Despite the well-documented benefits of hydroxyurea (HU) therapy in decreasing morbidity and mortality in youth with Sickle cell disease (SCD), pediatric HU adherence rates range as low as 49% and lead to discontinuation of HU regimens in 8-20%. In addition, treatment non-adherence may lead to unnecessary increases in medication dosage resulting from erroneous assumption that a patient is non-responsive to treatment (versus non-adherent to the regimen as prescribed). Given the detrimental effects of non-adherence, assessment of and intervention for HU non-adherence is essential to improving health outcomes in the pediatric SCD population.

Electronic adherence monitoring is widely considered the "gold standard" in objective adherence measurement. These monitors provide continuous, real- time records of medication adherence and reveal problematic behavior patterns, including underdosing, overdosing, delayed dosing, "drug holidays," and "white coat" adherence. Overall, electronic adherence measures are considered valid, reliable, and accurate, with clear advantages over pharmacy refill records, physician estimates and self-report measures.

The primary purpose of this pilot study is to determine the use of the AdhereTech as a feasible and valid measure of HU adherence in pediatric SCD.

Primary Objective Estimate the association between HU adherence as measured by the AdhereTech device to a) caregiver-report, b) youth-report, c) lab values, d) pill- count, and e) Medication Possession Ratio (MPR) adherence measures Secondary Objectives Estimate the rate of consent to the study, the rate of AdhereTech device use, the rate of AdhereTech device failure, and the perceived acceptability of using the AdhereTech device, as reported by caregivers and youth

The AdhereTech smart bottle is an electronic medicine dispenser with a tracking and reminder system connected wirelessly. The device provides real time adherence aids to the patient and this information is relayed to the provider. The device can sense the amount of pills remaining inside the bottle. This information is measured periodically and concurrently sent to a secure database using cellular data technology. Thus, AdhereTech bottles can be used to determine whether medication was removed from the bottle, the amount of medication removed, and the timing of removal.

Participants ages 12.0-17.99 who are receiving HU prescribed in pill form will use the AdhereTech smart bottle for a two-month period. Participants and their caregivers will complete self-report measures of adherence at the baseline, 1 month and 2 month clinic visits, a Demographic questionnaire at the baseline clinic visit and an Acceptability questionnaire at the 1 month and 2 month clinic visits using Audio Computer-Assisted Self-Interviews (ACASI) on a password protected laptop.

Lab values and clinical information will be obtained through medical records review and adherence information from pill counts and pharmacy records.

Inclusion Criteria:

• Confirmed diagnosis of SCD (any genotype)
• Ages 12.0 - 17.99 at time of study enrollment
• Stable HU dose composed of only one capsule strength prescribed in pill formulation for ≥ 6 months without documented hematological toxicity (excluding dose adjustments for weight gain)
• Lives with their legal guardian
• Anticipated to return to clinic at proposed 4-week intervals

Exclusion Criteria:

• Primary caregiver and/or youth unable to understand English and/or youth not cognitively intact (known IQ < 70) such that the study questionnaire cannot be understood and completed.
• Participant unable to complete the questionnaires due to refusal or current acute illness (e.g., pain crisis).
• Inability or unwillingness of research participant or legal guardian/representative to give written informed consent.

Participants ages 12.0-17.99 with Sickle cell disease any genotype and their caregivers