Hydroxyurea for β-Thalassemia Major: A Meta-Analysis

Background

β-thalassemia major (β-TM) is one of the most common inherited diseases worldwide, characterized by a reduced ability to produce hemoglobin resulting in life-long transfusion-dependent anemia. Chronic transfusions carry significant risks such as infection, and result in iron overload that can cause significant multisystem organ damage. Hydroxyurea, an oral chemotherapeutic drug, is anticipated to decrease the need for transfusions, either completely or partially by raising hemoglobin levels and thus decreasing the short and long term complications of chronic transfusions.

Objectives

To evaluate the clinical efficacy and safety of hydroxyurea in β-thalassemia major (β-TM) patients of any age.

Search strategy

We searched MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), ongoing trials registers, and major preceding conferences. Hand searches were also conducted using reference lists from primary studies. All searches were updated to June 5, 2014.

Selection criteria

Randomized controlled trials (RCTs) and observational studies (sample size ≥ 5) assessing the clinical efficacy of hydroxyurea alone for three months or longer, for the treatment of patients with β-TM were included.

Data collection and analysis

Two authors acted as reviewers and independently assessed study quality and extracted data from the included studies. Authors of included studies were contacted if further information was required. β-TM includes the classical β-TM as well as severe hemoglobin E/β thalassemia, both of which are characterized by lifelong transfusion needs. The effect size was estimated as a proportion (those showing response to treatment over the total number treated) and reported as overall response rate (ORR) or complete response rate (CRR). ORR was defined as ≥ 50% reduction in transfusion need and CRR was defined as complete cessation of regular transfusion. All data was analyzed using Stata, Version 13.0.

Results

A total of 10 observational studies involving 620 patients were included. Hydroxyurea was associated with a statistically significant decrease in transfusion need with CRR of 36% (95% CI, 23-50%) and ORR of 66% (95% CI, 52-79%).

All of the studies had several limitations, such as small sample size, lack of comparison group, under-reporting of data and methods, and being observational studies.

Adverse events (AEs) were transient and improved with temporary cessation of the drug and/or adjustment of the dose. No long-term AEs, including cancer or end organ damage were reported.

Authors’ conclusion

Hydroxyurea appears to be effective in the management of β-TM by decreasing the need for chronic blood transfusions completely or partially in a significant number of patients. It appears to be well tolerated and associated with mild and transient AEs. Patients with β-TM may benefit from a trial of hydroxyurea, though large RCTs assessing efficacy should be done to confirm the findings of this meta-analysis.