Oxandrolone for growth hormone-treated girls aged up to 18 years with Turner syndrome

BACKGROUND

The final adult height of untreated girls aged up to 18 years with Turner syndrome (TS) is approximately 20 cm shorter compared with healthy females. Treatment with growth hormone (GH) increases the adult height of people with TS. The effects of adding the androgen, oxandrolone, in addition to GH are unclear. Therefore, we conducted this systematic review to investigate the benefits and harms of oxandrolone as an adjuvant therapy for people with TS treated with GH.

OBJECTIVES

To assess the effects of oxandrolone on growth hormone-treated girls aged up to 18 years with Turner syndrome.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, the ICTRP Search Portal and ClinicalTrials.gov. The date of the last search was October 2018. We applied no language restrictions.

SELECTION CRITERIA

We included randomised controlled clinical trials (RCTs) that enrolled girls aged up to 18 years with TS who were treated with GH and oxandrolone compared with GH only treatment.

DATA COLLECTION AND ANALYSIS

Three review authors independently screened titles and abstracts for relevance, selected trials, extracted data and assessed risk of bias. We resolved disagreements by consensus, or by consultation with a fourth review author. We assessed trials for overall certainty of the evidence using the GRADE instrument.

MAIN RESULTS

We included six trials with 498 participants with TS, 267 participants were randomised to oxandrolone plus GH treatment and 231 participants were randomised to GH only treatment. The individual trial sample size ranged between 22 and 133 participants. The included trials were conducted in 65 different paediatric endocrinology healthcare facilities including clinics, centres, hospitals and academia in the USA and Europe. The duration of interventions ranged between 3 and 7.6 years. The mean age of participants at start of therapy ranged from 9 to 12 years. Overall, we judged only one trial at low risk of bias in all domains and another trial at high risk of bias in most domains. We downgraded the level of evidence mainly because of imprecision (low number of trials, low number of participants or both). Comparing oxandrolone plus GH with GH only for final adult height showed a mean difference (MD) of 2.7 cm in favour of oxandrolone plus GH treatment (95% confidence interval (CI) 1.3 to 4.1; P < 0.001; 5 trials, 270 participants; moderate-quality evidence). The 95% prediction interval ranged between 0.3 cm and 5.1 cm. For adverse events, we based our main analysis on reliable date from two trials with overall low risk of bias. There was no evidence of a difference between oxandrolone plus GH and GH for adverse events (RR 1.81, 95% CI 0.83 to 3.96; P = 0.14; 2 trials, 170 participants; low-quality evidence). Six out of 86 (18.6%) participants receiving oxandrolone plus GH compared with 8/84 (9.5%) participants receiving GH only reported adverse events, mainly signs of virilisation (e.g. deepening of the voice). One trial each investigated the effects of treatments on speech (voice frequency; 88 participants), cognition (51 participants) and psychological status (106 participants). The overall results for these comparisons were inconclusive (very low-quality evidence). No trial reported on health-related quality of life or all-cause mortality.

AUTHORS' CONCLUSIONS

Addition of oxandrolone to the GH therapy led to a modest increase in the final adult height of girls aged up to 18 years with TS. Adverse effects identified included virilising effects such as deepening of the voice, but reporting was inadequate in some trials.