Baseline chest computed tomography scores correlate with future exacerbations in young children with cystic fibrosis

Background: Children with cystic fibrosis (CF) in early school age have often normal spirometry; more sensitive validated methods for early detection and monitoring of CF lung disease are needed. Aim: To investigate whether chest computed tomography (cCT) score in early school age predicts respiratory tract exacerbation (RTE) number in the following 6 years with better accuracy than FEV1. Methods: Routine cCT obtained in a single centre from 80 CF patients (mean age 8.2; range 4.3-15; mean pred FEV1 83.3%) were scored using CF-cCT scoring system. All patients were closely monitored in the following 6 years, RTE was defined as an intravenous antibiotic treatments for respiratory symptoms. We used Pearson coefficient to describe correlations with lung function parameters (FEV1and FEF25-75) at baseline and after 6 years. Receiver operating characteristic (ROC) curve analysis was used to test a cut off value for CF-cCT score. Results: mean cCT score (sCTtot) and bronchiectasis subscore (sCTbr) were respectively 12.8 and 14.9 (% of max score). Mean number of RTE in 6 years was 2.2 (SD 3.6,range 0-22). We found good correlations between both sCTtot/sCTbr and RTE (R= 0.664 and 0.69 respectively, p<0.001). Baseline FEV1 showed a significant but weaker correlation with RTE in the following 6 years (R=0.49, p<0.001). Baseline FEV1 showed a poor correlation with sCTtot (R=0.424, p<0.001). Area under the ROC curve for sCTbr to detect ≥4 RTE was 0.907. A sCTbr ≥16.9 identified patients who experienced ≥4RTE in the following 6 years with sensitivity 94.1% and specificity 79.4%. Conclusion : Bronchiectasis as diagnosed by cCT identify patients at higher risk of RTE.