years of age and 24% by 45 years of age. A previous study (STOP 1) demonstrated the efficacy of transfusion in preventing the occurrence of stroke in sickle cell anemia children with a high risk of experiencing a first stroke. Unfortunately, chronic transfusions do not abolish completely the risk of recurrent strokes and it induces iron overload along with the risk of red-cell alloimmunization. There is, therefore, an urgent need to find an equivalent or a better and more effective therapy to prevent recurrent strokes in sickle cell anemia patients. Hydroxyurea would not be the pursued alternative treatment, according to a recent study published in Blood, although it still may have some benefits in certain patients.

The article reports results from the Stroke With Transfusions Changing To Hydroxyurea (SWiTCH) study, designed to determine whether hydroxyurea is as effective as transfusions in preventing recurrent strokes in children with sickle cell anemia. The finding of strokes in 7 of 67children receiving hydroxyurea but none in 66 children who received transfusions led the authors to conclude that hydroxyurea is not effective in mitigating strokes. Dr. Mariane de Montalembert, ENERCA Partner from the Hopital Necker (Paris), comments the results of the study in an editorial published by the Blood journal.

Chronic transfusion is currently the standard of care for the prevention of recurrence of strokes in sickle cell anemia. There is a high risk of recurrence after discontinuation of transfusion therapy. On the other hand, hydroxyurea has been demonstrated to be effective in reducing pain in patients with severe sickle cell anemia. Its efficacy in preventing strokes was suggested by small studies where risk of stroke was reduced and where children with strokes on transfusion therapy had been successfully switched to hydroxyurea treatment. The present randomized study comparing the effectiveness of hydroxyurea and of transfusion in 134 children suggests it is not a safe alternative to transfusion in sickle cell anemia patients having had a stroke.

The SWiTCH study was terminated before its completion because the reduction in liver iron content was not superior in the hydroxyurea arm, and 7 strokes had been observed in the 67 subjects enrolled in this arm compared with 0 in the 66 subjects on transfusion. The conclusion of this paper is that transfusion and chelation remain a better way to manage children with sickle cell anemia, stroke, and iron overload. However, Dr. Mariane de Montalembert notes the initial neurologic abnormalities of the children in the present study were rather severe. New studies are necessary to determine if hydroxyurea may be useful in patients with less severe damage. She underlines too that very early screening of cerebrovascular lesions is extremely important to prevent progressive accumulation of vascular damage.

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