A randomised study of the effect of two doses of biosynthetic human growth hormone on final height of children with familial short stature

GH and IGF-1 Replacement in Children

In this chapter, we want to give an overview on what we have learned from more than 30 years ago on the use of recombinant human growth hormone (rhGH) and later recombinant human IGF-1 which was introduced for the treatment of short children and what are the safety issues concerned with this treatment. However, rhGH is used not solely in conditions where short stature is the consequence of GH deficiency but also in various disorders without a proven GH deficiency. In clinical studies, growth responses to various forms of rhGH therapy were analyzed, adding to our concept about the physiology of growth. Most patients under rhGH treatment show a considerable short-term effect; however, the long-term gain of height in a child obtained by a year-long treatment until final height remains controversial in some of the growth disorders that have been treated with rhGH or IGF-1. Today the first studies on the long-term safety of rhGH treatment have been published and raising some questions whether this treatment is similarly safe for all the patient groups treated with rhGH. Although there is a long-standing safety record for these hormone replacement therapies, in the face of the considerable costs involved, the discussion about the risk to benefit ratio is continuing. Newer developments of rhGH treatment include long-term preparations, which have only to be injected once a week. Although some of these drugs already have proven their non-inferiority to conventional rhGH treatment, we have to await further results to see whether they show improvements in treatment adherence of the patients and prove their long-term safety.

The Effect of Recombinant Growth Hormone Treatment in Children with Idiopathic Short Stature and Low Insulin-Like Growth Factor-1 Levels

OBJECTIVE

Idiopathic short stature (ISS) constitutes a heterogeneous group of short stature which is not associated with an endocrine or other identifiable cause. Some ISS patients may have varying degrees of insulin-like growth factor-1 (IGF-1) deficiency. Recombinant growth hormone (rGH) treatment has been used by some authors with variable results. Reports on long-term rGH treatment are limited.

METHODS

In this study, 21 slowly growing, non-GH-deficient ISS children who received rGH treatment for 3.62±0.92 years were evaluated at the end of a 5.42±1.67-year follow-up period. The study group included patients with low IGF-1 levels who also responded well to an IGF generation test. The patients were divided into two groups as good responders [height increment >1 standard deviation (SD)] and poor responders (height increment <1 SD) at the end of the follow-up period.

RESULTS

The height of the patients improved from -3.16±0.46 SD score (SDS) to -1.9±0.66 SDS. At the end of the follow-up period, mean height SDS was -1.72. Eleven of the patients showed a good response to treatment. Clinical parameters were essentially similar in the good responders and the poor responders groups. A female preponderance was noted in the good responders group.

CONCLUSION

rGH treatment can safely be used in ISS children. Long-term GH treatment will ameliorate the height deficit and almost 40% of patients may reach their target height.

Revaluation of the clinical and metabolic behavior of children with isolated growth hormone deficiency during GH treatment according to newly proposed note 39 of the Italian Medicines Agency (AIFA)

PURPOSE

This study aimed at evaluating the clinical and metabolic behavior of children with isolated growth hormone (GH)-deficiency (GHD), grouped according to the new AIFA criteria for the appropriateness of use and reimbursement of GH treatment in children.

METHODS

The clinical and metabolic data of 310 prepubertal children (220 M, 90 F; mean age 10.8 years) grouped, according to new AIFA note 39, into Group A (No. 181 with a peak of GH <8 µg/l), Group B (No. 103 with a peak of GH ≥8 and <10 µg/l) and Group C (No. 26 with a peak of GH >10 µg/l) were retrospectively analyzed. Group A and B, diagnosed as having GHD, were treated with GH for at least 24 months, while Group C was analyzed only at baseline.

RESULTS

At baseline, Group A showed higher waist circumference than B (p = 0.031) and C (p = 0.041), while no difference in metabolic parameters was found between the three groups. After 12 and 24 months of treatment, Group B showed lower height velocity (p < 0.001 and p = 0.049, respectively) than Group A. As regards the metabolic parameters, both after 12 and 24 months of treatment, in Group B we found higher fasting glucose (p < 0.001 and p = 0.020), insulin (p = 0.002 and p = 0.011), Homa-β (p = 0.020 and p = 0.015) and Homa-IR (both p = 0.001) than Group A, with concomitant lower QUICKI (both p < 0.001) and HDL cholesterol (p = 0.020 and p = 0.011), without difference in other lipid parameters. The HbA1c levels, although always within the normal range, were found higher in Group B than Group A after 12 months (p = 0.015).

CONCLUSIONS

According to the new AIFA criteria, the reduction of GH cut-off for GHD diagnosis can be supported by auxological and metabolic data. The real benefits from GH therapy in children with higher stimulated GH levels at diagnosis remains to be better understand.

Hormone replacement therapy in children: The use of growth hormone and IGF-I

Recombinant human GH (rhGH) has been available since 1985. This article gives an overview, what has been achieved over the past 30 years in respect to optimization of rhGH treatment for the individual child with GH deficiency and what are the safety issues concerned with this treatment. In the last twenty years significant scientific progress has been made in the diagnosis of GH deficiency, the genetic disorders that are associated with pituitary GH deficiency and the genetics that influence growth in general. On the other hand rhGH is not only used in states of GH deficiency but also various conditions without a proven GH deficiency by classical standards. Clinical studies that investigated both the genetics of growth and the individual responses to rhGH therapy in these patient populations were able to refine our concept about the physiology of normal growth. In most patients under rhGH treatment there is a considerable short-term effect, however the overall gain in growth obtained by a long-term treatment until final height still remains a matter of debate in some of the conditions treated. Also first studies on the long-term safety risks of rhGH treatment have raised the question whether this treatment is similarly safe for all the patient groups eligible for such a treatment. Therefore even in the face of a longstanding safety record of this drug replacement therapy the discussion about the right cost and risk to benefit ratio is continuing. Consequently there is still a need for carefully conducted long-term studies that use modern anthropometric, genetic, and laboratory techniques in order to provide the necessary information for clinicians to select the patients that will benefit best from this valuable treatment without any long term risk.

Clinical review: Lessons learned from the hGH era

Today, many medical interventions that begin as treatments for disease often expand into therapies that reduce disability, lessen disadvantage, or even confer advantage. Forces that propel profitable drugs, devices, and procedures dominate over considerations of efficient and equitable distribution of resources. This dominance is fueled by industry-physician collaborations often biased by prior assumptions, reliant on surrogate outcomes, and advantageous to marketing. Interventions are justified by "medicalization" of physiologic variations (e.g. short stature) as defects or disease, and nudged into "standard practice" by key opinion leaders. The story below of recombinant human growth hormone (hGH) treatment of short stature is one vivid example, but others (e.g. expansion of drug treatment to "optimize" cholesterol profiles, bone health, psychological well-being) can be found throughout medicine. In the new obesity era, lessons learned from the hGH era will be needed to keep the field of pediatric endocrinology empowered to make the key clinical decisions, and free of unintended consequences for patients and runaway health care inflation for society.

Update in growth hormone therapy of children

Although recombinant human GH (rhGH) has been available since 1985, there are several questions related to its use that remain unanswered. The Entrez-PubMed search engine was used to conduct a review of publications appearing since 2007 that address growth and GH treatment. Recent publications related to the diagnosis of GH deficiency, genetics of growth, the use of rhGH in different genetic conditions, in idiopathic short stature, and in puberty, and strategies to adjust rhGH dose were reviewed. New studies investigating the genetics of growth and the response to rhGH therapy in different groups are helping in the understanding of the physiology of normal growth. Although in most children treated with rhGH there is a short-term benefit, the clinical relevance of the benefits after long-term treatment in some conditions remains unclear. The challenges are to define milder forms of GH deficiency and to assess the relevance of the benefits, if any, caused by rhGH in different patient populations and the best therapeutic approach for these patients. Well-designed long-term studies using anthropometric, genetic, and laboratory data that will also assess long-term quality of life benefits are needed to help clinicians select patients to initiate treatment with rhGH and to adjust treatment to improve outcome.