PE was defined as having 3 or more of these symptoms for at least 48 hours resulting in a physician's decision to prescribe antibiotics: 1. Increased cough 2. Increased sputum volume or change in sputum consistency 3. Increased sputum purulence 4. Increased breathlessness and/or decreased exercise tolerance 5. Fatigue and/or malaise 6. Hemoptysis. A severe pulmonary exacerbation was that required intravenous (IV) antibacterial drug treatment and/or hospitalization. A minimum of 14 days must have occurred between one exacerbation onset and the next. Any exacerbation that occurred less than 14 days from the prior exacerbation was not considered a new exacerbation. Independent adjudication committee with pulmonary physicians adjudicated reported PE events to see if they fulfil the protocol definition. The rate of PE was analyzed using the negative binomial model.

Time to first pulmonary exacerbation was calculated as the number of days from the date of randomization to the date of first documentation of an exacerbation. Pulmonary exacerbation was defined as having 3 or more of the following symptoms for at least 48 hours resulting in a physician's decision to prescribe antibiotics: 1. Increased cough 2. Increased sputum volume or change in sputum consistency 3. Increased sputum purulence 4. Increased breathlessness and/or decreased exercise tolerance 5. Fatigue and/or malaise 6. Hemoptysis A minimum of 4 weeks must have occurred between one exacerbation onset and the next. Any exacerbation that occurred less than 4 weeks from the prior exacerbation was not considered a new exacerbation. The analysis was performed using the stratified log rank test and using Kaplan Meier (KM) curves.