Methods
A database of all PwCF on ETI therapy was cross-referenced to a bronchoscopy database to identify individuals who underwent bronchoscopy with BAL while on ETI therapy. Procedures performed while the individual was on intravenous antibiotics were excluded, as were procedures where pulmonary exacerbation was the indication. Individuals were excluded from further analysis if they did not have at least one bronchoscopy performed while not on ETI therapy within 5 years of the index procedure. Clinical information including demographics and CFTR genotype, indication for bronchoscopy, as well as BAL findings including culture data, cell count, neutrophil count and neutrophil percentage were abstracted from the medical record. Pathogen positive cultures were defined as growth of any potentially pathogenic organism on culture. Statistical analysis was performed using GraphPad Prism using paired T-tests (continuous data) or Fisher exact test (dichotomous data). Neutrophil cells counts were log transformed prior to analysis. The study was approved by the UNC IRB (#21-1137).