Correlation between chest CT findings and change in lung function on
CFTR modulating treatment in CF patients
Abstract
Objective: To verify if the extent of structural lung damage visible on
chest CT is correlated with change in ppFEV1 after start of CFTR
modulating therapy in CF patients. Methods: In our retrospective
observational study, we included patients aged ≥6 years starting
ivacaftor or lumacaftor/ivacaftor treatment who were in routine follow
up. FEV1 and BMI were recorded every 3 months. From the group of
patients who had started lumacaftor/ivacaftor, patients were selected
who underwent chest CT within 18 months before or after start of
treatment. Patients who had started ivacaftor all underwent chest CT
just before the start of treatment. These CT scans were reviewed to
determine Brody score. ppFEV1 data was retrieved. To assess
correlations, Spearman R and Pearson R tests were applied. Results:
Thirty patients met the inclusion criteria, with Brody scores between
0.46-55.30 (median: 19.97, normalized score out of 100) and ppFEV1
before treatment of 19-113 (median: 67). Twenty-three and 7 patients had
started lumacaftor/ivacaftor and ivacaftor respectively. Change in
ppFEV1 after 6 months of treatment ranged from -19 to +24 (median: +5).
For patients using lumacaftor/ivacaftor, the correlation between Brody
score and change in ppFEV1 was not significant: Spearman R=-0.213,
(p=0.164), but for patients using ivacaftor, there was a significant
correlation between Brody score and ppFEV1 change, with a Spearman
R=0.679 (p=0.029). Conclusion: The extent of structural damage to the
lungs of CF patients is correlated with the response in ppFEV1 to
ivacaftor, however this correlation was not demonstrable in patients
treated with lumacaftor/ivacaftor.