Effect of Azithromycin on Pulmonary Function in Patients With Cystic Fibrosis Uninfected With Pseudomonas aeruginosa A Randomized Controlled Trial

Context Azithromycin is recommended as therapy for cystic fibrosis (CF) patients with chronic Pseudomonas aeruginosa infection, but there has not been sufficient evidence to support the benefit of azithromycin in other patients with CF. Objective To determine if azithromycin treatment improves lung function and reduces pulmonary exacerbations in pediatric CF patients uninfected with P aeruginosa. Design, Setting, and Participants A multicenter, randomized, double-blind placebo-controlled trial was conducted from February 2007 to July 2009 at 40 CF care centers in the United States and Canada. Of the 324 participants screened, 260 were randomized and received study drug. Eligibility criteria included age of 6 to 18 years, a forced expiratory volume in the first second of expiration (FEV1) of at least 50% predicted, and negative respiratory tract cultures for P aeruginosa for at least 1 year. Randomization was stratified by age of 6 to 12 years vs 13 to 18 years and by CF center. Intervention The active group (n=131) received 250 mg (weight 18-35.9 kg) or 500 mg (weight >= 36 kg) of azithromycin 3 days per week (Monday, Wednesday, and Friday) for 168 days. The placebo group (n=129) received identically packaged placebo tablets on the same schedule. Main Outcome Measures The primary outcome was change in FEV1. Exploratory outcomes included additional pulmonary function end points, pulmonary exacerbations, changes in weight and height, new use of antibiotics, and hospitalizations. Changes in microbiology and adverse events were monitored. Results The mean (SD) age of participants was 10.7 (3.17) years. The mean (SD) FEV1 at baseline and 168 days were 2.13 (0.85) L and 2.22 (0.86) L for the azithromycin group and 2.12 (0.85) L and 2.20 (0.88) L for the placebo group. The difference in the change in FEV1 between the azithromycin and placebo groups was 0.02 L (95% confidence interval [CI], -0.05 to 0.08; P=.61). None of the exploratory pulmonary function end points were statistically significant. Pulmonary exacerbations occurred in 21% of the azithromycin group and 39% of the placebo group. Participants in the azithromycin group had a 50% reduction in exacerbations (95% CI, 31%-79%) and an increase in body weight of 0.58 kg (95% CI, 0.14-1.02) compared with placebo participants. There were no significant differences between groups in height, use of intravenous or inhaled antibiotics, or hospitalizations. Participants in the azithromycin group had no increased risk of adverse events, but had less cough (-23% treatment difference; 95% CI, -33% to -11%) and less productive cough (-11% treatment difference; 95% CI, -19% to -3%) compared with placebo participants. Conclusion In children and adolescents with CF uninfected with P aeruginosa, treatment with azithromycin for 24 weeks did not result in improved pulmonary function.