Efficacy of Azithromycin for Treatment of Acute Exacerbation of Chronic Fibrosing Interstitial Pneumonia: A Prospective, Open-Label Study with Historical Controls

Background: Acute exacerbation of chronic fibrosing interstitial pneumonia (AE-CFIP) is an often fatal condition with no established treatment. Recently, macrolides were found to be beneficial in cases of acute lung injury. Objectives: To examine the clinical effectiveness and safety of intravenous azithromycin in patients hospitalized for AE-CFIP. Methods: A prospective, open-label study with historical controls was conducted. Twenty consecutive patients with AE-CFIP received azithromycin. They were compared with a historical cohort treated with fluoroquinolone (n = 56). All patients received high-dose steroid pulse therapy. The primary end point was mortality at 60 days. The secondary end point was safety of intravenous azithromycin in patients with AE-CFIP. Inverse probability of treatment weighting (IPTW) using the propensity score was performed to investigate the relationship between azithromycin use and survival time. Results: Mortality was significantly lower in the patients treated with azithromycin than in those treated with fluoroquinolone (mortality rate at 60 days: 20 vs. 69.6%, p < 0.001; median survival time: not reached vs. 29.5 days, p < 0.001). The IPTW adjusted hazard of mortality at 60 days in patients receiving azithromycin was 0.17 (95% CI 0.05-0.61). No serious adverse events were observed. Conclusions: Azithromycin was associated with improved outcomes in patients with AE-CFIP. Further studies are needed to verify this finding (Clinical trial JMA-IIA00095).