Blood Oxygen Levels Predict Stroke Risk in Children with Sickle Cell Anemia

People with sickle cell disease have a genetic error affecting their hemoglobin. The defect turns normally soft, round erythrocytes into inflexible, sickle-shaped cells. The altered shape causes blockages in blood vessels and prevents body tissues from receiving oxygen. Scientists have determined that the level, or saturation, of oxygen in blood could be used to identify children with sickle cell anemia who are at an increased risk of stroke.

Investigators reviewed the cases of 412 children with sickle cell disease who were initially diagnosed by newborn screening. All patients reviewed were born after January 1, 1990, a date chosen because patient data were available electronically. Oxygen saturation in the children's blood was tracked over time, and the records of those who suffered a stroke were compared to those who did not. The study found that children who had lower levels of oxygen in their blood were more likely to develop stroke.

The study was carried out by a team of investigators from the University of Texas (UT) Southwestern Medical Center (Dallas, TX, USA) and was reported the February 2008 edition of the British Journal of Haematology (BJH).
"A decline in oxygen saturation over time seems to further increase the risk of stroke,” said Dr. Quinn, assistant professor of pediatrics at UT Southwestern and lead author of the study. "Oxygen saturation is easily measured, potentially modifiable, and might be used to identify children with sickle cell disease who are at greater risk of having a stroke.”

Another study by Dr. Quinn and his colleagues appeared in the January 2008 issue of the journal Blood. That study examined how effectively a model developed by the Cooperative Study of Sickle Cell Disease (CSSCD) predicted severe disease in the newborn cohort. The CSSCD criteria, which evaluates patients based on factors such as occurrences of dactylitis--a type of painful swelling of the hands and feet--in the first year of life, steady-state hemoglobin concentration, and steady-state leukocyte count in the second year of life, was created in hopes that a predictive model would allow early, tailored therapy to prevent adverse outcomes.

Dr. Quinn reported that the findings suggest that the CSSCD model should not be used as the sole criterion to initiate early, high-risk intervention, and that a robust early prediction model is still needed.


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University of Texas Southwestern Medical Center