Growth response to an individualized versus fixed dose GH treatment in short children born small for gestational age: the OPTIMA study

Growth response to growth hormone treatment in patients with SHOX deficiency can be predicted by the Cologne prediction model

Background Growth hormone (GH) treatment in children with short stature homeobox-containing gene (SHOX) deficiency is recognized to increase height velocity (HV) and adult height. Prediction of growth response continues to be a challenge. A comparatively accurate method is the Cologne prediction model developed in children with GH deficiency. The aim was to investigate whether this model also applies to patients with SHOX deficiency. Methods Included were 48 patients with SHOX deficiency confirmed by DNA analysis and treated with 0.05 mg/kg/day of somatropin. Prediction by the Cologne model uses the following variables: relative bone age (BA) retardation, baseline insulin-like growth factor-I (IGF-I), urinary deoxypyridinoline (DPD) cross-links at 4 weeks and HV at 3 months. Results HV and height standard deviation scores (SDS) increased significantly during the first year of treatment. Predicted and observed HV (cm/year) showed a Pearson correlation coefficient of 0.50 (p<0.001; root-mean-square error=1.63) and for first-year change in height SDS a Pearson correlation coefficient of 0.751 (p<0.001; root-mean-square error=0.32). Poor response could be adequately predicted using SDS change, with sensitivity and specificity both above 70% for certain thresholds.

CONCLUSIONS

The results demonstrate that the Cologne model can be used to predict growth response in patients with SHOX deficiency with reasonable precision in the first treatment year, comparable to prediction in patients with GH deficiency.

Does the GH/IGF-1 axis contribute to skeletal sexual dimorphism? Evidence from mouse studies

The contribution of the gonadotropic axis to skeletal sexual dimorphism (SSD) was clarified in recent years. Studies with animal models of estrogen receptor (ER) or androgen receptor (AR) null mice, as well as mice with bone cell-specific ablation of ER or AR, revealed that both hormones play major roles in skeletal acquisition, and that estrogen regulates skeletal accrual in both sexes. The growth hormone (GH) and its downstream effector, the insulin-like growth factor-1 (IGF-1) are also major determinants of peak bone mass during puberty and young adulthood, and play important roles in maintaining bone integrity during aging. A few studies in both humans and animal models suggest that in addition to the differences in sex steroid actions on bone, sex-specific effects of GH and IGF-1 play essential roles in SSD. However, the contributions of the somatotropic (GH/IGF-1) axis to SSD are controversial and data is difficult to interpret. GH/IGF-1 are pleotropic hormones that act in an endocrine and autocrine/paracrine fashion on multiple tissues, affecting body composition as well as metabolism. Thus, understanding the contribution of the somatotropic axis to SSD requires the use of mouse models that will differentiate between these two modes of action. Elucidation of the relative contribution of GH/IGF-1 axis to SSD is significant because GH is approved for the treatment of normal children with short stature and children with congenital growth disorders. Thus, if the GH/IGF-1 axis determines SSD, treatment with GH may be tailored according to sex. In the following review, we give an overview of the roles of sex steroids in determining SSD and how they may interact with the GH/IGF-1 axis in bone. We summarize several mouse models with impaired somatotropic axis and speculate on the possible contribution of that axis to SSD.

Height, muscle, fat and bone response to growth hormone in short children with very low birth weight born appropriate for gestational age and small for gestational age

BACKGROUND/AIMS

Growth hormone (GH) treatment is approved for short children born SGA but not for AGA. Our aim was to study the effect of GH in short VLBW SGA and AGA children.

METHODS

The study group comprised 44 prepubertal short children with a birth weight <1,500 g: 27 AGA (12 females) and 17 SGA (6 females). Mean values at GH start were (AGA, SGA): age 6.94, 7.14 years, height standard deviation score (SDS) -3.33, -3.33, and GH dose (mean ± SD) 54 ± 12, 51 ± 11 µg/kg/day. Arm and calf cross-sectional muscle area using peripheral quantitative computer tomography, body composition data using dual-energy X-ray absorptiometry and body impedance assessment, maximal isometric grip force and skin fold thickness, IGF-1 and IGFBP-3 were measured at the start and after 12 months of GH.

RESULTS

At GH start, both groups had similar characteristics with low height, weight, height velocity, muscle mass, bone thickness and content. The first year of GH treatment led to changes in muscle area SDS (AGA, SGA) -2.23 to -0.73 (p = 0.0010), -3.18 to -1.17 (p = 0.060) (AGA vs. SGA p = 0.61), fat area SDS -1.06 to -1.83 (p = 0.054), -0.62 to -1.75 (p = 0.12) (AGA vs. SGA p = 0.65) and height velocity SDS -0.0015 to 4.2 (p < 0.0001), -0.18 to 3.3 (p < 0.0001) (AGA vs. SGA p = 0.36).

CONCLUSIONS

Growth, muscle and fat mass are similarly impaired in short prepubertal AGA and SGA VLBW children. The children born AGA show a similar or better response to GH compared to those born SGA. These results reveal the arbitrary nature of using the criterion 'SGA' for eligibility to GH treatment in children born with a birth weight <1,500 g.

Comparison of weight- vs body surface area-based growth hormone dosing for children: implications for response

OBJECTIVE

To compare weight (per kg)- vs body surface area (BSA, per m(2) )-based growth hormone (GH) dosing formats in children and to derive a useful conversion formula between the two formats.

PATIENTS AND DESIGN

Growth hormone doses (>33,000) from 1874 children were obtained from the national Australian database (OZGROW) and used to derive conversion formulae and to confirm the accuracy of a conversion formula based on a weight-only BSA estimate. A further 27,000 doses were used to test the accuracy of all formulae. The best conversion formula was used to compare weight- and surface area-based GH dosing, which included an analysis of first year response (∆SDS height or growth velocity, GV).

MEASUREMENTS

Growth hormone doses in mg/m(2) /wk and mg/kg/wk, dose estimates, residuals, first year ∆SDS, first year GV.

RESULTS

The formula, [Formula: see text] based on a weight-only BSA estimate, provides accurate dose conversion (mean residual, 0·005 mg/kg/week). A constant mg/m(2) /week dose expressed in terms of mg/kg/week declines quickly with increasing body weight to approximately 15 kg after which the decline continues although less dramatically. For Australian patients, despite an increase in mean per m(2) dose with increased starting weight/age, the per kg dose decreased. This was associated with a greater decline in first year GV than estimated if a per kg dose had been maintained.

CONCLUSIONS

Growth hormone doses can be accurately converted between formats. Surface area-based GH dosing is likely to result in a reduced height response as children become heavier when compared with weight-based GH dosing.

Personalized approach to growth hormone treatment: clinical use of growth prediction models

The goal of growth hormone (GH) treatment in a short child is to attain a fast catch-up growth toward the target height (TH) standard deviation score (SDS), followed by a maintenance phase, a proper pubertal height gain, and an adult height close to TH. The short-term response variable of GH treatment, first-year height velocity (HV) (cm/year or change in height SDS), can either be compared with GH response charts for diagnosis, age and gender, or with predicted HV based on prediction models. Three types of prediction models have been described: the Kabi International Growth Hormone Study models, the Gothenburg models and the Cologne model. With these models, 50-80% of the variance could be explained. When used prospectively, individualized dosing reduces the variation in growth response in comparison with a fixed dose per body weight. Insulin-like growth factor-I-based dose titration also led to a decrease in the variation. It is uncertain whether adding biochemical, genetic or proteomic markers may improve the accuracy of the prediction. Prediction models may lead to a more evidence-based approach to determine the GH dose regimen and may reduce the drug costs for GH treatment. There is a need for user-friendly software programs to make prediction models easily available in the clinic.

Computerized advice on drug dosage to improve prescribing practice

BACKGROUND

Maintaining therapeutic concentrations of drugs with a narrow therapeutic window is a complex task. Several computer systems have been designed to help doctors determine optimum drug dosage. Significant improvements in health care could be achieved if computer advice improved health outcomes and could be implemented in routine practice in a cost-effective fashion. This is an updated version of an earlier Cochrane systematic review, first published in 2001 and updated in 2008.

OBJECTIVES

To assess whether computerized advice on drug dosage has beneficial effects on patient outcomes compared with routine care (empiric dosing without computer assistance).

SEARCH METHODS

The following databases were searched from 1996 to January 2012: EPOC Group Specialized Register, Reference Manager; Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Ovid; EMBASE, Ovid; and CINAHL, EbscoHost. A "top up" search was conducted for the period January 2012 to January 2013; these results were screened by the authors and potentially relevant studies are listed in Studies Awaiting Classification. The review authors also searched reference lists of relevant studies and related reviews.

SELECTION CRITERIA

We included randomized controlled trials, non-randomized controlled trials, controlled before-and-after studies and interrupted time series analyses of computerized advice on drug dosage. The participants were healthcare professionals responsible for patient care. The outcomes were any objectively measured change in the health of patients resulting from computerized advice (such as therapeutic drug control, clinical improvement, adverse reactions).

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed study quality. We grouped the results from the included studies by drug used and the effect aimed at for aminoglycoside antibiotics, amitriptyline, anaesthetics, insulin, anticoagulants, ovarian stimulation, anti-rejection drugs and theophylline. We combined the effect sizes to give an overall effect for each subgroup of studies, using a random-effects model. We further grouped studies by type of outcome when appropriate (i.e. no evidence of heterogeneity).

MAIN RESULTS

Forty-six comparisons (from 42 trials) were included (as compared with 26 comparisons in the last update) including a wide range of drugs in inpatient and outpatient settings. All were randomized controlled trials except two studies. Interventions usually targeted doctors, although some studies attempted to influence prescriptions by pharmacists and nurses. Drugs evaluated were anticoagulants, insulin, aminoglycoside antibiotics, theophylline, anti-rejection drugs, anaesthetic agents, antidepressants and gonadotropins. Although all studies used reliable outcome measures, their quality was generally low.This update found similar results to the previous update and managed to identify specific therapeutic areas where the computerized advice on drug dosage was beneficial compared with routine care:1. it increased target peak serum concentrations (standardized mean difference (SMD) 0.79, 95% CI 0.46 to 1.13) and the proportion of people with plasma drug concentrations within the therapeutic range after two days (pooled risk ratio (RR) 4.44, 95% CI 1.94 to 10.13) for aminoglycoside antibiotics;2. it led to a physiological parameter more often within the desired range for oral anticoagulants (SMD for percentage of time spent in target international normalized ratio +0.19, 95% CI 0.06 to 0.33) and insulin (SMD for percentage of time in target glucose range: +1.27, 95% CI 0.56 to 1.98);3. it decreased the time to achieve stabilization for oral anticoagulants (SMD -0.56, 95% CI -1.07 to -0.04);4. it decreased the thromboembolism events (rate ratio 0.68, 95% CI 0.49 to 0.94) and tended to decrease bleeding events for anticoagulants although the difference was not significant (rate ratio 0.81, 95% CI 0.60 to 1.08). It tended to decrease unwanted effects for aminoglycoside antibiotics (nephrotoxicity: RR 0.67, 95% CI 0.42 to 1.06) and anti-rejection drugs (cytomegalovirus infections: RR 0.90, 95% CI 0.58 to 1.40);5. it tended to reduce the length of time spent in the hospital although the difference was not significant (SMD -0.15, 95% CI -0.33 to 0.02) and to achieve comparable or better cost-effectiveness ratios than usual care;6. there was no evidence of differences in mortality or other clinical adverse events for insulin (hypoglycaemia), anaesthetic agents, anti-rejection drugs and antidepressants.For all outcomes, statistical heterogeneity quantified by I(2) statistics was moderate to high.

AUTHORS' CONCLUSIONS

This review update suggests that computerized advice for drug dosage has some benefits: it increases the serum concentrations for aminoglycoside antibiotics and improves the proportion of people for which the plasma drug is within the therapeutic range for aminoglycoside antibiotics.It leads to a physiological parameter more often within the desired range for oral anticoagulants and insulin. It decreases the time to achieve stabilization for oral anticoagulants. It tends to decrease unwanted effects for aminoglycoside antibiotics and anti-rejection drugs, and it significantly decreases thromboembolism events for anticoagulants. It tends to reduce the length of hospital stay compared with routine care while comparable or better cost-effectiveness ratios were achieved.However, there was no evidence that decision support had an effect on mortality or other clinical adverse events for insulin (hypoglycaemia), anaesthetic agents, anti-rejection drugs and antidepressants. In addition, there was no evidence to suggest that some decision support technical features (such as its integration into a computer physician order entry system) or aspects of organization of care (such as the setting) could optimize the effect of computerized advice.Taking into account the high risk of bias of, and high heterogeneity between, studies, these results must be interpreted with caution.

Towards optimal treatment with growth hormone in short children and adolescents: evidence and theses

Treatment with growth hormone (GH) has become standard practice for replacement in GH-deficient children or pharmacotherapy in a variety of disorders with short stature. However, even today, the reported adult heights achieved often remain below the normal range. In addition, the treatment is expensive and may be associated with long-term risks. Thus, a discussion of the factors relevant for achieving an optimal individual outcome in terms of growth, costs, and risks is required. In the present review, the heterogenous approaches of treatment with GH are discussed, considering the parameters available for an evaluation of the short- and long-term outcomes at different stages of treatment. This discourse introduces the potential of the newly emerging prediction algorithms in comparison to other more conventional approaches for the planning and evaluation of the response to GH. In rare disorders such as those with short stature, treatment decisions cannot easily be deduced from personal experience. An interactive approach utilizing the derived experience from large cohorts for the evaluation of the individual patient and the required decision-making may facilitate the use of GH. Such an approach should also lead to avoiding unnecessary long-term treatment in unresponsive individuals.

Growth hormone therapy and craniofacial bones: a comprehensive review

Growth hormone (GH) has significant effects on linear bone growth, bone mass and bone metabolism. The primary role of GH supplementation in children with GH deficiency, those born small for gestational age or with other types of disorders in somatic development is to increase linear growth. However, GH therapy seems to elicit varying responses in the craniofacial region. Whereas the effects of GH administration on somatic development are well documented, comparatively little is known of its effects on the craniofacial region. The purpose of this review was to search the literature and compile results from both animal and human studies related to the impact of GH on craniofacial growth.

The benefits of growth hormone therapy in patients with Turner syndrome, Noonan syndrome and children born small for gestational age

This review will summarize the effects of growth hormone (GH) on height, body composition, bone and psychosocial parameters in children with Turner syndrome or Noonan syndrome and those born small for gestational age. The safety of GH treatment in children with these diagnoses is also reported. Despite the reported efficacy and safety of GH in these indications, however, not all children achieve their target height potential, due in some part to poor adherence to GH therapy regimens; indeed up to 50% of children are less than fully compliant with treatment. With this in mind the present and future administration of GH therapy is discussed with respect to advances being made in the presentation of GH for injection and advances in GH injection devices. It is hoped that such progress, aimed at making the administration of GH easier and less painful for the patient will improve treatment adherence and outcome benefits.

[Clinical predictors of growth response in the first year of treatment with a fixed dose of growth hormone in children born small for gestational age]

OBJECTIVE

To identify clinical predictors associated with catch-up growth in the first year of treatment with somatropin (rhGH) in a group of children born small for gestational age (SGA).

SUBJECTS AND METHODS

Thirty nine children who have been on rhGH therapy for at least one year (0.33 mg/kg/week) were evaluated. The clinical parameters analyzed were chronological age (CA), bone age (BA), target height and standard deviations scores (SDS) of birth weight and length, height, weight and growth rate.

RESULTS

rhGH therapy was associated with a first year height increment of 0.67 SDS (p < 0.01). BA and birth weight SDS were predictive of growth response, with statistical difference in height SDS variation between prepubertal and pubertal subgroups (p = 0.016).

CONCLUSION

These data show a significant growth response with a fixed rhGH dose, those children who started rhGH in prepubertal ages presented the best outcomes.