John: Hello, I'm John Hilton, editor of the Cochrane Editorial unit. Corticosteroids are a widely used treatment for asthma and a recent addition to the collection of Cochrane Reviews on this condition examines the research that compared different ways of using them. Rebecca Normansell and Kayleigh Kew from the Population Health Research Institute at St George's in the University of London in the UK describe the findings of this May 2016 review in this Evidence Pod, starting with Rebecca.

Rebecca / Kayleigh: Corticosteroids, which are often just known as steroids, are commonly prescribed when people with asthma have an asthma attack, a flare-up of their symptoms. The drugs can be given as an injection but are usually given orally, in tablet form, and that’s what we looked at in this review. The most commonly prescribed oral steroid is prednisolone, which is called prednisone in some parts of the world; but the tablets can be taken for varying lengths of time and at different doses.
Although we know that steroids are very effective for treating asthma attacks, we also know that many people experience unpleasant side effects, such as nausea, insomnia and changes in their mood. When taken frequently or for a long time they can also cause other more permanent changes such as thinning of the bones and skin and increased weight, and in children they may reduce growth.
We wanted to find out whether there was evidence about the dose or length of a course of oral steroids for asthma attacks that would ensure that people with asthma get better without experiencing too many side effects.
We looked for trials that had compared one dose or length of oral steroid course to another dose or duration in people who were having an asthma attack.
After our most recent search in April 2016, we’d found 18 studies that included approximately 2500 people with asthma, both children and adults.
However, some of the studies were quite old and did not use doses of steroids that are commonly used today. The studies ranged in size from the smallest, with just 15 people, to the largest, with 638; and the participants were followed for between seven days and six months. A variety of different steroid doses and course lengths had been compared, including higher versus lower doses of prednisolone, longer versus shorter courses of prednisolone or dexamethasone, and prednisolone versus dexamethasone. Dexamethasone is a different steroid that can usually be given for a shorter time because it stays in the body for longer.
The studies were mostly carried out in North America and the UK, although some had been done in Australia, Japan, Indonesia, India and Ireland. We judged most of the studies to be reasonably well conducted in terms of the methods they used, but in some studies it was not clearly explained how the trial organisers had decided which people would receive which dose of steroids, and in some studies, both participants and trial organisers knew which dose they were getting. Both these factors could have had an impact on the results.
We were not able to combine many of the results from the individual studies because of the differences between them. This has limited our confidence in the findings and two of the outcomes we were most interested in – being admitted to hospital and experiencing a serious side effect – happened so rarely that we could not be sure whether one dose or length of course was better than another, or whether they were the same. Researchers in the included studies also measured asthma symptoms in different ways, which added to our difficulties in combining results.
With these problems in mind, we have to conclude that the current evidence is not strong enough to reveal whether shorter or lower-dose courses of steroids work less well for asthma attacks than longer or higher-dose courses, or if longer or higher dose courses cause more side effects. Therefore, any changes to the way in which asthma attacks are currently managed with oral steroids would need to be supported by larger studies than have been conducted so far.

John: Thanks Kayleigh. If you’d like to read about the current evidence, or watch for updates of this review should those larger studies become available, visit Cochrane Library dot com and search ‘corticosteroid regimens and asthma’.

Hello, I'm John Hilton, editor of the Cochrane Editorial unit.