Please assess the completion status of the following clinical trial:

Trial Title: European Sickle Cell Disease Cohort - Hydroxyurea

Study Design Characteristics:
- Allocation: None
- Intervention Model: None
- Observational Model: COHORT
- Primary Purpose: None
- Time Perspective: PROSPECTIVE
- Masking: None
- Phase: None
- Number of Arms: None

Eligibility Criteria:
Inclusion Criteria:~* Male or female ambulatory patients, aged 2 years and more (children, adolescents or adults)~* With symptomatic sickle cell syndrome~* Treated with Siklos®~* Having been informed of the study by the initiating physician and consenting to participate to the cohort.

- Gender: ALL
- Minimum Age: 2 Years
- Maximum Age: None
- Healthy Volunteers: f

Based on this trial design, predict the completion outcome and termination type (if applicable).