Response:

We thank the authors for summarizing the Belgian experience with transcranial doppler (TCD) for children with sickle cell disease (SCD). Although their data are retrospective, they describe significant differences in the TCD velocities of children treated with hydroxyurea compared with those who were not. Similar to our findings,1  children with highest baseline TCD velocities had the greatest treatment-related decreases. Their data also provide additional support for the use of hydroxyurea for primary and even secondary stroke prevention in children with SCD. We are encouraged that these pilot data further document the benefits of hydroxyurea for children with SCD, yet we maintain that treatment at the maximum tolerated dose is preferred.2  As we concluded in our paper, controlled multicenter prospective trials are needed to determine the efficacy of hydroxyurea therapy in these clinical settings.

Conflict-of-interest disclosure: The author declares no competing financial interests.

Correspondence: Russell E. Ware, Department of Hematology, St Jude Children's Research Hospital, MS 355, 332 N Lauderdale Street, Memphis, TN 38105-2974; e-mail: russell.ware@stjude.org.

1
Zimmerman
 
SA
Schultz
 
WH
Burgett
 
B
Mortier
 
NA
Ware
 
RE
Hydroxyurea therapy lowers transcranial Doppler flow velocities in children with sickle cell anemia.
Blood
2007
110
1043
1047
2
Zimmerman
 
SA
Schultz
 
WH
Davis
 
DS
et al
Sustained long-term hematologic efficacy of hydroxyurea at maximum tolerated dose in children with sickle cell disease.
Blood
2004
103
2039
2045
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