We reviewed the evidence about the effect of inhaled corticosteroids in people with cystic fibrosis.
Repeated chest infections in people with cystic fibrosis cause inflammation and damage to the lungs which, in the long term, is the most common reason for death in people with cystic fibrosis. Inhaled corticosteroids are often used to treat inflammation, but may cause some side effects. Some of these side effects are less serious, for example oral thrush, but others are more serious, such as reduced growth rate in childhood. This is an update of an earlier review.
The last search for evidence was on 15 August 2016.
In this updated review, 13 trials reported the use of inhaled corticosteroids in 506 people with cystic fibrosis aged between 6 and 55 years. Three trials were in children only, four in adults only and four were mixed ages; two trials did not describe the ages of the volunteers. The lung function and severity of disease of the volunteers varied across trials and only two trials gave information about their genetic mutations. All trials took place in Europe. In 10 of the trials, all volunteers were in the same group up to the end of the trial (either a treatment group or a group receiving no treatment or a placebo (treatment that appeared the same as the steroids, but did not have any active medicine in it)), but in three trials they swapped groups halfway through the trial. In most of the trials volunteers started taking steroids or placebo at the start of the trial, but one trial was a withdrawal trial, where all volunteers were already taking steroids and half of them carried on and the rest took a placebo, in effect stopping the treatment. The trials lasted between three weeks and two years.
The clinical trials have not been able to prove that inhaled corticosteroids reduce inflammation in the lungs of people with cystic fibrosis. One trial has shown that these drugs can slow down children's growth when used in high doses. Furthermore it has been shown that under close supervision of the cystic fibrosis team, it may be safe for people who have been taking inhaled corticosteroids for some time to stop doing so.
Quality of the evidence
A lack of information meant we were often not able to judge if the way the trials were designed or run could have affected our confidence in the results. Only two trials gave details of how they made sure volunteers had equal chances of being in the treatment or placebo groups and only five supplied information on how they made sure the people recruiting volunteers didn't know which groups they would be going into. In most cases, we didn't think that once the trials started the volunteers or their doctors knew whether they were getting steroids or placebo. However, we did have some concerns that five of the trials had not been published in journals, that would send the reports to experts to check for accuracy and we were not sure how this might affect our confidence in the results.
Evidence from these trials is insufficient to establish whether inhaled corticosteroids are beneficial in cystic fibrosis, but withdrawal in those already taking them has been shown to be safe. There is some evidence they may cause harm in terms of growth. It has not been established whether long-term use is beneficial in reducing lung inflammation, which should improve survival, but it is unlikely this will be proven conclusively in a randomised controlled trial.
Reduction of lung inflammation is one of the goals of cystic fibrosis therapy. Inhaled corticosteroids are often used to treat children and adults with cystic fibrosis. The rationale for this is their potential to reduce lung damage arising from inflammation, as well as their effect on symptomatic wheezing. It is important to establish the current level of evidence for the risks and benefits of inhaled corticosteroids, especially in the light of their known adverse effects on growth. This is an update of a previously published review.
To assess the effectiveness of taking regular inhaled corticosteroids, compared to not taking them, in children and adults with cystic fibrosis.
We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register, comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. We requested information from pharmaceutical companies manufacturing inhaled corticosteroids and authors of identified trials.
Date of most recent search of the Group's Trials Register: 15 August 2016.
Randomised or quasi-randomised trials, published and unpublished, comparing inhaled corticosteroids to placebo or standard treatment in individuals with cystic fibrosis.
Two independent authors assessed methodological quality and risk of bias in trials using established criteria and extracted data using standard pro formas.
The searches identified 34 citations, of which 26 (representing 13 trials) were eligible for inclusion. These 13 trials reported the use of inhaled corticosteroids in 506 people with cystic fibrosis aged between six and 55 years. One was a withdrawal trial in individuals who were already taking inhaled corticosteroids. Methodological quality and risk of bias were difficult to assess from published information. Many of the risk of bias judgements were unclear due to a lack of available information. Only two trials specified how participants were randomised and less than half of the included trials gave details on how allocation was concealed. Trials were generally judged to have a low risk of bias from blinding, except for two which were open label or did not use a placebo. There were some concerns that a number of trials had not been published in peer-reviewed journals, but the risk of bias from this was unclear. Inclusion criteria varied between trials, as did type and duration of treatment and timing of outcome assessments. Objective measures of airway function were reported in most trials but were often incomplete. Significant benefit has not been conclusively demonstrated. Four trials systematically documented adverse effects and growth was significantly affected in one study using high doses.