Only two studies investigated barriers to use of HU. Perceived efficacy and perceived safety of HU had the largest influence on patients' (or parents' ) choice to use HU. Providers reported barriers to be patient concerns about side effects; and their own concerns about HU in older patients, patient compliance, lack of contraception, side effects and carcinogenic potential, doubts about effectiveness, and concern about costs. Conclusions. HU is efficacious in children and adults with SCD; with an increase in Hb F%, and reduction in hospitalizations and pain crises. However, few studies have measured the effectiveness of HU for.
