OBJECTIVES: Although not approved for use in pediatrics, hydroxyurea has been shown to decrease painful vaso-occlusive events and hospitalizations (HU) in children with sickle cell disease (SCD), a genetic hematologic disorder primarily affecting people of African descent. However, few data exist on the use of HU, and adherence to treatment, in real-world settings. This study assessed the extent to which children with SCD are adherent with prescribed HU therapy and the association between HU adherence and economic outcomes in this population in a real-world setting.
METHODS: Insurance claims of North Carolina Medicaid program enrollees (June 1999-August 2008) were analyzed. Inclusion criteria were ≥1 claims with a diagnosis for SCD (i.e., ICD-9-CM 282.6, 282.6x), ≥2 HU prescriptions in the year following HU initiation, ≤18 years old at the time of HU initiation, and continuous Medicaid enrollment for ≥12 months prior to and following HU initiation. Adherence was measured using the medication possession ratio (MPR), with MPR > 0.8 considered adherent. Multivariable models were estimated to assess the association between HU adherence and economic outcomes (e.g., inpatient costs) in the first year of HU therapy.
RESULTS: A total of 159 subjects (55% female, mean age [SD] 11.3 [4.4] years) met all inclusion criteria. The mean MPR was 0.63, with 41% of subjects adherent. Multivariable models revealed that in the year following HU initiation, adherence was associated with a reduction in all-cause (-$3.695, p = 0.0003) and SCD-related (-$3.002, P < 0.0001) total, inpatient (-$2172, p = 0.001; -$1815, P < 0.0001, respectively), ER (-$314, P < 0.0001; -$202, p = 0.002, respectively), outpatient (-$951, P < 0.0001; -$541, p = 0.005, respectively), and vaso-occlusive event-related (-$3639, P < 0.0001) costs, and an increase in all-cause (+$239, p = 0.014) and SCD-related pharmacy (+$198, P < 0.0001) costs.
CONCLUSIONS: Adherence to HU among pediatric SCD patients may be suboptimal and improving adherence to HU therapy among these patients may reduce the economic burden of the illness.
