Turner syndrome (TS) is one of the common chromosomal abnormalities in girls. TS was initially described by Otto Ullrich in 1930 and later in 1938 by Henry Turner who described this syndrome in seven females with short stature, sexual infantilism, webbed neck and cubitus valgus (Turner 1938; Ullrich 1930). The incidence of TS is 1 in 2000 to 2500 female live births (Nielsen 1991; Pinsker 2012; Stochholm 2006). Most of the pregnancies with TS result in abortion. Gravholt et al studied the prevalence of TS karyotypes among prenatally tested fetuses and TS among liveborn infants in Denmark from 1970 to 1993 (Gravholt 1996). Their data showed that among female fetuses tested by amniocentesis, the prevalence of TS karyotypes was 176/100,000 while the prevalence was 392/100,000 among female fetuses tested by chorion villus sampling. These data proved that the prevalence of TS is not only influenced by testing during pregnancy or after birth but also depends on the method of prenatal testing (Gravholt 1996).
Description of the condition
TS is characterised by complete or partial loss of the second X chromosome (Nielsen 1991). Complete loss of one X chromosome (45 X) results in classical features of the disease while mosaics present with varying and generally lesser degrees of manifestation. Variable aberrations of the second X chromosome such as deletion, ring chromosome, and isochromosome cause phenotypic features of TS in 46 XX patients. The most frequent chromosomal abnormality in TS is 45 X (Nielsen 1991; Pinsker 2012; Stochholm 2006). The Danish TS registry showed that the 45 X karyotype was found in half of patients, followed by mosaics (Gravholt 1996).
TS is a multisystem disorder with the cardiovascular, skeletal, endocrine and reproductive systems mostly affected (Stochholm 2006). Lymphoedema of the hand and foot is an early sign of TS. Other dysmorphic features include widely spaced nipples, cubitus valgus, short webbed neck, low posterior hairline and narrow hyperconvex nails (Baxter 2007; Nielsen 1991; Pinsker 2012; Stochholm 2006). Congenital heart diseases are more frequent in individuals with TS compared to the general population (Stochholm 2006). The Italian study group for TS reported on cardiac anomalies in 594 patients with the disease (Mazzanti 1998). The prevalence of cardiac malformations in this study was 23%, with bicuspid aortic valve (12.5%), aortic coarctation (6.9%) and aortic valve disease (3.2%). Growth failure in childhood leading to short final adult height is the cardinal sign in girls with TS (Pinsker 2012; Stochholm 2006). While their birth weight is slightly impaired in utero, girls with TS may present early in childhood with failure to thrive (Davenport 1999). The height of patients with TS, when plotted on growth curves specific for this disorder, shows that growth velocity declinesbelow the reference growth curve for females often as early as two to four years of age (Saenger 1999). The adult height (defined as the height at which the epiphyses are closed or height velocity is less than 1 cm/year) of Turner patients is approximately 20 cm below that of the average female population. Naeraa and Nielsen studied growth parameters in 78 patients with TS (Naeraa 1990; Nielsen 1991). Analysis of the growth pattern showed that though no pubertal growth spurt was present, the steady decrease of height velocity (defined as increment in height per year in centimetres) was interrupted at the age of nine years. Height velocity was then constant until 12 years of age, thereafter it slowly decreased. The mean final height of this cohort was 146.8 cm (SD 5.8 cm, N = 76) compared to 166.8 cm in the general female population (Naeraa 1990). Therefore, short final adult height in TS is explained by poor childhood growth in addition to the lack of a pubertal growth spurt.
Hypergonadotrophic hypogonadism resulting from ovarian failure is a cardinal feature of TS. Primary infertility and lack of pubertal signs are seen in the vast majority of girls with TS (Bondy 2007). Spontaneous puberty and rarely pregnancy are reported in a minority of patients with TS, most of them carrying mosaic karyotype (Tracy 2011). Assisted reproduction remains an option to achieve pregnancy for women with primary ovarian failure including those with TS (Tracy 2011).
Characteristic neurocognitive features of TS include normal verbal function and impaired visual-spatial and perceptual abilities, attention, working memory, and spatially dependent executive function (Ross 2006). However, global developmental delay is uncommon in TS (Nielsen 1991; Pinsker 2012; Stochholm 2006). Short stature, delayed puberty and the presence of dysmorphic features contribute to the social and emotional impairment observed in TS (Ross 2006). Failure to treat growth and puberty stigmata may lead to further psychological and psychiatric problems (Bondy 2007; Carel 2006).
Description of the intervention
Growth hormone (GH) is a peptide hormone secreted by the anterior pituitary gland. GH promotes linear growth by stimulating production of insulin-like growth factor 1 that acts at the growth plate by enhancing differentiation of prechondrocytes and the expansion of osteoblasts (Reh CS 2010).
GH is currently used as a once-daily subcutaneous injection, typically given late in the evening to mimic the physiological secretory pattern of endogenous GH (Reh CS 2010). There is a wide range of recommended dosing of GH internationally for the treatment of growth-hormone deficiency. The dose of GH ranges between 0.5 to 0.7 IU/kg/week (0.17 to 0.23 mg/kg/week) in most countries (Tanaka 1999).
GH is generally safe with adverse events such as benign intracranial hypertension, slipped femoral epiphysis, worsening of scoliosis and impaired glucose homeostasis infrequently observed (Bell 2010; Wilton 1999).
Recombinant human GH was approved by the US Food and Drug Administration (FDA) for use in children with GH deficiency in 1985 and for TS in 1996. In the last three decades, multiple studies have confirmed the effectiveness and safety of GH therapy (Bell 2010; Reh CS 2010; Tanaka 1999; Takeda 2010).
Currently GH therapy is recommended for all children and adolescents with TS as the evidence supports this intervention (Baxter 2007; Canadian Growth Hormone Advisory Committee 2005; Takeda 2010). Standard management of TS entails starting GH in childhood to maximise height gain and to improve the final adult height (Bondy 2007; Davenport 2007; Ranke 2007; Stephure 2005). Furthermore, treatment with GH positively affects body composition by increasing muscle mass and decreasing fat mass (Gravholt 2002). A Cochrane systematic review investigated the effects of GH in children and adolescents with TS (Baxter 2007). Four randomised controlled trials (RCTs) that included 365 participants after one year of treatment were included. This systematic review concluded that GH increases short-term growth in girls with TS by approximately 3 cm in the first year of treatment and 2 cm in the second year. In one trial treatment increased final height by approximately 6 cm over the height in an untreated control group. The optimal age for initiation of GH therapy for young children has not been established. Davenport et al showed that early GH treatment can correct growth failure and normalize height in infants and toddlers with TS (Fechner 2007).
Carel et al carried out a population-based cohort study of health-related quality of life determinants in 568 young women with TS using the 'Medical Outcome Study Short Form 36' (SF-36) score and the 'General Health Questionnaire' 12 score (Carel 2005; Carel 2006). This study concluded that health-related quality of life is normal and unaffected by height in young adults with TS treated with GH. Similar results were reported by Taback et al who conducted a follow-up study on the health-related quality of life of young adults from a long-term controlled trial of GH treatment in patients with TS (Taback 2011). This study found no benefit or adverse effects on health-related quality of life either from receiving or not receiving GH injections in a long-term RCT.
The majority of patients with TS have delayed puberty leading to the lack of a pubertal growth spurt, which compromises the final adult height. Therefore oestrogen is commonly started on top of GH in order to induce puberty and maximize final adult height (Bondy 2007; Van Pareren 2003).
Oxandrolone (Ox) is an anabolic steroid (a synthetic derivative of testosterone). It is a weak androgen (Menke 2011) and is available in 2.5 mg and 10 mg tablets. The dose for children is weight based (0.1 mg/kg), however have been wide variations in the Ox dose (mostly 0.03 to 0.06 mg/kg/d) used in different studies investigating growth promotion in TS (Bareille 1997; Gault 2011; Job 1991; Joss 1984; Menke 2010; Nilsson 1996; Rosenfeld 1992; Stahnke 2002; Zeger 2011). Recently a stable and validated liquid formulation of oxandrolone has been developed. This formulation uses commercially available oxandrolone tablets which are crushed and dispersed in syrup (Garg 2011). Historically, Ox was initially approved in 1964 for treatment of wasting associated with conditions such as chronic infection, severe trauma, and after extensive surgery (Mann 1999). In the last two decades, Ox was used as an adjuvant therapy to promote healing in severe burning (Hart 2001; Sheffield-Moore 1999).
In order to improve growth, Ox is usually started a few years before the appropriate age for induction of puberty in girls with TS. Both GH and Ox are discontinued when the adult final height has been achieved (Bondy 2007; Stochholm 2006).
Adverse effects of the intervention
Adverse effects associated with Ox include signs of virilization such as clitoral enlargement, acne, lowering of the voice, and more rapid skeletal maturation (Carolyn 2007).
How the intervention might work
Although Ox is a known anabolic steroid, the exact mechanism by which Ox improves growth is unknown. It may act directly on the growth plate (Haeusler 1996; Sheffield-Moore 1999; Wilson 1998). The advantage of Ox over other growth promoting androgens is that it may improve the final adult height and at the same time does not promote bone maturation that leads to early fusion of the epiphysis (Bareille 1997; Gault 2011; Haeusler 1996; Job 1991; Joss 1984; Menke 2010; Nilsson 1996; Rosenfeld 1992; Stahnke 2002; Wilson 1998; Zeger 2011).
Why it is important to do this review
The use of Ox as an adjuvant therapy to GH aiming to maximize the final adult height is unclear. There is currently no published systematic review investigating the role of Ox in the management of girls with TS. Therefore, we would like to conduct a systematic review to evaluate the effects and safety of Ox in patients with TS already treated with GH. This will help physicians and health policy developers to make evidence-based recommendations regarding the role of Ox in TS.
To assess the effects of oxandrolone on growth-hormone treated children and adolescents with Turner syndrome (TS).
Criteria for considering studies for this review
Types of studies
Randomised controlled clinical trials (RCTs).
Types of participants
Growth-hormone treated children and adolescents with TS.
As some patients with TS lack the clinical phenotype suggestive of the disease, all participants included in this review should have their diagnosis of TS confirmed by a chromosomal study. This includes complete (45 X) or partial loss of the second X chromosome (such as deletion, ring chromosome, and isochromosome). Mosaics will also be included in this review.
Types of interventions
Growth hormone (GH) treatment should have been given for at least one year. All other concurrent therapies should be comparable between the intervention and comparator groups.
- Oxandrolone and GH treatment.
- GH treatment only.
Types of outcome measures
- Improvement in final adult height or increase in height velocity in children who had not reached their final adult height
- Health-related quality of life
- Adverse effects (e.g. virilization effects on hair distribution, deepening of voice, clitromegaly)
- All-cause mortality
- Bone maturation
- Effects on cognition
- Effects on psychological status
- Effects on speech
- Socioeconomic costs
Timing of outcome measurement
Short-term outcome measurements include measurement of annual height velocity and observing adverse effects in the first year of intervention. Medium-term outcomes include attaining near adult height (defined as age at which the height velocity is 2 cm per year). Long-term outcome measurements include measuring final adult height when epiphyses are closed and assessing the effects of the intervention on health-related quality of life.
Definition of outcome measurement
- Bone maturation has to be assessed by X-ray of the left hand for bone age and closure of the epiphysis.
- Effects on cognition have to be measured by a validated instrument like the 'Wechsler Intelligence Scale for Children Third Edition' (Wechsler 1991).
- Effects on psychological status have to be measured by a validated instrument such as the 'Diagnostic and Statistical Manual of Mental Disorders' (DSM-4) (Conway 2012).
- Effects on speech have to be assessed by the speaking fundamental frequency (Andersson-Wallgren 2008).
- Height velocity is defined as increment in height per year in centimeters.
Summary of findings table
We will present a 'Summary of findings' table reporting the following outcomes listed according to priority.
- Final adult height.
- Adverse events.
- Health-related quality of life.
- Effects on speech.
- Effects on cognition.
- Effects on psychological status.
- All-cause mortality.
Search methods for identification of studies
A comprehensive search will be conducted using primarily electronic databases. The following words will be used: Turner's Syndrome AND oxandrolone using a combination of both MeSH terms (medical subheadings) and text words.
We will search the following sources from inception to the present.
- The Cochrane Library.
We will also search databases of ongoing trials including ClinicalTrials.gov (http://clinicaltrials.gov/), metaRegister of Controlled Trials (http://www.controlled-trials.com/mrct/), the EU Clinical Trials register (https://www.clinicaltrialsregister.eu/) and the World Health Organization (WHO) International Clinical Trials Registry Platform Search Portal (http://apps.who.int/trialsearch/).
For detailed search strategies please see Appendix 1. We will continuously apply PubMed's 'My NCBI' (National Center for Biotechnology Information) e-mail alert service for identification of newly published studies using a basic search strategy (see Appendix 1). Four weeks before we submit the final review draft to the Cochrane Metabolic and Endocrine Disorders Group (CMED) for editorial approval we will perform a complete updated search on all specified databases. Should we detect new studies for inclusion we will evaluate these and incorporate findings in our review before submission of the final review draft.
If we detect additional relevant key words during any of the electronic or other searches, we will modify the electronic search strategies to incorporate these terms and document the changes. We will place no restrictions on the language of publication when searching the electronic databases or reviewing reference lists in identified studies.
We will send results of electronic searches to the CMED for databases which are not available at the editorial office.
Searching other resources
We will try to identify other potentially eligible trials or ancillary publications by searching the reference lists of retrieved included trials, (systematic) reviews, meta-analyses, and health technology assessment reports.
Oxadrolone manufacturers' websites, FDA and European Medicines Agency (EMA) websites will be searched.
Data collection and analysis
Selection of studies
To determine the studies to be assessed further, three review authors (SM, YA, KA) will independently scan the abstract, title, or both sections of every record retrieved. We will investigate all potentially relevant articles as full texts. Where differences in opinion exist, they will be resolved by a third party (editorial office). If resolving the disagreement is not possible, the article will be added to those 'awaiting assessment' and we will contact the study authors for clarification. We will attach an adapted PRISMA (preferred reporting items for systematic reviews and meta-analyses) flow-chart of study selection (Figure 1) (Liberati 2009).
|Figure 1. Study flow diagram.|
Data extraction and management
For studies that fulfil the inclusion criteria, three review authors (SM, YA, KA) will independently abstract relevant population and intervention characteristics using a standard data extraction template (for details see Table 1; Appendix 2; Appendix 3; Appendix 4; Appendix 5; Appendix 6; Appendix 7; Appendix 8; Appendix 9; Appendix 10; Appendix 11) with any disagreements to be resolved by discussion or, if required, by a third party (editorial office).
We will provide information, including trial identifier, about potentially-relevant ongoing studies in the table 'Characteristics of ongoing studies' and in the appendix 'Matrix of study endpoints (trial documents)'. We will try to find the protocol of each included study, either in databases of ongoing trials, or in publications of study designs, or both, and specify the data in the appendix 'Matrix of study endpoints (trial documents)'.
We will send an e-mail to all study authors of included studies to enquire whether they are willing to answer questions regarding their trials.The results of this survey will be published in Appendix 12. Thereafter, we will seek relevant missing information on the trial from the primary author(s) of the article, if required.
Dealing with duplicate publications and companion papers
In the event of duplicate publications, companion papers, or multiple reports of a primary study, we will maximize the yield of information by collating all available data. In case of doubt, the publication reporting the longest follow-up associated with our primary or secondary outcomes will obtain priority.
Assessment of risk of bias in included studies
Three review authors (SM, YA, KA) will assess each trial independently. We will resolve possible disagreements by consensus, or in consultation with a third party. In cases of disagreement, the editorial office will be consulted and a judgement will be made based on consensus.
- Random sequence generation (selection bias).
- Allocation concealment (selection bias).
- Blinding (performance bias and detection bias), separated for blinding of participants and personnel and blinding of outcome assessment.
- Incomplete outcome data (attrition bias).
- Selective reporting (reporting bias).
- Other bias.
We will assess outcome reporting bias by integrating the results of 'Examination of outcome reporting bias' (Appendix 7), 'Matrix of study endpoints (trial documents)' (Appendix 6) and section 'Outcomes (outcomes reported in abstract of publication)' of the 'Characteristics of included studies' section (Kirkham 2010). This analysis will form the basis for the judgement of selective reporting (reporting bias).
We will judge risk of bias criteria as 'low risk', 'high risk' or 'unclear risk' and evaluate individual bias items as described in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011). We will attach a 'risk of bias' graph and 'Risk of bias summary' figure.
We will assess the impact of individual bias domains on study results at the endpoint and study levels.
For blinding of participants and personnel (performance bias), detection bias (blinding of outcome assessors), and attrition bias (incomplete outcome data) we intend to evaluate risk of bias separately for subjective and objective outcomes (Hróbjartsson 2013). We will consider the implications of missing outcome data from individual participants.
We define the following outcomes as subjective outcomes.
- Health-related quality of life.
- Effects on speech.
- Effects on cognition.
- Effect on psychological status.
- Adverse events.
We define the following outcomes as objective outcomes.
- Increment in height velocity and final adult height.
- Bone maturation.
- All-cause mortality.
- Socioeconomic costs.
Measures of treatment effect
We will express dichotomous data as odds ratios (ORs) or risk ratios (RRs) with 95% confidence intervals (CIs). We will express continuous data as differences in means (MD) with 95% CI.
Unit of analysis issues
We will take into account the level at which randomisation occurred, such as cluster-randomised trials and multiple observations for the same outcome.
Dealing with missing data
We will obtain relevant missing data from authors, if feasible, and carefully perform evaluation of important numerical data such as screened, randomised patients as well as intention-to-treat (ITT), as-treated and per protocol (PP) populations. We will investigate attrition rates, for example dropouts, losses to follow-up, and withdrawals and critically appraise issues of missing data and imputation methods (for example last observation carried forward (LOCF)).
Assessment of heterogeneity
In the event of substantial clinical, methodological or statistical heterogeneity, we will not report study results as the pooled effect estimate in a meta-analysis. We will identify heterogeneity by visual inspection of the forest plots and by using a standard Chi
When we find heterogeneity, we will attempt to determine potential reasons for it by examining individual study and subgroup characteristics.
We expect the following characteristics to introduce clinical heterogeneity:
- age of participants and age at which oxandrolone treatment was started;
- dose of oxandrolone;
- duration of oxandrolone therapy.
Assessment of reporting biases
If we include 10 studies or more for a given outcome, we will use funnel plots to assess small study effects. Due to several possible explanations for funnel plot asymmetry we will interpret results carefully (Sterne 2011).
Unless there is good evidence for homogeneous effects across studies we will primarily summarise low risk of bias data by means of a random-effects model (Wood 2008). We will interpret random-effects meta-analyses with due consideration of the whole distribution of effects, ideally by presenting a prediction interval (Higgins 2009). A prediction interval specifies a predicted range for the true treatment effect in an individual study (Riley 2011). In addition, we will perform statistical analyses according to the statistical guidelines referenced in the latest version of the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011).
Subgroup analysis and investigation of heterogeneity
We will carry out the following subgroup analyses and plan to investigate interaction.
- Participants who reached their final adult height at the end of the study versus those who did not reach their final height.
- Participants who received intervention or comparator for three years versus less than three years.
- Participants who received low-dose oxandrolone (0.03 mg/kg/d) versus those who received high-dose oxandrolone (0.06 mg/kg/d).
We will perform sensitivity analyses in order to explore the influence of the following factors on effect sizes.
- Restricting the analysis to published studies.
- Restricting the analysis by taking into account risk of bias, as specified above.
- Restricting the analysis to very long or large studies to establish how much they dominate the results.
- Restricting the analysis to studies using the following filters: diagnostic criteria, language of publication, source of funding (industry versus other), country.
We will also test the robustness of the results by repeating the analysis using different measures of effect size (RR, OR etc.) and different statistical models (fixed-effect and random-effects models).
The authors (SM, YA, KA) would like to acknowledge the following physicians for their support during the planning and development of this systematic review:
Dr Lubna Al-Ansary, Holder of Shaikh Bahmdan's Chair of Evidence Based Medicine and Translation of Knowledge, King Saud University;
Dr Abdulrahman MH Al Nemri, Chief of Pediatrics Department, College of Medicine, King Saud University;
Prof Nasir AM Al-Jurayyan, Head of Pediatric Endocrinology Unit, King Saud University;
Dr Amir Babiker, Consultant Pediatric Endocrinologist, King Saud University.
Appendix 1. Search strategies
Appendix 2. Description of interventions
Appendix 3. Baseline characteristics (I)
Appendix 4. Baseline characteristics (II)
Appendix 5. Matrix of study endpoints (publications)
Appendix 6. Matrix of study endpoints (trial documents)
Appendix 7. Examination of outcome reporting bias
Appendix 8. Definition of endpoint measurement
Appendix 9. Adverse events (I)
Appendix 10. Adverse events (II)
Appendix 11. Adverse events (III)
Appendix 12. Survey of authors providing information on trials
Contributions of authors
Sarar Mohamed (SM): protocol draft, search strategy development, acquirement of trial copies, trial selection, data extraction, data analysis, data interpretation, review draft and review update.
Yaser Adi (YA): protocol draft, search strategy development, acquirement of trial copies, trial selection, data extraction, data analysis, data interpretation, review draft and review update.
Khalid AlFaleh (KA): protocol draft, search strategy development, acquirement of trial copies, trial selection, data extraction, data analysis, data interpretation, review draft and review update.
Declarations of interest
Sources of support
- College of Medicine Research Center, Deanship of Scientific Research, King Saud University, Saudi Arabia.Provide access to journals and references, computer, and secretarial assistance
- Metabolic and Endocrine Group, Cochrane, Germany.Editing and reviewing protocol and helping with search strategy