Inhaled corticosteroids in children with persistent asthma: effects on growth

Background

Treatment guidelines for asthma recommend inhaled corticosteroids (ICS) as first-line therapy for children with persistent asthma. Although ICS treatment is generally considered safe in children, the potential systemic adverse effects related to regular use of these drugs have been and continue to be a matter of concern, especially the effects on linear growth.

Objectives

To assess the impact of ICS on the linear growth of children with persistent asthma and to explore potential effect modifiers such as characteristics of available treatments (molecule, dose, length of exposure, inhalation device) and of treated children (age, disease severity, compliance with treatment).

Search methods

We searched the Cochrane Airways Group Specialised Register of trials (CAGR), which is derived from systematic searches of bibliographic databases including CENTRAL, MEDLINE, EMBASE, CINAHL, AMED and PsycINFO; we handsearched respiratory journals and meeting abstracts. We also conducted a search of ClinicalTrials.gov and manufacturers' clinical trial databases to look for potential relevant unpublished studies. The literature search was conducted in January 2014.

Selection criteria

Parallel-group randomised controlled trials comparing daily use of ICS, delivered by any type of inhalation device for at least three months, versus placebo or non-steroidal drugs in children up to 18 years of age with persistent asthma.

Data collection and analysis

Two review authors independently performed study selection, data extraction and assessment of risk of bias in included studies. We conducted meta-analyses using the Cochrane statistical package RevMan 5.2 and Stata version 11.0. We used the random-effects model for meta-analyses. We used mean differences (MDs) and 95% CIs as the metrics for treatment effects. A negative value for MD indicates that ICS have suppressive effects on linear growth compared with controls. We performed a priori planned subgroup analyses to explore potential effect modifiers, such as ICS molecule, daily dose, inhalation device and age of the treated child.

Main results

We included 25 trials involving 8471 (5128 ICS-treated and 3343 control) children with mild to moderate persistent asthma. Six molecules (beclomethasone dipropionate, budesonide, ciclesonide, flunisolide, fluticasone propionate and mometasone furoate) given at low or medium daily doses were used during a period of three months to four to six years. Most trials were blinded and over half of the trials had drop out rates of over 20%.

Compared with placebo or non-steroidal drugs, ICS produced a statistically significant reduction in linear growth velocity (14 trials with 5717 participants, MD -0.48 cm/y, 95% CI -0.65 to -0.30, moderate quality evidence) and in the change from baseline in height (15 trials with 3275 participants; MD -0.61 cm/y, 95% CI -0.83 to -0.38, moderate quality evidence) during a one-year treatment period.

Subgroup analysis showed a statistically significant group difference between six molecules in the mean reduction of linear growth velocity during one-year treatment (Chi² = 26.1, degrees of freedom (df) = 5, P value < 0.0001). The group difference persisted even when analysis was restricted to the trials using doses equivalent to 200 μg/d hydrofluoroalkane (HFA)-beclomethasone. Subgroup analyses did not show a statistically significant impact of daily dose (low vs medium), inhalation device or participant age on the magnitude of ICS-induced suppression of linear growth velocity during a one-year treatment period. However, head-to-head comparisons are needed to assess the effects of different drug molecules, dose, inhalation device or patient age. No statistically significant difference in linear growth velocity was found between participants treated with ICS and controls during the second year of treatment (five trials with 3174 participants; MD -0.19 cm/y, 95% CI -0.48 to 0.11, P value 0.22). Of two trials that reported linear growth velocity in the third year of treatment, one trial involving 667 participants showed similar growth velocity between the budesonide and placebo groups (5.34 cm/y vs 5.34 cm/y), and another trial involving 1974 participants showed lower growth velocity in the budesonide group compared with the placebo group (MD -0.33 cm/y, 95% CI -0.52 to -0.14, P value 0.0005). Among four trials reporting data on linear growth after treatment cessation, three did not describe statistically significant catch-up growth in the ICS group two to four months after treatment cessation. One trial showed accelerated linear growth velocity in the fluticasone group at 12 months after treatment cessation, but there remained a statistically significant difference of 0.7 cm in height between the fluticasone and placebo groups at the end of the three-year trial.

One trial with follow-up into adulthood showed that participants of prepubertal age treated with budesonide 400 μg/d for a mean duration of 4.3 years had a mean reduction of 1.20 cm (95% CI -1.90 to -0.50) in adult height compared with those treated with placebo.

Authors' conclusions

Regular use of ICS at low or medium daily doses is associated with a mean reduction of 0.48 cm/y in linear growth velocity and a 0.61-cm change from baseline in height during a one-year treatment period in children with mild to moderate persistent asthma. The effect size of ICS on linear growth velocity appears to be associated more strongly with the ICS molecule than with the device or dose (low to medium dose range). ICS-induced growth suppression seems to be maximal during the first year of therapy and less pronounced in subsequent years of treatment. However, additional studies are needed to better characterise the molecule dependency of growth suppression, particularly with newer molecules (mometasone, ciclesonide), to specify the respective role of molecule, daily dose, inhalation device and patient age on the effect size of ICS, and to define the growth suppression effect of ICS treatment over a period of several years in children with persistent asthma.

PLAIN LANGUAGE SUMMARY

Do inhaled corticosteroids reduce growth in children with persistent asthma?

Review question: We reviewed the evidence on whether inhaled corticosteroids (ICS) could affect growth in children with persistent asthma, that is, a more severe asthma that requires regular use of medications for control of symptoms.

Background: Treatment guidelines for asthma recommend ICS as first-line therapy for children with persistent asthma. Although ICS treatment is generally considered safe in children, parents and physicians always remain concerned about the potential negative effect of ICS on growth.

Search date: We searched trials published until January 2014.

Study characteristics: We included in this review trials comparing daily use of corticosteroids, delivered by any type of inhalation device for at least three months, versus placebo or non-steroidal drugs in children up to 18 years of age with persistent asthma.

Key results: Twenty-five trials involving 8471 children with mild to moderate persistent asthma (5128 treated with ICS and 3343 treated with placebo or non-steroidal drugs) were included in this review. Eighty percent of these trials were conducted in more than two different centres and were called multi-centre studies; five were international multi-centre studies conducted in high-income and low-income countries across Africa, Asia-Pacifica, Europe and the Americas. Sixty-eight percent were financially supported by pharmaceutical companies.

Meta-analysis (a statistical technique that combines the results of several studies and provides a high level of evidence) suggests that children treated daily with ICS may grow approximately half a centimeter per year less than those not treated with these medications during the first year of treatment. The magnitude of ICS-related growth reduction may depend on the type of drug. Growth reduction seems to be maximal during the first year of therapy and less pronounced in subsequent years of treatment. Evidence provided by this review allows us to conclude that daily use of ICS can cause a small reduction in height in children up to 18 years of age with persistent asthma; this effect seems minor compared with the known benefit of these medications for asthma control.

Quality of evidence: Eleven of 25 trials did not report how they guaranteed that participants had an equal chance of receiving ICS or placebo or non-steroidal drugs. All but six trials did not report how researchers were kept unaware of the treatment assignment list. However, this methodological limitation may not significantly affect the quality of evidence because the results remained almost unchanged when we excluded these trials from the analysis.