P051 Real-world Experience of Change in Lung Clearance Index (LCI2.5) Following Initiation of Elexacaftor/tezacaftor/ivacaftor in Children with Cystic Fibrosis Aged 6 Through 11

Objectives: Elexacaftor/tezacaftor/ivacaftor (ETI) was licensed for use in Scotland in January 2022 for children aged between 6–11 years with CF and any FDA approved mutation combination. This single-centre, cohort study aimed to analyse the effects of ETI on lung health (LCI2.5) as well as spirometry and growth measures. Methods: Baseline data prior to commencing ETI were collected for children with CF including anthropometric data, spirometry data (Masterscreen, Carefusion) and LCI2.5 by nitrogen multiple breath washout (N2-MBW, Exhalyser-D device). These measurements were then repeated after 3 months of ETI treatment. Results: Data are available for 11 children (8 male), of whom 4 were modulator naïve and 7 had transitioned from prior modulator treatment (3 from Ivacaftor and 4 from Symkevi). Table 1Mean (range) for selected baseline demographics prior to starting ETI (n = 11) are shownVariableMean (range)Age10.2 (7–12)LCI2.56.9 (5.8–8.9)FEV1 (% predicted)97 (74–122)BMI19.1 (16.1–26) Open table in a new tab Table 2Mean (sd) differences in clinical parameters before and after ETI therapyPre-ETIPost-ETIMean (sd) changep-value*Student's paired t-testLCI2.56.9 (1)6.4 (0.3)−0.52 (0.9)0.09FEV1 (% predicted)96.9 (14.1)101 (12.3)+4.2 (9)0.18FEV1 (z score)−0.3 (1.2)+0.1 (1.1)+0.35 (0.8)0.22BMI19.1 (3.6)19.9 (3.9)+0.8 (1.1)0.04* Student's paired t-test Open table in a new tab Differences in clinical parameters before and after starting ETI are displayed in Table 2. Conclusions: Trends towards improvements in LCI2.5 and lung function were seen along with statistically significantly increased BMI after institution of ETI therapy in children aged 6–11 years. The data align with trial data, with small sample size and good level of baseline lung health being the likely reasons for not achieving significant changes in LCI2.5.