Higher Prevalence of Hydroxyurea Use Is Associated with Lower Hospitalization Rate in a Population of Children with Sickle Cell Disease

Background: Individuals with sickle cell disease (SCD) treated with hydroxyurea (HU) in clinical trials have had fewer hospitalizations and vaso-occlusive pain episodes than those on placebo. Since 2014, HU has been recommended for all children with Hemoglobin SS/S-β0 thalassemia, and many SCD centers have increased HU utilization. The effect of expanded HU treatment on hospitalization rate has not been reported in a population of children clinically treated with HU. In a pediatric SCD center cohort, we tested the hypothesis that increasing prevalence of HU treatment was associated with reduced hospitalization rate per patient-year and in total hospitalizations. Methods: PedsNet, a PCORI-funded clinical research initiative, was queried for all patients with inpatient or outpatient encounters for SCD at St. Louis Children's Hospital (SLCH) from 2010 through 2015. Data from patients with ICD-9 codes indicating any genotype of SCD were included. Patients were considered to be receiving HU when it was prescribed on 2 or more outpatient encounters. Exclusion criteria were lack of SCD diagnosis confirmation, lack of outpatient visits at SLCH, and presence of a significant unrelated medical condition. Patients were censored at their 21st birthday or date of hematopoietic stem cell transplant. Data generated at the adult hospital were excluded. All hospitalizations in the final cohort were included for analysis, regardless of diagnosis code. For comparisons, patients were grouped as having a severe genotype (SS, S-β0 thalassemia, SD) or less-severe genotype (SC, S-β+ thalassemia). Statistical analysis was performed using SAS 9.4. Logistic and Poisson regression were used to compare proportions and rates between groups, respectively. Generalized Estimating Equations were used to account for within patient correlation. Abstract source