Socioeconomic status not linked to stroke risk in children with SCD
Study data also show that not using hydroxyurea greatly increases chances
Having a low household- or neighborhood-level socioeconomic status is not significantly associated with a higher risk of stroke in children with sickle cell disease (SCD).
These findings are based on a secondary analysis of data from the observational DISPLACE study (NCT03621826), which was originally designed to identify barriers to stroke screening and prevention in children ages 2 to 16 living in the U.S.
The data showed, however, that not using hydroxyurea, a standard medication for SCD, was significantly associated with an up to 19 times higher risk of stroke after adjusting for age, socioeconomic status, and certain blood test results. This confirms hydroxyurea’s previously reported protective effect against stroke in this patient population.
“This is a clear call to action for all providers to … ensure that individuals with SCD who are not currently prescribed [hydroxyurea] are offered appointments to discuss this medication,” researchers wrote.
The study, “Socioeconomic Status and Stroke Risk in Pediatric Sickle Cell Disease: A DISPLACE Study Secondary Analysis,” was published in Pediatric Blood Cancer.
People with SCD have higher risk of stroke
SCD occurs when red blood cells produce a faulty version of hemoglobin, the protein that carries oxygen throughout the body, making them acquire a sickle-like shape. These sickled red blood cells tend to stick together, which can block small blood vessels and trigger painful vaso-occlusive crises.
People with SCD are also at a higher risk of stroke, particularly children, as blood vessel blockage that occurs in the brain can prevent some regions from receiving enough oxygen and nutrients, causing damage.
Transcranial Doppler (TCD) ultrasound, which uses sound waves to measure how quickly blood flows through the brain, can help to identify children with SCD who have an increased risk for stroke. Blood flow speed is higher in areas of blood vessel blockages.
Chronic blood transfusions can decrease patients’ risk of stroke, but hydroxyurea, which is more accessible and affordable, is increasingly being used as an alternative strategy.
Social factors “at the household level (including lower parental education, higher number of adults and children in the home, food insecurity, etc.) are associated with increased risk of SCD-related acute care utilization,” the researchers wrote.
However, “whether socioeconomic status (SES) impacts the risk of having an abnormal transcranial doppler screening in SCD is unknown,” they added.
Household-level socioeconomic status measured by insurance type
To fill this knowledge gap, a team of researchers leveraged data from the DISPLACE study. The analysis included 3,124 children with SCD who had available TCD data and complete household or neighborhood socioeconomic status information.
The household-level SES was indirectly measured by the child’s insurance type, which was divided into public insurance — considered to be related to a low household socioeconomic status — and private or other insurance.
Neighborhood-level SES was estimated by the zip code-based Childhood Opportunity Index (COI), a score that measures the quality of neighborhood resources and conditions for children’s healthy development across three domains: education, health and environment, and social and economic. Children with very low COI were considered to be exposed to a low SES.
The included children had a median age of 5 years, and 50.6% were girls. More than half (64.6%) were exposed to low household SES, and 41.5% to low neighborhood SES.
While children’s age or sex did not differ significantly by household or neighborhood SES, those exposed to low household or neighborhood SES had significantly lower levels of hemoglobin and significantly more white blood cells, a marker of inflammation, than those not exposed to low SES.
Children exposed to low neighborhood-level SES were also significantly less likely to be treated with hydroxyurea, compared with those not exposed to low SES (54.9% vs. 56.2%).
Younger age significantly associated with higher stroke risk
Stroke risk was determined based on blood flow velocity measurements using TCD. Values below 170 cm/second represent a low risk for stroke. Values between 170 and 199 cm/second are classified as conditional TCD and identify children at a higher risk of an abnormal TCD. Finally, values of 200 cm/second or higher are classified as abnormal TCD and represent an elevated risk of stroke.
Initial statistical analyses showed that younger age was significantly associated with a higher stroke risk, as “median age of children with conditional and abnormal TCDs was 5 and 4 years, respectively, compared to 6 years for children with low-risk TCDs,” the team wrote.
Children in the conditional and abnormal TCD groups also had significantly lower hemoglobin levels and significantly higher white blood cell counts than those in the low-risk TCD group.
Rates of hydroxyurea prescription decreased from 92.9% in the low-risk TCD group to 81% in the conditional TCD group and 45.3% in the abnormal TCD group; these differences were statistically significant.
Children with abnormal TCDs were significantly more likely to live in proxied low household SES (77.8%) compared with those with conditional (56.8%) and low-risk (64.9%) TCDs. They were also more likely to live in proxied low-neighborhood SES (50% abnormal vs. 39.8% conditional vs. 41.4% low).
However, after adjusting for age and hemoglobin levels, only the lack of hydroxyurea prescription remained as an independent risk factor for a conditional TCD (increasing the risk by more than three times) or an abnormal TCD (increasing the risk by 20 times).
Analyses adjusted for proxied household and neighborhood SES, as well as white blood cell counts, resulted in similar results, with no hydroxyurea prescription being significantly linked to an about 3.5 times higher risk of conditional TCD and a 19 times increased risk of abnormal TCD.
“Our study reiterates the important relationship between [hydroxyurea] prescription and lower TCD velocities, and supports future investigation of the associations between family-reported SES and [hydroxyurea] prescription,” the researchers wrote.
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