Neurocognitive Impairment Predicts Poor Transition Outcomes Among Patients with Sickle Cell Disease

Introduction: In the United States, most children with sickle cell disease (SCD) survive into adulthood and transfer from pediatric to adult-centered care. Cognitive deficits begin during childhood and are highly prevalent among individuals with SCD, potentially affecting their functional ability to establish adult care and navigate the new adult care environment. Lack of engagement in adult care can place youth with SCD at higher risk for care discontinuity and higher disease morbidity and mortality. The relationship between cognition and transition to adult care has not been examined. We hypothesized that better performance on measures of neurocognition were associated with decreased latency in initiating adult care, greater retention in adult care, and increased utilization of adult ambulatory services. As a secondary objective, we examined the relationship of environmental outcomes to transition outcomes.

Methods: We included participants enrolled in the Sickle Cell Research and Intervention Program (SCCRIP; Hankins J. et al, Pediatric Blood and Cancer 2018), a longitudinal lifetime cohort study of individuals with SCD that monitors neurocognition. Participants were included if they underwent neurocognitive screening assessment in adolescence, prior to their transfer to adult care and if they satisfied their first appointment in adult care. The neurocognitive screening battery included measures of estimated global intelligence (Wechsler Abbreviated Scales of Intelligence, 2^nd Ed; WASI-2) and sustained attention (Continuous Performance Test, 2^nd Ed; CPT-2). Environmental factors included the Economic Hardship Index (EHI), guardian employment status while in pediatric care, and the number of persons living in the household. Use of adult ambulatory services was measured by the number of outpatient visits per patient-year. The association between cognitive performance and the latency from pediatric to adult care, adult care retention and environmental variables was examined using the 2-sample t test if the data were normally distributed or the Wilcoxon rank-sum test otherwise. Categorical variables were analyzed with the Chi-square test or Fisher's exact test. Transition outcomes were also analyzed as continuous variables using univariate linear regression. All reported p-values are two-sided.

Results: Eighty adolescents with SCD ages 15-18 years at the time of their cognitive assessment (58% male, 63% HbSS/HbSβ⁰-thalassemia) were included; most transferred <6 months from the last pediatric visit Table 1). Of these 80 patients, 61 and 43 had sufficient follow-up time to examine their retention in adult care 12 and 24 months after transfer, respectively. Fifty out of the 61 patients (82%) remained in adult care > 12 months, and 31 of the 43 (72%) remained in adult care >24 months after their first adult visit. Higher Full-Scale IQ was associated with establishing adult care ≤2 months from last pediatric visit (Table 1; Figure 1A, 1B). Belonging to families with fewer children, smaller households and a higher WASI-2 Verbal Comprehension Index were associated with establishing adult care ≤6 months from last pediatric visit. Better CPT-2 Commissions performance (less attention deficit) was associated with increased adult care retention at 12 and 24 months (Table 2; Figure 1C,1D). Having a working guardian was associated with less retention at 12 months (p=0.01), whereas having an unemployed primary guardian was associated with greater retention at 24 months (p=0.02). Further, an employed guardian was associated with greater utilization of adult ambulatory services (p=0.01). EHI was not significantly related to transition outcomes. No relationship was found between adult ambulatory services and neurocognitive assessment.

Conclusion: Neurocognitive deficit (lower IQ and attention deficits) may decrease short and long-term engagement in adult care among youth with SCD as demonstrated by longer latency periods between pediatric and adult care and shorter adult care retention. Socio-economic factors may also play a role in transition outcomes but require further investigation. Investigation of disease modifying therapies that preserve cognitive function should be prioritized. Interventions that account for patients' cognitive level and their environment should be considered in the individualization of transition plans.

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