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 STOP Study
In 1997, the Stroke Prevention Trial in Sickle Cell Anemia
(STOP) proved that transcranial Doppler (TCD) ultrasound screening and
chronic transfusion could reduce the annual incidence of first clinical
stroke in high-risk children from about 10% per year to about 1% per year.
This led to recommendations for TCD screening of all children with sickle
cell disease (SCD) and transfusions for those with abnormal TCD velocities.
In this study led by the Medical College of Georgia and
New England Research Institutes, 130
children ages 2-16 were randomly assigned to receive either transfusions or
standard care. The National Heart, Lung, and Blood Institute funded the
study
Children with time-averaged maximum mean (TAMM) velocities of 200 cm/sec or
higher in the middle cerebral artery (MCA) or distal internal carotid artery
(dICA) were eligible for the study. These blood vessels were chosen because
blockage of the MCA and dICA is the most frequent cause of brain infarction
in these patients.
If a clinic were following 200 children with SCD without stroke, about one
child would have a stroke each year. This is a 0.5% incidence rate.
Transfusing all 200 patients could prevent the first stroke, but this would
not be an optimal use of resources. With the STOP strategy, about 10
patients are treated each year to prevent one stroke. Better prediction
methods could further reduce the number of patients needing to be treated to
prevent the first stroke. |
