Prednisone in Cystic Fibrosis Pulmonary Exacerbations

This will be a 5 year randomized, double blind, placebo controlled trial of 7 days of oral prednisone in cystic fibrosis (CF) patients receiving intravenous (IV) antibiotic treatment for a pulmonary exacerbation at the Hospital for Sick Children and other study sub-sites across Canada. The intervention will be oral prednisone 2 mg/kg/day (max 60 mg) divided twice daily for 7 days as an adjunctive therapy for pulmonary exacerbations in CF patients who have not recovered their baseline forced expiratory volume in 1 second (FEV1) after 7 days of IV antibiotic treatment. The primary outcome will be the proportion of subjects who achieve \>90% of their baseline FEV1 % predicted at day 14 of IV antibiotic treatment for a pulmonary exacerbation in each treatment arm.