The start of the exacerbation was determined by the earliest date at which a participant concurrently met at least 4 of the 12 modified Fuchs symptoms/signs; discontinued from the study early; died; or received an antipseudomonal agent for an event that did not meet modified Fuchs criteria but was determined to be an exacerbation by the Blinded Exacerbation. Fuchs symptoms/signs; * Change in sputum * New or increased hemoptysis * Increased cough * Increased dyspnea * Malaise, fatigue or lethargy * Temperature above 38oC * Anorexia or weight loss * Sinus pain or tenderness * Change in sinus discharge * Change in physical examination of the chest * Decrease in pulmonary function by 10 percent or more from a previously recorded value * Radiographic changes indicative of pulmonary infection Median and 95%Ci were estimated using Kaplan Meier estimates.