University of Michigan
Department of Pediatrics
Evidence-Based Pediatrics Web Site

Question

• Does azithromycin improve pulmonary function in cystic fibrosis patients colonized with Pseudomonas aeruginosa?

Clinical Bottom Lines

1. Twenty-four weeks of azithromycin therapy in cystic fibrosis patients colonized with P. aeruginosa resulted in a statistically significant improvement in FEV₁ % predicted compared to placebo.¹
2. Additionally, patients who received azithromycin had less of a risk of experiencing a CF exacerbation compared to those who received placebo.
3. Currently, the Pediatric Pulmonologists at the University of Michigan are starting lifelong azithromycin therapy in cystic fibrosis patients as soon as they become colonized with Pseudomonas aeruginosa.
   

Summary of Key Evidence

1. The article appraised is a randomized, double-blind, placebo-controlled trial in which 87 CF patients older than 6 years of age, colonized with P. aeruginosa, with FEV₁ > 30% predicted received 250mg of azithromycin po Monday, Wednesday, Friday (500mg if > 40kg) for 24 weeks while 98 received placebo.¹
2. Exclusion criteria included colonization with B. cepacia or nontuberculous mycobacteria, GI manifestations of cystic fibrosis, or recent initiation of concomitant therapies like tobramycin nebs, oral steroids, antibiotics, or pulmozyme.
3. The primary outcome evaluated was the change in FEV₁% predicted. Secondary outcomes included changes in: body weight, time until first pulmonary exacerbation, number of pulmonary exacerbations, hospitalization rates, use of nonquinolone antibiotics, inflammatory markers, and quality of life.
4. The improvement of FEV₁% predicted in the azithromycin group was established by 28 days of therapy but returned to pre-treatment levels 4 weeks after treatment was discontinued.
5. The azithromycin group was found to have more occurrences of wheezing, nausea, and diarrhea than the placebo group.
6. There was little difference between the azithromycin group and the placebo group in emergence or eradication of multidrug resistant strains of P. aeruginosa or nontuberculous mycobacteria.
7. Another randomized, double-blind, placebo-controlled, crossover trial of azithromycin in children with cystic fibrosis found a median relative difference in FEV₁ between azithromycin and placebo of 5.4%.²
   

Additional Comments

• Investigation of azithromycin use in CF patients came about because of results from studies of macrolide use in patients with diffuse panbronchiolitis. One study showed improvement of 10 year survival in patients with diffuse panbronchiolitis from 12.4% to more than 90% with macrolide therapy.³ Diffuse panbronchiolitis is a chronic pulmonary disease with clinical symptoms of chronic cough, mucopurulent sputum, dyspnea, wheezing, and airflow obstruction, much like cystic fibrosis.
• Evaluation of treatment effects and safety beyond 24 weeks needs to be further investigated.
• The efficacy of azithromycin in patients colonized with B. cepacia or in those not colonized with P. aeruginosa is not known.
• The emergence of macrolide-resistant oral flora and nontuberculous mycobacteria needs to be monitored.
  

Citation

1. Saiman L, Marshall B, Mayer-Hamblett N, et al. Azithromycin in patients with cystic fibrosis chronically infected with Pseudomonas aeruginosa. JAMA. 2003;290:1749-1756
2. Equi A, Balfour-Lynn IM, Bush A, et al. Long term azithromycin in children with cystic fibrosis. Lancet 2002;360:978-84.
3. Nagai H, Shishido H, Yoneda R, et al. Long-term low-dose administration of erythromycin to patients with diffuse panbronchiolitis. Respiration 1991;58:145-9.
   

CAT Author: Rosanne Kason, MD

CAT Appraisers: John Frohna, MD

Date appraised: March 31, 2004