Decreased Lymphocytic Bronchitis Severity in the Era of Azithromycin Prophylaxis

• Published in: The Journal of heart and lung transplantation Vol. 41; no. 4; pp. S310 - S311
• Main Authors: Santos, J., Hays, S., Golden, J.A., Calabrese, D., Kolaitis, N.A., Kleinhenz, M., Rupal, S., Venado, A., Leard, L.E., Kukreja, J., Singer, J.P., Greenland, J.R.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.04.2022
• ISSN: 1053-2498; 1557-3117
• DOI: 10.1016/j.healun.2022.01.769

Large-airway lymphocytic inflammation (LB), assessed on endobronchial biopsies, has been associated with acute cellular rejection and chronic lung allograft dysfunction (CLAD). Azithromycin (AZI) prophylaxis has been proposed to prevent airway inflammation and subsequent CLAD, but trial results have been mixed. We hypothesized that AZI prophylaxis would be associated with reduced LB and increased free survival improved CLAD-free survival. Our center implemented AZI prophylaxis on 1/1/2011, while in 2016, routine endobronchial biopsies were discontinued. Thus, we compared frequencies of LB from endobronchial biopsies from in the pre-AZI era (1/1/2005 -1/1/2011), with those during AZI prophylaxis (1/1/2011-12/31/2015). LB was classified as none, minimal, mild, or moderate by histopathological analysis. Rates of each LB severity were compared using ordinal mixed model regression. The effect of AZI prophylaxis on CLAD free survival was assessed by a Cox proportional hazards model. Both models were adjusted for age, sex, ethnicity, indication, transplant type, lung allocation score, and CMV serology. Subject characteristics were similar for the 1,344 biopsies performed on 153 subjects before AZI prophylaxis and the 975 biopsies on 178 subjects in the AZI prophylaxis era, except that the AZI group was older. Biopsies in the AZI era had a 1.6 (95% CI 1.2-2.3, P = 0.004)-fold odds of having a lower LB grade (Figure A). Subjects in the AZI era had a 1.3 (95% CI 0.7-2.0, P = 0.45)-fold increased risk of CLAD or death (Figure B). LB was less common in the era of AZI prophylaxis, potentially representing a direct effect of AZI or reflecting other changes in practice. Despite decreased rates of LB, CLAD-free survival did not improve. New tools are needed to detect antecedents of CLAD and guide therapies.