Nichols DP, Odem-Davis K, Cogen JD, et al. - Researchers performed this retrospective cohort analysis utilizing the US cystic fibrosis Foundation Patient Registry, to assess pulmonary outcomes in chronic azithromycin users with cystic fibrosis vs matched controls over years of use and considered combined azithromycin use in cohorts using chronic inhaled tobramycin or aztreonam. They performed predefined sensitivity analyses taking into account lung function, Pseudomonas aeruginosa (PA) status, and follow-up time intervals. They noted approximately 40% less FEV₁% predicted per-year decline in those with PA using azithromycin vs matched controls, across 3 years. No difference was evident in this rate of decline depending on azithromycin use in those without PA. In all cohorts, no difference was seen in the use of intravenous antibiotics between azithromycin users and controls. FEV₁% predicted per-year drop of −0.16 was noted in users of inhaled tobramycin and azithromycin vs nonusers, whereas a mean 0.49% predicted per year slower decline was observed in users of inhaled aztreonam lysine and azithromycin vs matched controls. The added rationale for chronic azithromycin use in PA-positive patients to decrease lung function deterioration was afforded by the findings.