Kristina Vermeersch,1 Maria Gabrovska,2 Griet Deslypere,3 Ingel K Demedts,4 Hans Slabbynck,5 Joseph Aumann,3 Vincent Ninane,2 GeertM Verleden,1 Thierry Troosters,1,6 Kris Bogaerts,7,8 Guy G Brusselle,9 Wim Janssens1 On behalf of the BACE Trial Investigators 1KU Leuven, Laboratory of Respiratory Diseases, Department of Clinical and Experimental Medicine, Faculty of Medicine, Leuven, Belgium; 2Department of Pneumology, Centre Hospitalier Universitaire Saint-Pierre, Brussels, Belgium; 3Department of Pneumology, Jessa Ziekenhuis, Hasselt, Belgium; 4Department of Respiratory Medicine, AZ Delta Roeselare-Menen, Roeselare, Belgium; 5Department of Respiratory Medicine, ZNA Middelheim, Antwerpen, Belgium; 6KU Leuven, Department of Rehabilitation Sciences, Faculty of Kinesiology and Rehabilitation Sciences, Leuven, Belgium; 7KU Leuven, Department of Public Health and Primary Care, I-BioStat, Leuven, Belgium; 8Hasselt University, Hasselt, Belgium; 9Department of Respiratory Medicine, Ghent University Hospital, Ghent, Belgium Background: Long-term use of macrolide antibiotics is effective to prevent exacerbations in chronic obstructive pulmonary disease (COPD). As risks and side effects of long-term intervention outweigh the benefits in the general COPD population, the optimal dose, duration of treatment, and target population are yet to be defined. Hospitalization for an acute exacerbation (AE) of COPD may offer a targeted risk group and an obvious risk period for studying macrolide interventions.Methods/design: Patients with COPD, hospitalized for an AE, who have a smoking history of ≥10 pack-years and had ≥1 exacerbation in the previous year will be enrolled in a multicenter, randomized, double-blind, placebo-controlled trial (NCT02135354). On top of a standardized treatment of systemic corticosteroids and antibiotics, subjects will be randomized to receive either azithromycin or placebo during 3months, at an uploading dose of 500mg once a day for 3days, followed by a maintenance dose of 250mg once every 2days. The ...