Trends in Hospital Utilization for Acute Illness in a Large Population-Based Cohort of Children and Adolescents with Sickle Cell Disease (SCD): 2010–2017
Authors: Lai Kristina , Anand Sonia , Quarmyne Maa-Ohui , Dampier Carlton , Lane Peter A. , Ibrahim Amenah 
Published: October 2019

Abstract
Disease severity and healthcare utilization varies widely among persons with sickle cell disease (SCD). Hydroxyurea (HU) has been demonstrated to reduce rates of pain and acute chest syndrome, the leading causes of inpatient utilization in patients with Hb SS and S β°-thalassemia in clinical trials. We recently reported that HU was clinically effective in reducing rates of pain and acute chest syndrome in patients who initiate treatment. Use of hydroxyurea in SS/S β°-thalassemia has increased markedly since 2010. Thus we sought to detemine trends of hospital utilization for acute illness during an 8 yr in which HU utilization increased markedly (2010-2017). Data from years 2010-201 were obtained from the SCD database and patient records at Children's Healthcare of Atlanta (CHOA). Utilization data were restricted to acute care admissions. Admissions for elective procedures, non-SCD related discharge diagnoses, rare SCD genotypes, and patients who had undergone bone marrow transplant were excluded. Patients were compared based on number of hospitalizations, age, sex, SCD genotype (SS/S β°-thalassemia vs Hb SC/S β+thalassemia), and discharge diagnosis. A total of 3,116 patients had at least one encounter between 2010 and 2017; 2,947 patients met inclusion criteria. From 2010-2017 the total number of active patients per year increased from 1,546 patients to 1,789 patients (+16%), while the total number acute care admissions increased from 1,295 admissions to 1,609 admissions (+24%). There were no significant differences in the proportion of patients with genotypes SS/S β° thalassemia genotypes (67.0% vs 63.9%, p=0.06). Overall patients with SS/S β° thalassemia had higher admission rates compared to SC/S β+ thalassemia patients (0.94 vs 0.57 admissions per patient per year). During the study period. overall admission rates in SCD (acute illness hospitalizations/patient/yr) increased from a low of 0.74 in 2011 to a high of 0.90 in 2017. The proportion of admissions attributed to SS/S β°-thalassemia patients decreased (79.2% in 2010 vs 72.3% in 2017, p<0.0001). However, admission rate in SC/S β+ thalassemia increased (0.53 to 0.69 admissions per patient per year). Overall, over 60% of patients were not admitted in any given year, and the proportion of patients with 0-1 admissions in a given year remained unchanged. However, the proportion of super high hospital utilizers (SHHU), patients with 8 or more admissions in a given year, increased by 185%. In 2001 this group made up 0.6% of all patients and accounted for 7.3% of admissions; in 2017 SHHU had increased 1.8% of patients and 24.3% of admissions. There was no difference in genotype or sex between SHHU and non-SHHU patients. SHHU were older (>90% of patients over age 8 years), and had greater percentages of admissions for pain and acute chest syndrome then non-SHHU. In conclusion, during a period in which HU utilization in SS/S β°-thalassemia increased significantly, hospital utilization for acute illness in SS/S β° thalassemia decreased as expected. However, during the same period there was an unexpected increase in overall hospital utilization for acute illness in SCD. This increase in hospital utilization was the result of 1) a marked increase in SHHU and 2) an overall increased utilization in SC/S β+ thalassemia.

Disclosures
Dampier: Pfizer: Research Funding.