Cystic fibrosis causes frequent lung infection and the airways become blocked with mucus. This in turn leads to inflammation, which causes more lung damage and more mucus to be produced. Corticosteroids are strong drugs given to treat this inflammation. The review includes four trials; one for six weeks, one for 12 weeks and two with four-year follow up. We could only combine data for one outcome at one time-point. Trials showed that oral steroids of 1mg/kg to 2 mg/kg (prednisolone equivalent) given every other day seemed to slow the advance of lung disease. However, there are serious adverse effects such as cataracts and the slowing of growth at the higher dose. These led to one trial stopping early. Follow-up data show that catch-up growth started two years after treatment ceased. Treatment must use the lowest effective dose and the shortest duration of therapy to reduce the risk of a permanent effect on growth. A dose of 1 mg/kg on alternate days might be considered for up to 24 months, but close attention should be paid to adverse effects. The short-term use of oral steroids should be better assessed but may also be associated with adverse effects.
In order to assess the risk of bias in the included studies, we followed the guidance given in the Cochrane Handbook for Systematic Reviews of Interventions ( Higgins 2009 ). We considered such aspects as generation of randomisation sequence and allocation concealment. If we regarded these as adequately performed, then there was a low risk of bias to the study; if we regarded these as inadequately performed, then there was a high risk of bias to the study; and if they were considered unclear then the risk of bias was unclear too. We also considered the degree of blinding and the risk of bias increased as the number of people blinded to the intervention decreased. Finally, we considered whether issues resulting from incomplete outcome data were adequately addressed and whether this led to a low, high or uncertain risk of bias.