Evidence of Small Airways Disease and the Immediate Effects of Lumacaftor/Ivacaftor in Children with Cystic Fibrosis.

Aim The aim of this study was to explore risk factors for acute changes in lung function following initiation of lumacaftor/ivacaftor (LUM/IVA) in children with cystic fibrosis. Methods Retrospective review of all children commenced on LUM/IVA treatment over a one-year period. CT Thorax images were reviewed for evidence of air trapping using the Brody score. Results Data was collected from 15 children. A transient decline in ppFEV1 was observed after initiation of LUM/IVA in 93% (n=14) of patients with an absolute mean decline of -10.8%. There was a statistically significant inverse relationship between ΔFEV1 and baseline ppFEV1. There was no relationship between air trapping score and ΔFEV1 (p=0.41). Conclusion Pre-existing small airways disease is not a risk factor for acute changes in lung function following initiation of LUM/IVA. Our results suggest that a LUM/IVA-related decline in lung function is more significant in CF children with higher baseline FEV1.