Adherence to and factors associated with hydroxyurea use in children ages 2 to 16 years old with sickle cell disease in North Carolina
Objectives Hydroxyurea (HU) is a disease modifying therapy approved for use in children 9 months and older with sickle cell anemia for stroke prevention; however, HU adherence continues to be low. We examined sociodemographic characteristics and HU adherence for 2 cohorts, 12-month Medicaid cohort versus 24-month Medicaid cohort. The study objective was to determine if longer continuous Medicaid enrollment was associated with better HU adherence. Methods Retrospective cohort study of HU adherence among children 2-16 years with SCD enrolled in NC Medicaid. Adherence assessed using HU Proportion of Days Covered (PDC), the sum of HU prescription fill days divided by the number of Medicaid days. Adherence was good if HU PDC was ≥80%, moderate 60%-79%, and poor <60%. Chi-square was used to determine differences in HU adherence between cohorts (12-month versus 24-month), and to identify any correlations of HU PDC with sociodemographic characteristics and predictor variables. Results The 12-month cohort, only 15% had Good/Moderate HU adherence while 85% had Poor HU adherence. The 24-month cohort had 25% of the participants with Good/Moderate HU adherence while 75% had Poor HU adherence. Overall, the 24-month cohort had higher HU adherence compared to the 12-month cohort (25% versus 15%, P =.0001). Of those children in the 24-month cohort with Good/Moderate HU adherence, 56% were school-aged and 26% were preschoolers as compared to those with Poor HU adherence as 41% were school-aged and 32% were adolescents (P =.0007). Conclusion HU adherence was low in children with SCD, though better for younger children with longer Medicaid enrollment.
