ASH: Stroke in Sickle Cell Children Reduced by Screening
SAN FRANCISCO, Dec. 8 -- Screening by transcranial Doppler ultrasound, followed by transfusion therapy, almost eliminated the risk of a stroke among children with sickle cell disease, a researcher said here.
In a retrospective cohort analysis, the screening cut the rate of overt stroke by a factor of 10, "a remarkable reduction," Janet Kwiatkowski, M.D., of the Children's Hospital of Philadelphia said at the American Society of Hematology meeting.
Transcranial Doppler ultrasound measures the speed of blood flow in the internal carotid and the middle cerebral arteries. Narrowing of the vessels leads to faster blood flow.
Stroke is rare in children, she said, but those with sickle cell disease have roughly 300 times the risk that's seen in the general pediatric population. Dr. Kwiatkowski said the procedure became standard practice at her institution for children two through 18 years after studies showed it could help predict children at risk and that regular transfusions could lower the risk. Following those studies, she said, the hospital instituted screening for all children with sickle cell disease in September 1998, followed by transfusions for children at risk. To evaluate the procedure, she and colleagues analyzed medical records of all children treated at the hospital for the eight years before the screening program started and the eight years afterward. The analysis found that the incidence of overt stroke before the screening was started was 0.67 per 100 patient-years, while afterward it was reduced to 0.06 per 100 patient-years.
"It really does work," Dr. Kwiatkowski said.
For the study, a neurologist reviewed all clinical data and radiological studies for each event and classified them into overt stroke (ischemic or hemorrhagic), other neurological event, or indeterminate, she said.
The analysis found:
The procedure "has almost eliminated symptomatic stroke in our patients," she said. The picture is actually even better, she said, because one of the post-screening strokes occurred in an infant who was too young for the screening program. Dr. Kwiatkowski said the value of the procedure could be enhanced by expanding the age groups recommended for screening and also by expanding access to screening. Currently, she said, many centers are using the procedure "but some are slow to come on board."
She added that the procedure is technically difficult to perform, which makes it difficult for centers with a low patient load to develop the needed expertise. In a study that may make it easier, Texas researchers found that daytime hemoglobin saturation is associated with higher blood flow to the brain as measured by transcranial Doppler ultrasound. With colleagues, Charles Quinn, M.D., of the University of Texas Southwestern Medical Center in Dallas retrospectively analyzed measurements in 169 children with sickle cell disease.
They found that lower hemoglobin saturations (measured at the same time) were significantly correlated (P0.001) with faster blood flow in the right and left middle cerebral arteries. Dr. Quinn said the analysis showed that every 1% decrease in oxygen saturation was associated with about a 1.5% increase in the odds of having an abnormal transcranial Doppler velocity.
Dr. Kwiatkowski's study is important because it emphasizes "the importance of regionalization of healthcare for children with sickle cell," said Michael DeBaun, M.D., of Saint Louis Children's Hospital, who was not part of the studies. He co-moderated the press conference at which the research was presented.
The children in Dr. Kwiatkowski's analysis received "expert care at a tertiary medical center," he said, but not all children have access to such a high level of care. But when they do, Dr. DeBaun said, "we can anticipate that the rate of stroke will drop."
Primary source: Blood
Enninful-Eghan H, et al "Transcranial Doppler screening program Is effective in preventing stroke in children with sickle cell disease" Blood 2008; 112(11): Abstract 714.
Additional source: Blood
Variste J, et al. "Daytime steady-state hemoglobin saturation Is a determinant of cerebral artery blood flow velocity in children with sickle cell anemia" Blood 2008; 112(11): Abstract 1424.
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