Late Breaking Abstract - Efficacy and safety of azithromycin maintenance therapy in primary ciliary dyskinesia – The BESTCILIA randomized placebo-controlled trial

<b>Introduction:</b> Use of maintenance therapy with the macrolide antibiotic azithromycin (AZI) is increasing in different chronic respiratory disorders incl. primary ciliary dyskinesia (PCD), although no clear evidence exists in PCD. <b>Aims and Objectives:</b> The primary objective was to determine efficacy of AZI maintenance therapy on respiratory exacerbations in PCD. The secondary objectives were to determine efficacy on lung function, health-related quality of life, sputum microbiology, and hearing impairment, and assess safety. <b>Methods:</b> Patients with confirmed diagnosis of PCD, age 7-50 years, were enrolled in this European multi-centre, parallel group, double-blind, randomized, placebo-controlled trial. Participants were randomly assigned to AZI 250/500 mg according to body weight (&lt;/≥ 40 kg) or placebo, 3 times a week for 6 months. <b>Results:</b> A total of 90 participants were randomized - 49 assigned to AZI and 41 to placebo. The AZI group had significant lower rate of exacerbations (rate ratio 0.46, 95%CI: 0.27; 0.80, p=0.006) and pathogenic bacterial species in sputum (rate ratio 0.39, 95%CI: 0.24; 0.64, p=0.0002), compared to the placebo group. There was no significant difference between the treatment groups in lung function, hearing level, or Respiratory symptoms, Sinus symptoms and Ear &amp; hearing symptoms on the quality of life measure. Gastrointestinal complaints were more common in the AZI group. <b>Conclusions:</b> This first multi-national randomized controlled trial on pharmacotherapy in PCD showed that maintenance AZI for 6 months was safe and reduced rate of respiratory exacerbations and rate of pathogenic bacterial species in sputum to less than half.