Impact of Gaps in Care during Adult Care Transfer in Sickle Cell Disease
Authors: Howell Kristen E , Kayle Mariam , Smeltzer Matthew P , Nolan Vikki , Gurney James G , Mathias Joacy , Porter Jerlym S. , Nelson Marquita , Anderson Sheila , Shah Nirmish , Hankins Jane S 
Published: November 2021

Abstract
The transition from pediatric to adult health care is critical to the care of young adults with sickle cell disease (SCD). Young adults with SCD, compared with children with SCD, are at risk for a marked increase in disease severity, frequency of acute complications, healthcare utilization, and mortality. 1-4 Professional societies and healthcare experts recommend that young adults with chronic health conditions should transfer to adult-centered healthcare within 6 months of their last pediatric visit. 5-8 However, the effect of a 6-month transfer interval on healthcare utilization in SCD has not been studied. Given the complex health care needs of young adults with SCD, 9-15 it remains unclear whether the recommended 6-month transfer interval 5 is optimal. We hypothesized that longer gaps between pediatric and adult care would be associated with greater healthcare utilization in the first 2 to 6 years of adult care.
This study included patients with SCD who were followed by a pediatric sickle cell program in the mid-southern US, participated in a transition to adult care program, 16 and fulfilled an initial adult visit to a partner adult SCD facility during the years 2011-2017. Participants were retrospectively followed from their first adult visit through December 31, 2017. Transfer gap was defined as the time (in months) between the last pediatric and the first adult sickle cell clinic visit. We estimated the association between varying transfer gaps from pediatric to adult care and the rate of healthcare utilization (inpatient, emergency department, and outpatient visits) in the first 2 to 6 years of adult care using negative binomial regression. Transfer gaps were evaluated at &lt;2, ≥2 to &lt;6, ≥6 to &lt;9, and ≥9 months to evaluate whether adult health care utilization increased as the gap in SCD-specific care increased. Transfer gaps were also dichotomized at 6 months (&gt;6 vs ≤6) to evaluate the current recommendation to complete transfer of patients to adult care within 6 months. 6,7 Healthcare resource utilization was analyzed for the complete follow-up (up to 6 years) and for the first 2 years of adult care to assess the immediate effects of delayed transfer.
In total, 172 young adults with SCD (52% male, 63% HbSS/HbSβ 0-thalassemia) transferred to adult care at a median age of 18 years during the years 2011-2017 (Table 1). Approximately 83% of the included participants transferred to adult care within the recommended 6 months. young adults with transfer gaps ≥9 months had 2.86 (95%CI: 1.32, 6.20) times the rate of acute healthcare visits (inpatient and emergency department combined) compared to those with &lt;2 months transfer gap (Table 2). The incidence rate ratio increased (IRR: 4.06; 95%CI: 1.65, 9.94) when evaluating the first 2 years of adult care. When evaluating the recommended transfer gap (6 months) as a dichotomous variable, those with gaps &gt;6 months had 2.27 (95%CI: 1.18, 4.40) times the rate of acute care visits compared to those with ≤6 months transfer gap (Table 3). The incidence rate ratio increased slightly (IRR: 2.37; 95%CI: 1.29, 4.37) when evaluating the first 2 years of adult care only. There were no apparent associations between transfer gap duration and outpatient visits during the first 6 years in adult care; however, when restricted to the first 2 years of adult care, those with gaps &gt;6 months had 1.32 (95%CI: 1.01, 1.72) times the rate of outpatient visits compared to those with gaps ≤6 months.
Consistent with current guidelines, transfer gaps between pediatric and adult-centered care of greater than 6 months were found to be associated with increased acute healthcare resource utilization. Therefore, SCD transition programs would be well-served to consider policies for young adults that initiate adult care within 6 months of leaving pediatric care. Future studies should continue to investigate duration of transfer gaps from pediatric to adult care for their long-term clinical effects and explore interventions to reduce the transfer gap in the SCD population.
Figure 1 Figure 1.

Disclosures
Shah: Novartis: Consultancy, Research Funding, Speakers Bureau; GBT: Research Funding, Speakers Bureau; Alexion: Speakers Bureau; Guidepoint Global: Consultancy; GLG: Consultancy; Emmaus: Consultancy. Hankins: Bluebird Bio: Consultancy; UpToDate: Consultancy; Vindico Medical Education: Consultancy; Global Blood Therapeutics: Consultancy.