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Hydroxyurea was approved in 1967 for treating certain types of cancer. In 1998, the drug was approved to reduce the frequency of painful crises and to reduce the need for blood transfusions in adult patients with sickle cell disease (SCD) with recurrent moderate to severe painful crises. Hydroxyurea was approved for pediatric use by FDA in 2017 to reduce the frequency of painful crises and to reduce the need for blood transfusions in pediatric patients, two years of age and older, with sickle cell anemia with recurrent moderate to severe painful crises. Since the pediatric approval, little has been published about hydroxyurea utilization patterns in pediatric populations. FDA conducted three analyses in the Sentinel Distributed Database, an analysis using data from 2000 to 2015 and two analyses using data from 2000 to 2020. In these analyses, FDA assessed the utilization of hydroxyurea by age group and indication and evaluated the number of hospitalizations/emergency department (ED) visits in patients with SCD for two time frames: (1) any observed time up until a patient’s first hydroxyurea dispensing, and (2) among patients with hydroxyurea use, observed time following their first hydroxyurea dispensing.
The two analyses which used data from 2000 to 2020 entailed slightly different cohort entry requirements. In the first analysis, Sentinel results identified 113,036 patients of any age with SCD who were active in the data source sometime between January 2000 and September 2020. Of these patients, 16,483 patients (15%) were ever dispensed hydroxyurea. Among the 45,472 African American patients with SCD, 10,339 patients (23%) had hydroxyurea use, compared to 13% of patients with an unspecified race and 2% of Caucasian patients. A total of 96,297 adult patients 18 years old or older with SCD were identified, 13,740 (14%) of whom were dispensed hydroxyurea. Over three-quarters of adult patients had at least one hospitalization or ED visit (for any medical condition). The analysis showed 29.4 hospitalizations or ED visits per 10 person-years among adult patients with SCD while not dispensed hydroxyurea, and 79.4 hospitalizations or ED visits per 10 person-years among adult patients with SCD after being dispensed hydroxyurea. Of note, disease severity was not accounted for in this analysis.
This analysis also identified 16,739 pediatric patients aged 17 years old and younger with SCD, of whom 2,743 patients (16%) were ever dispensed hydroxyurea. Among all pediatric patients with SCD, 11,457 patients (68%) had at least one hospitalization or ED visit (for any medical condition, 15.8 events per 10 person-years). While not dispensed hydroxyurea, pediatric patients with SCD had 12.9 hospitalizations or ED visits per 10 person-years, compared to 30.5 hospitalizations or ED visits per 10 person-years after being dispensed hydroxyurea (not accounting for disease severity).
The second analysis identified 14,294 patients of all ages with SCD who had health plan enrollment during the 183 days prior to their first observed hydroxyurea dispensing, of whom 5,872 patients (41%) received at least one year of therapy, cumulatively. Approximately half of the pediatric patients 17 years old or younger who received hydroxyurea received at least one year of therapy, cumulatively, compared to 39% of adult patients 18 years old or older having received at least one year of therapy.
These analyses informed FDA about real-world utilization patterns for hydroxyurea among pediatric and adult patients with SCD from 2000 to 2020.