The overarching goal of this proposal is to identify modifiable behavioral strategies based on patient-reported outcomes (PROs) and health-related quality of life (HRQOL) that will improve hydroxyurea (HU) adherence among adolescents and young adults with sickle cell disease (SCD). In this proposed study, we intend to test the functionality of a PROs-toolbox feature, which will be integrated into our existing smartphone application platform (SCD-app), over a 24-week period in a cohort of SCD patients and their caregivers.

Adherence to hydroxyurea is a multi-factorial dynamic process, and, to date, predictors for changes in adherence levels over time remain unclear. Changes in HRQOL data could serve as surrogate markers for changes in hydroxyurea adherence over time, and could suggest when patients might or might not need or benefit from an intervention based on worse or better HRQOL scores, respectively.

The main hypothesis of this study is that the assessment of patients' HRQOL at home using a SCD smartphone application platform (app) is feasible and acceptable, and that less frequent assessments of HRQOL at home will have an overall higher completion rate when compared to more frequent ones. We plan to assess HRQOL using the NIH-developed patient reported outcomes measurement information system (PROMIS®) with computerized adaptive testing (CAT) approach. PROMIS®-CAT approach is a reliable and valid PROs assessment platform that has been used in limited studies in SCD.

The study will include the following specific aims:

1. To evaluate the feasibility and acceptability of the assessment of patients HRQOL at home using smartphones with PROMIS®-CAT measures integrated into a SCD-app.
2. To examine the effect of the frequency of required HRQOL assessments on participants' completion rate over 24-week period with HRQOL evaluated every 2 weeks (Group 1) versus every 4 weeks (Group 2).
3. To explore participants' experience and preferences with the process and the frequency of HRQOL assessment at home using their smartphones with PROMIS®-CAT measures integrated into a SCD-app.

Inclusion Criteria:

• Age 12 years or older at the time of study enrollment;
• SCD diagnosis (all genotypes) confirmed by hemoglobin electrophoresis;
• Own or have access to a smartphone or a tablet; and
• Speak and read English.

Exclusion Criteria:

• Patients or caregivers with cognitive impairment;
• Patients or caregivers physical impairment; and
• Patients or caregivers who will not be able to complete study assessments.

All study data are de-identified and will be analysed as aggregate.