Sociodemographic and Biomedical Correlates of Developmental Delay in 2- and 4-Year-Olds with Sickle Cell Disease

Mind the gap: trajectory of cognitive development in young individuals with sickle cell disease: a cross-sectional study

STUDY OBJECTIVES

Compared to typically developing children and young adults (CYA-TD), those living with Sickle Cell Disease (CYA-SCD) experience more cognitive difficulties, particularly with executive function. Few studies have examined the relative importance of silent cerebral infarction (SCI), haemoglobin and arterial oxygen content on age-related cognitive changes using cross-sectional or longitudinal (developmental trajectory) data. This study presents cohort data from a single timepoint to inform studies with multiple timepoints.

METHODS

We compared cross-sectional raw and scaled scores as age-related changes in cognition (trajectories) in CYA-SCD and age-and ethnicity-matched CYA-TD. We also compared cross-sectional age-related changes in cognition (trajectories) in CYA-SCD with and without SCI to CYA-TD. General cognitive abilities were assessed using Wechsler Intelligence Scales, including the Verbal Comprehension Index (VCI) and Perceptual Reasoning Index (PRI) underpinning IQ. Executive function was evaluated using the Delis-Kaplan Executive Function System (D-KEFS) Tower subtest and the Behaviour Rating Inventory of Executive Function (BRIEF) questionnaire. SCI were identified from contemporaneous 3 T MRI; participants with overt stroke were excluded. Recent haemoglobin was available and oxygen saturation (SpO2) was measured on the day of the MRI.

RESULTS

Data were available for 120 CYA-SCD [62 male; age = 16.78 ± 4.79 years; 42 (35%) with SCI] and 53 CYA-TD (23 male; age = 17.36 ± 5.16). Compared with CYA-TD, CYA-SCD experienced a delayed onset in VCI and slower rate of development for BRIEF Global Executive Composite, Metacognition Index (MI), and Behaviour Regulation Index. The rate of executive function development for the BRIEF MI differed significantly between CYA-TD and CYA-SCD, with those with SCI showing a 26% delay compared with CYA-TD. For CYA-SCD with SCI, arterial oxygen content explained 22% of the variance in VCI and 37% in PRI, while haemoglobin explained 29% of the variance in PRI.

CONCLUSION

Age-related cognitive trajectories of CYA-SCD may not be impaired but may progress more slowly. Longitudinal studies are required, using tests unaffected by practice. In addition to initiation of medical treatment, including measures to improve arterial oxygen content, early cognitive intervention, educational support, and delivery of extracurricular activities could support cognitive development for CYA-SCD.Graphical Abstract.

Implementation of Two Developmental Screening Programs in Sickle Cell Disease Specialty Care

Objective

Developmental screening is a critical component of care for children with sickle cell disease (SCD), who are at elevated risk for neurodevelopmental disorders. This report describes the implementation of two related developmental screening programs implemented in different SCD specialty care settings with the purpose of describing screening protocols, outcomes, and lessons learned.

Methods

Program One reviewed medical records for 201 children with SCD screened at ages 2 and 4 years. Program Two reviewed program tracking and visit notes for 155 screenings across 67 children screened between 9 and 66 months of age. Key outcomes included characteristics of children screened, screening results, concordance between parent concerns and screening outcomes, and access to evaluation and intervention services.

Results

Each program identified a substantial number of children with developmental concerns, including 42% of screenings in Program One and 36% of unique children screened in Program Two. Program One resulted in 56% of identified children receiving follow-up developmental services and 62% receiving developmental monitoring. Program Two resulted in 58% of identified children receiving further evaluation following developmental screening, with 67-75% of children with neurodevelopmental diagnoses receiving intervention services following evaluation. While parent concerns were related to screening outcomes, screening instruments detected many children whose parents did not express developmental concerns.

Conclusions

Routine developmental screening is a feasible, acceptable, and effective method for identifying concerns in children with SCD in specialty care. Flexible and collaborative care and sustainability are key considerations for effective programming, with pediatric psychologists uniquely positioned to provide optimal integrated care.

Current developmental screening practices in young children with sickle cell disease

Despite recent developmental screening guidelines, rates of neurodevelopmental disorders (NDDs) remain lower than expected in children with sickle cell disease (SCD). A retrospective chart review identified 276 eligible patients; 214 charts were available for developmental screening and 207 charts for autism-specific screening. Developmental surveillance/screening was conducted in 70% of charts and autism-specific screening in 19% of charts. Validated tools were used in 32% of developmental screenings and 92% of autism-specific screenings. Many children (57%) were screened outside recommended ages. In conclusion, children with SCD are not regularly receiving appropriate developmental screening and surveillance by their healthcare providers.

Neurocognitive functioning in preschool children with sickle cell disease

BACKGROUND

Children with sickle cell disease (SCD) experience neurodevelopmental delays; however, there is limited research with preschool-age children. This study examined neurocognitive risk and protective factors in preschoolers with SCD.

PROCEDURE

Sixty-two patients with SCD (60% HbSS/HbSβ⁰ -thalassemia; 40% HbSC/HbSβ⁺ -thalassemia) between the ages of 3 and 6 years (mean = 4.77 years) received a neuropsychological evaluation as routine systematic surveillance. Patients were not selected for disease severity, prior central nervous system findings, or existing cognitive concerns. Thirty-four patients (82% HbSS/HbSβ⁰ -thalassemia) were prescribed hydroxyurea (HU) at the time of their neuropsychological evaluation. On average, these patients had been prescribed HU at 2.15 (standard deviation = 1.45) years of age. The average dose was 28.8 mg/kg/day. Besides genotype, there were no group differences in medical or demographic factors based on HU treatment status.

RESULTS

Patients with HbSS/HbSβ⁰ -thalassemia scored below normative expectations on measures of intelligence, verbal comprehension, and school readiness (false discovery rate-adjusted p-value [p_FDR ] < .05). Age, sickle genotype, and HU treatment exposure were not associated with measured neurocognitive outcomes (p_FDR  > .05). Greater social vulnerability at the community level was associated with poorer performance on measures of intellectual functioning, verbal comprehension, visuomotor control, and school readiness, as well as parent report of executive dysfunction (p_FDR  < .05). Greater household socioeconomic status was positively associated with academic readiness.

CONCLUSIONS

Preschoolers with severe SCD (HbSS/HbSβ⁰ -thalassemia) perform below age expectations on measures of intelligence and academic readiness. Sociodemographic factors were stronger drivers of neurocognitive performance than disease severity or disease-modifying treatment. Neurodevelopmental interventions targeting the home and broader community environment are needed.