The evidence base described here had significant limitations. Most notably, only two randomized trials addressed hydroxyurea efficacy and safety in patients with sickle cell disease. While the trial enrolling adults was a high-quality trial, it was not long, with only 2 years elapsing since randomization. Two years may be adequate for assessing short-term efficacy, but we had no trial data that made it possible to comment on the long-term efficacy of the drug. We also found no trial data to allow us to assess the effectiveness of this drug in a population who may be asked to take the.
