Risk-based Therapy for Sickle Cell Anemia: A Feasibility Study

Sickle cell anemia (SCA) patients experience organ damage that begins at an early age and
results in significant morbidity and early mortality. Although all SCA patients share the
same genetic mutation, the clinical complications are highly variable with some patients
experiencing frequent and severe complications, while others have few serious complications.
If SCA severity could be predicted early in life, those patients at greatest risk for
complications could receive treatment prior to the onset of organ damage. No general SCA
severity predictor or one that can be informative early in life exists. The investigators
preliminary research has identified the absolute reticulocyte count (ARC) as a potential
early predictive risk marker for SCA complications in pediatric patients. A higher ARC
between ages 2 and 6 months of age is associated with an increased risk of hospitalization in
the first 3 years of life; the mean ARC for the 36 patients who were hospitalized for SCA
complications was significantly higher than that of the remaining 23 in those who were not
hospitalized. Moreover, total hospitalizations were nearly three times higher by age 2 years
in those infants who had an ARC of > 200 than for those infants whose ARC was <200. The
proposed study will determine if ARC can be used as a risk-stratifier in asymptomatic infants
with SCA and ascertain its value in targeting hydroxyurea therapy to those infants at highest
risk of SCA sequelae.