OBJECTIVES: To assess the effectiveness, safety and appropriate dose regimen of hydroxyurea in people with non-transfusion dependent beta thalassaemia (haemoglobin E combined with beta thalassaemia and beta thalassaemia intermedia).
SEARCH METHODS: We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Haemoglobinopathies Trials Register, compiled from electronic database searches and handsearching of relevant journals. We also searched ongoing trials registries and the reference lists of relevant articles and reviews.Date of last search: 30 April 2016.
SELECTION CRITERIA: Randomised or quasi-randomised controlled trials of hydroxyurea in people with non-transfusion dependent beta thalassaemia comparing hydroxyurea with placebo or standard treatment or comparing different doses of hydroxyurea.
DATA COLLECTION AND ANALYSIS: Two authors independently applied the inclusion criteria in order to select trials for inclusion. Both authors assessed the risk of bias of trials and extracted the data. A third author verified these assessments.
MAIN RESULTS: No trials comparing hydroxyurea with placebo or standard care were found. However, we included one randomised controlled trial (n = 61) comparing 20 mg/kg/day with 10 mg/kg/day of hydroxyurea for 24 weeks.Both haemoglobin and foetal haemoglobin levels were lower at 24 weeks in the 20 mg group compared with the 10 mg group, mean difference -2.39 (95% confidence interval - 2.8 to -1.98) and mean difference -1.5 (95% confidence interval -1.83 to -1.17), respectively. Major adverse effects were significantly more common in the 20 mg group, for neutropenia risk ratio 9.93 (95% confidence interval 1.34 to 73.97) and for thrombocytopenia risk ratio 3.68 (95% confidence interval 1.13 to 12.07). No difference was reported for minor adverse effects (gastrointestinal disturbances and raised liver enzymes). The effect of hydroxyurea on transfusion frequency was not reported.The overall quality for the outcomes reported was graded as very low mainly because the outcomes were derived from only one small study with an unclear method of allocation concealment.
AUTHORS' CONCLUSIONS: There is no evidence from randomised controlled trials to show whether hydroxyurea has any effect compared with controls on the need for blood transfusion. Administration of 10 mg/kg/day compared to 20 mg/kg/day of hydroxyurea resulted in higher haemoglobin levels and seems safer with fewer adverse effects. It has not been reported whether hydroxyurea is capable of reducing the need for blood transfusion. Large well-designed randomised controlled trials with sufficient duration of follow up are recommended.
METHODS: The Filipino β-deletion was identified using gap-polymerase chain reaction (PCR) in the parents of transfusion dependent β-thalassaemia patients who were homozygous for the Filipino β-deletion in the indigenous population of Sabah, Malaysia. Hb subtypes were quantified on the BioRad Variant II Hb analyser. Concurrent α-thalassaemia was identified by multiplex gap-PCR for deletions and amplification refractory mutation system (ARMS)-PCR for non-deletional mutations.
RESULTS: The mean HbA2 level for Filipino β-thalassaemia trait was 5.9 ± 0.47 and with coinheritance of α-thalassaemia was 6.3 ± 0.44 (-α heterozygous) and 6.7 ± 0.36 (-α homozygous). The HbA2 levels were all >4% in keeping with the findings of classical β-thalassaemia trait and significantly higher than levels seen in non-deletional forms of β-thalassaemia.
CONCLUSION: The HbA2 level measured on the BioRad Variant II Hb analyser was lower than the level in the first description of the Filipino β-thalassaemia. β-thalassaemia trait with coinheritance of α-thalassaemia (-α) is associated with significantly higher HbA2 level.
METHODS: This is a prospective case-control study. We registered 80 patients and 60 healthy controls from Jan 2009 to Dec 2013. Complete blood counts, prothrombin time, activated partial thromboplastin time, protein C, protein S, antithrombin, serum ferritin, liver enzymes; HbsAg and Anti- HCV were evaluated.
RESULT: There were 42 males and 38 females with mean age of 12.30±5.50 years. The mean protein C, protein S and antithrombin in patients and control were 58.25±22.5 versus 110.67±22.60, 67.90±19.58 versus 98.70±21.54 and 89.73±18.09 versus 104.0±10.98 (p<0.001) respectively. Protein C was predominantly deficient in 65% followed by protein S and antithrombin in 35% and 20% respectively. Protein C deficiency divulged positive correlation with protein S deficiency (p = 0.035) and antithrombin deficiency with hemoglobin of ≤8gm% (p<0.0025). No significant correlation of prothrombotic markers was established with maternal characteristics, hepatic dysfunction, hepatitis and serum ferritin.
CONCLUSION: Substantial decrement in prothrombotic markers, primarily protein C, may be implicated in elevated thrombosis; however follow-up data is required to establish definitive thromboembolic events.