Prevalence of TRV ≥2.5 m/s at baseline and at 2-year follow-up evaluation. Proportion of participants with elevated TRV (≥2.5 m/s) in the entire cohort and within each subgroup at baseline and 2-year follow-up evaluation. Group 1: not on DMT at baseline or 2-year evaluation; group 2: not on DMT at baseline evaluation, but started on hydroxyurea prior to the 2-year evaluation; group 3: on hydroxyurea at baseline and at 2-year evaluation; group 4: on monthly blood transfusion at baseline and at 2-year evaluation. NS, not significant.