Kaplan–Meier curve of disease-modifying therapy for the cohort of children and adults with SCA. A Kaplan–Meier curve was constructed to evaluate the different treatments. Treatment groups were mutually exclusive and in a hierarchical order: HSCT (n = 22) > regular blood transfusion for at least 2 years (n = 56) > hydroxyurea for at least 1 year (n = 243) > no disease-modifying therapy (n = 98).