A randomised controlled trial of azithromycin therapy in bronchiolitis obliterans syndrome (BOS) post lung transplantation

Background We conducted a placebo-controlled trial of azithromycin therapy in bronchiolitis obliterans syndrome (BOS) post lung transplantation. Methods We compared azithromycin (250 mg alternate days, 12 weeks) with placebo. Primary outcome was FEV1 change at 12 weeks. Results 48 patients were randomised; (25 azithromycin, 23 placebo). It was established, post randomisation that two did not have BOS. 46 patients were analysed as intention to treat (ITT) with 33 'Completers'. ITT analysis included placebo patients treated with open-label azithromycin after study withdrawal. Outcome The ITT analysis (n=46, 177 observations) estimated mean difference in FEV1 between treatments (azithromycin minus placebo) was 0.035 L, with a 95% CI of -0.112 L to 0.182 L (p=0.6). Five withdrawals, who were identified at the end of the study as having been randomised to placebo (four with rapid loss in FEV1, one withdrawn consent) had received rescue open-label azithromycin, with improvement in subsequent FEV1 at 12 weeks. Study Completers showed an estimated mean difference in FEV1 between treatment groups (azithromycin minus placebo) of 0.278 L, with 95% CI for the mean difference: 0.170 L to 0.386 L (p=<0.001). Nine of 23 ITT patients in the azithromycin group had >= 10% gain in FEV1 from baseline. No patients in the placebo group had >= 10% gain in FEV1 from baseline while on placebo (p=0.002). Seven serious adverse events, three azithromycin, four in the placebo group, were deemed unrelated to study medication. Conclusions Azithromycin therapy improves FEV1 in patients with BOS and appears superior to placebo. This study strengthens evidence for clinical practice of initiating azithromycin therapy in BOS.