Pooled analysis of the 7 studies documenting TCD measurements before and after hydroxyurea therapy in children with SCA. The pooled analysis is based on the random-effect model demonstrating the average decrease in TCD measurement after starting hydroxyurea therapy of 25 cm/s (left panel). The table also includes the observation that the decrease in TCD measurements can occur as early as 3 months after starting hydroxyurea therapy, with a sustained impact of hydroxyurea therapy on decreasing TCD measurements for ≥36 months. The black diamond represents the results of random-effect models (right panel). The tips of the diamond represent the 95% confidence interval (CI) of the meta-analyses for the random-effect models. MTD, maximum tolerated dose. Reprinted from DeBaun and Kirkham.⁶