Reply to Dournes and Benlala: hierarchical computed tomography scoring systems cannot discriminate between reversible bronchiectasis and mucus plugs

In the letter to the Journal by Dournes and Benlala referring to our recent paper, the authors state that hierarchical computed tomography scoring systems cannot discriminate between reversible bronchiectasis and mucus plugs. This is not correct. Existing scoring systems cannot determine whether structural abnormalities in specific airways switch from one hierarchical tag to another between scans; however, scoring systems assess changes for the whole lung or at a lobar level, as opposed to a selected bronchus artery pair. Perth Rotterdam Annotated Grid Morphometric Analysis - Cystic Fibrosis (PRAGMA-CF) has been well validated and proven to be more sensitive to detect and track airway disease in many longitudinal cohort studies than the older, less-developed scoring systems referred to by the authors. The Real World Clinical Outcomes with Novel Modulator Therapy Combinations in People with Cystic Fibrosis (RECOVER) study involved prestudy standardization of scanner imaging outputs from all sites and spirometry control during scanning to standardize lung volumes. Intraclass correlation coefficients in our study for measurements of %Bronchiectasis, %wall thickening, and %Mucus plugging were excellent (>0.8).