Growth hormone therapy for people with thalassaemia

Abstract

Background: Thalassaemia is a recessively-inherited blood disorder that leads to anaemia of varying severity. In those affected by the more severe forms, regular blood transfusions are required which may lead to iron overload. Accumulated iron from blood transfusions may be deposited in vital organs including the heart, liver and endocrine organs such as the pituitary glands which can affect growth hormone production. Growth hormone deficiency is one of the factors that can lead to short stature, a common complication in people with thalassaemia. Growth hormone replacement therapy has been used in children with thalassaemia who have short stature and growth hormone deficiency.

Objectives: To assess the benefits and safety of growth hormone therapy in people with thalassaemia.

Search methods: We searched the Cochrane Haemoglobinopathies Trials Register, compiled from electronic database searches and handsearching of journals and conference abstract books. We also searched the reference lists of relevant articles, reviews and clinical trial registries. Our database and trial registry searches are current to 10 August 2017 and 08 August 2017, respectively.

Selection criteria: Randomised and quasi-randomised controlled trials comparing the use of growth hormone therapy to placebo or standard care in people with thalassaemia of any type or severity.

Data collection and analysis: Two authors independently selected trials for inclusion. Data extraction and assessment of risk of bias were also conducted independently by two authors. The quality of the evidence was assessed using GRADE criteria.

Main results: One parallel trial conducted in Turkey was included. The trial recruited 20 children with homozygous beta thalassaemia who had short stature; 10 children received growth hormone therapy administered subcutaneously on a daily basis at a dose of 0.7 IU/kg per week and 10 children received standard care. The overall risk of bias in this trial was low except for the selection criteria and attrition bias which were unclear. The quality of the evidence for all major outcomes was moderate, the main concern was imprecision of the estimates due to the small sample size leading to wide confidence intervals. Final height (cm) (the review's pre-specified primary outcome) and change in height were not assessed in the included trial. The trial reported no clear difference between groups in height standard deviation (SD) score after one year, mean difference (MD) -0.09 (95% confidence interval (CI) -0.33 to 0.15 (moderate quality evidence). However, modest improvements appeared to be observed in the following key outcomes in children receiving growth hormone therapy compared to control (moderate quality evidence): change between baseline and final visit in height SD score, MD 0.26 (95% CI 0.13 to 0.39); height velocity, MD 2.28 cm/year (95% CI 1.76 to 2.80); height velocity SD score, MD 3.31 (95% CI 2.43 to 4.19); and change in height velocity SD score between baseline and final visit, MD 3.41 (95% CI 2.45 to 4.37). No adverse effects of treatment were reported in either group; however, while there was no clear difference between groups in the oral glucose tolerance test at one year, fasting blood glucose was significantly higher in the growth hormone therapy group compared to control, although both results were still within the normal range, MD 6.67 mg/dL (95% CI 2.66 to 10.68). There were no data beyond the one-year trial period.

Authors' conclusions: A small single trial contributed evidence of moderate quality that the use of growth hormone for a year may improve height velocity of children with thalassaemia although height SD score in the treatment group was similar to the control group. There are no randomised controlled trials in adults or trials that address the use of growth hormone therapy over a longer period and assess its effect on final height and quality of life. The optimal dosage of growth hormone and the ideal time to start this therapy remain uncertain. Large well-designed randomised controlled trials over a longer period with sufficient duration of follow up are needed.

Figure 1

Study flow diagram.

Analysis 1.1

Comparison 1 Growth hormone versus control, Outcome 1 Oral glucose tolerance test sum (mg/dL).

Analysis 1.2

Comparison 1 Growth hormone versus control, Outcome 2 Fasting blood glucose (mg/dL).

Analysis 1.3

Comparison 1 Growth hormone versus control, Outcome 3 Height SD score.

Analysis 1.4

Comparison 1 Growth hormone versus control, Outcome 4 Change from baseline in height SD score.

Analysis 1.5

Comparison 1 Growth hormone versus control, Outcome 5 Height velocity (cm/year).

Analysis 1.6

Comparison 1 Growth hormone versus control, Outcome 6 Height velocity SD score.

Analysis 1.7

Comparison 1 Growth hormone versus control, Outcome 7 Change from baseline in height velocity SD score.

Analysis 1.8

Comparison 1 Growth hormone versus control, Outcome 8 Serum insulin‐like growth hormone (IGF‐1) (ng/mL).