Hydroxyurea for hemoglobin E/β-thalassemia: a systematic review and meta-analysis.

Hemoglobin E-beta thalassemia (Hb E/β-thalassemia) is a distinct, yet common, type of β-thalassemia, in which the patient co-inherits a β-thalassemia allele from one parent, and a structural variant, Hb E, from the other parent. This co-inheritance leads to remarkable clinical heterogeneity, varying degrees of chronic anemia, and a wide spectrum of complications due to ineffective erythropoiesis and iron overload. Hydroxyurea (HU), an oral chemotherapeutic drug, is expected to decrease disease severity. To assess the clinical efficacy and safety of HU in Hb E/β-thalassemia patients. We searched MEDLINE, EMBASE, Cochrane databases, and major preceding conferences for studies that assessed HU in Hb E/β-thalassemias patients. The effect size was estimated as a proportion (responder/sample size). Qualities of eligible studies were assessed using NIH tools. A total of five [one randomized clinical trial (RCT) and four observational] studies involving 106 patients were included. HU was associated with a significant RR of 46% with no statistical heterogeneity. No serious adverse effects were reported. Patients with Hb E/β-thalassemia may benefit from a trial of HU, though large RCTs assessing efficacy should be conducted to confirm the findings of this meta-analysis and to assess long-term toxicity and response sustainability.