Parent education and biologic factors influence on cognition in sickle cell anemia

Abstract

Children with sickle cell anemia have a high prevalence of silent cerebral infarcts (SCIs) that are associated with decreased full-scale intelligence quotient (FSIQ). While the educational attainment of parents is a known strong predictor of the cognitive development of children in general, the role of parental education in sickle cell anemia along with other factors that adversely affect cognitive function (anemia, cerebral infarcts) is not known. We tested the hypothesis that both the presence of SCI and parental education would impact FSIQ in children with sickle cell anemia. A multicenter, cross-sectional study was conducted in 19 US sites of the Silent Infarct Transfusion Trial among children with sickle cell anemia, age 5-15 years. All were screened for SCIs. Participants with and without SCI were administered the Wechsler Abbreviated Scale of Intelligence. A total of 150 participants (107 with and 43 without SCIs) were included in the analysis. In a multivariable linear regression model for FSIQ, the absence of college education for the head of household was associated with a decrease of 6.2 points (P = 0.005); presence of SCI with a 5.2 point decrease (P = 0.017); each $1000 of family income per capita with a 0.33 point increase (P = 0.023); each increase of 1 year in age with a 0.96 point decrease (P = 0.023); and each 1% (absolute) decrease in hemoglobin oxygen saturation with 0.75 point decrease (P = 0.030). In conclusion, FSIQ in children with sickle cell anemia is best accounted for by a multivariate model that includes both biologic and socioenvironmental factors.

Figure 1

CONSORT diagram of children from the SIT Trial included in this study.

Figure 2

Effect of age, presence of SCI, and head of household education on predicted FSIQ. Model predictions with household per capita income and hemoglobin oxygen saturation fixed at mean value.

Figure 3

Meta-analyses for all studies in children with sickle cell anemia that included FSIQ for those with and without SCIs. The meta-analyses include a total of nine published studies and the current analysis that compares the mean difference in FSIQ between those children with sickle cell anemia with and without an SCI. The x-axis reflects the mean FSIQ difference between those with and without an SCI. The horizontal lines represent the upper and lower boundaries of the 95% confidence interval. If the 95% confidence interval overlaps zero or crosses the zero threshold then no statistical differences were observed in that study. The black and gray diamonds represent the results of the fixed and random effect models. The edges of the diamonds represent the 95% confidence interval of the meta-analyses for the fixed and random effect models.