Thursday July 17 2014
Inhalers are used to prevent and relieve symptoms
“Children who use inhalable steroids for asthma grow slower than their peers in the first year of taking the medication,” The Guardian reports. While this is an accurate report of the science, the effect found by researchers was small. On average, a reduction of around half a centimetre per year was seen, compared to children taking a placebo or other asthma medication.
The researchers were studying the effects of inhaled corticosteroids. These are known as “preventers” – the brown inhalers that deliver a dose of steroids to the airways reducing inflammation, to prevent symptoms.
After pooling the results of 25 trials, they found a small but significant link between the use of preventer inhalers and restricted childhood growth, which was estimated to be an average reduction of 0.48cm (or 0.19in).
The authors recommend that these drugs should be prescribed at the “lowest effective dose” and that the growth rate of children treated with inhaled corticosteroids should be monitored, as they will affect each child differently.
However, as the authors point out, the small effect on growth is a minor risk compared to the proven benefits of these drugs in controlling asthma, and ensuring children’s lungs grow to their full capacity.
Untreated childhood asthma is much more likely to have a harmful effect on a child’s development than a small reduction in growth.
It is therefore important that parents ensure their children use their inhalers as advised by their doctor.
Where did the story come from?
The study was carried out by researchers from the Federal University of Rio Grande, Brazil, and the University of Montreal, in Canada. There was no external funding.
The study was published by the Cochrane Collaboration – an independent research body looking at the effects of healthcare treatments.
As with all Cochrane Collaboration publications, the research was peer-reviewed. It is available on an open-access basis, so is free to read online.
Not surprisingly, it was widely covered by the media, with most news sources responsibly including warnings from independent researchers and doctors that uncontrolled asthma can be dangerous.
The Independent rightly report that the effect of inhalers on growth was “a small price to pay” to protect against potentially lethal asthma attacks.
What kind of research was this?
This was a systematic review and meta-analysis of the evidence on whether drugs called “inhaled corticosteroids” (steroids) can affect the growth of children with persistent asthma.
Children with persistent asthma often require regular use of this medication to prevent symptoms, such as wheezing, from reoccurring.
The researchers also investigated whether factors such as the type of medication, dose, the length of time taken and the type of inhalation device used had any role in modifying the potential effect on growth.
Systematic reviews of randomised controlled trials (RCTs) are the best way of assessing the benefits and risks of healthcare interventions. A meta-analysis is a statistical technique that combines the results of several studies.
Inhaled steroids are recommended as a first line treatment for children with persistent, mild to moderate asthma. These drugs are the most effective method of treating asthma and are generally considered safe. However, parents and doctors remain concerned about the potential negative effect on growth, which has been suggested by previous research. Their aim was to evaluate the adverse effects on growth in children of all the currently available inhaled steroids.
What did the research involve?
The researchers searched for trials that addressed this question on a Cochrane specialist register of trials, which is derived from systematic searches of various electronic databases. They also hand-searched respiratory journals and meeting abstracts. All databases were searched from their inception to January 2014.
They looked for RCTs involving children up to 18 years of age, with persistent asthma, who had used ICS daily for at least three months, and who had been compared with children using a placebo or non-steroid drug.
They then assessed children’s rate of linear growth by measuring height at a number of points in the study.
Differences between growth rate and predicted normal growth rates for children of the same age, sex and ethnicity, and changes from baseline in height over time were also considered.
The authors of the Cochrane research assessed the abstracts of all studies identified as potentially relevant, and where they met the study criteria, extracted the relevant data. They also independently assessed the quality of the trials and the risk of bias. The quality of RCTs may vary, depending on how well they are designed, conducted and reported.
They used validated statistical methods to analyse the results.
What were the basic results?
The review included 25 trials, involving 8,471 children with mild to moderate persistent asthma.
The trials tested six medications (beclomethasone dipropionate, budesonide, ciclesonide, flunisolide, fluticasone propionate and mometasone fumarate), given at low or medium daily doses during a period of three months to four to six years.
They found that:
- compared with placebo or non-steroidal drugs, inhaled steroids produced a statistically significant reduction in a person’s growth rate (mean difference -0.48cm/y, 95% Confidence Interval [CI] 0.65 to 0.30, moderate quality evidence)
- this represented an overall decrease from the expected baseline in height (mean difference 0.61cm/y, 95% CI 0.83 to 0.38, moderate quality evidence) during a one-year treatment period (that is, on average, children were 0.61cm shorter than would have been expected)
- the scale of growth reduction in children treated with inhaled steroids varied according to the type of drugs used, with the smallest reduction found for ciclesonide, but this was based on just one study of 202 children
- results for further years varied between trials, but overall, growth reduction was less pronounced in subsequent years of treatment
- one trial that followed children into adulthood showed that prepubertal children treated with the drug budesonide for an average of 4.3 years had an average reduction of 1.20cm (95% CI 1.90 to 0.50) in adult height, compared to those treated with a placebo
A second Cochrane review of 22 trials found that the effects on growth were minimised when lower doses of inhaled steroids were used.
How did the researchers interpret the results?
The researchers say the evidence suggests that children treated daily with inhaled steroids may grow about half a centimetre less during their first year of treatment, with the effect on growth less pronounced in subsequent years.
Further research is now needed, they say, comparing different inhaled doses of corticosteroids, especially in children with more severe asthma, who require higher doses.
They conclude that while the benefits of inhaled steroids outweigh the potential risk of a relatively small suppression in growth rates, these drugs should be prescribed at the “lowest effective dose”, and the growth rate of children treated with inhaled steroids drugs should be monitored, since individual susceptibility may vary.
This systematic review has found that inhaled corticosteroid drugs suppress growth in children with persistent asthma who take them regularly, during the first year of treatment.
This was high quality, well-conducted research, and its conclusions are likely to be reliable.
While the results are likely to worry parents, uncontrolled asthma can restrict a child’s activities and lower their quality of life. In severe cases, it can lead to life-threatening asthma attacks.
Even low-grade, persistent symptoms can lead to fatigue, underperformance or absence from school as well as psychological problems, including stress, anxiety and depression.
It's important that children continue to take their asthma medication as prescribed. Parents should discuss any concerns about their child’s prescription with their doctor.
Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. Join the Healthy Evidence forum.