Hydroxyurea for nontransfusion-dependent ß-thalassemia: A systematic review and meta-analysis.

OBJECTIVE/BACKGROUND: Nontransfusion-dependent ß-thalassemia (NTDßT) syndromes consist of ß-thalassemia intermedia and moderate hemoglobin E/ß thalassemias. They are characterized by varying degrees of chronic anemia and a wide spectrum of complications due to ineffective erythropoiesis and iron overload from chronic transfusions. Hydroxyurea (HU), an oral chemotherapeutic drug, is anticipated to decrease disease severity. METHODS: We performed a meta-analysis to evaluate the clinical efficacy and safety of HU in NTDßT patients of any age. MEDLINE, EMBASE, Cochrane databases, and major conference proceedings for studies that assessed HU in NTDßT patients were searched. Qualities of eligible studies were assessed by National Institutes of Health tools. RESULTS: Seventeen studies, collectively involving 709 patients, fulfilled the eligibility criteria. HU was associated with a significant decrease in transfusion need in severe NTDßT with complete and overall (≥50%) response rates of 42% and 79%, respectively. For mild NTDßT, HU was effective in raising hemoglobin by 1g/L in 64% of patients. CONCLUSION: HU appears to be effective, well tolerated, and associated with mild and transient adverse events. NTDßT patients may benefit from a trial of HU, although large randomized clinical trials assessing its efficacy should be conducted to confirm the findings of this meta-analysis and to assess its long-term toxicity and response sustainability.