Patterns and Predictors of Hydroxyurea Use Among Californians Living With Sickle Cell Disease.

Hydroxyurea is the primary disease-modifying therapy for sickle cell disease (SCD), yet adherence is low. Our objective was to identify patterns and predictors of hydroxyurea adherence among Medicaid enrollees with SCD. Children and adults with SCD who received Medicaid benefits between 2009 and 2018 in California were included. Monthly hydroxyurea possession ratios were calculated using filled hydroxyurea prescriptions. Group-based trajectory modeling was applied to identify hydroxyurea possession trajectories and multinomial logistic regression modeling to evaluate predictors of hydroxyurea possession group membership: prior acute care visits due to VOCs, prescriber specialty, and participant sex and age. 713 participants (48% in the 0 to 17 age group, 50% male) had 3 distinct hydroxyurea possession groups: persistently high (n=263, 37%), moderate to low (n=253, 35%), and low to no possession (n=197, 28%). The 18 to 24 and 25+ age groups had greater odds of being in the moderate to low (OR: 2.62, 1.70) and low to no (OR: 3.60, 2.45) than the persistently high possession group compared with the 0 to 17 age group when adjusted for prior VOCs. Children had greater odds of being in the persistently high hydroxyurea possession group compared with young adults and adults, suggesting there are protective factors at this age that promotes better hydroxyurea adherence.