Comprehensive Evaluation of Elexacaftor/Tezacaftor/Ivacaftor in Paediatric Cystic Fibrosis: Nutritional, Pulmonary, and Quality-of-Life Outcomes

<b>Background/Objectives:</b> Cystic fibrosis transmembrane conductance regulator modulator (mCFTR) therapy has been proven efficacious in controlled clinical trials for individuals with cystic fibrosis. This post-approval retrospective study aimed to determine the comprehensive effects of elexacaftor/tezacaftor/ivacaftor (ETI) on nutritional status, the respiratory system and quality of life over 12 months of clinical use in paediatric patients treatment-naïve to mCFTR. <b>Methods</b>: A retrospective analysis of records of CF adolescents on ETI therapy was conducted. The selected parameters of anthropometric measurements, body composition assessed by BIA, spirometry, and multiple breath nitrogen washout (MBNW) to measure lung clearance index (LCI), were evaluated before therapy and at 3 and 12 months after treatment initiation. Additionally, children completed the Cystic Fibrosis Questionnaire-Revised (CFQ-R). <b>Results:</b> Over 18 months, data from 58 patients (mean age 14.34 ± 1.70, 50% female; 43% homozygous F508del) on ETI were collected. Body weight increased significantly over 12 months, with a mean gain of 3.33 kg at 3 months (<i>p</i> < 0.001) and 7.10 kg at 12 months (<i>p</i> < 0.001), alongside improvements in BMI z-score, fat-free mass, and fat mass. Significant changes (<i>p</i> < 0.001) were also observed after 3 and 12 months in ppFEV₁ (8.91 ± 8.23; 9.67 ± 8.77) and ppFVC (4.46 ± 5.24; 4.61 ± 5.70), with a decrease in LCI (-1.62 ± 2.15; -1.68 ± 1.89). The CFQ-R Respiratory score increased by 11.75 points and correlated with most of the pulmonary and nutritional parameters. <b>Conclusions</b>: In real-world settings, clinical improvement during ETI therapy reflects a comprehensive impact on nutritional status, body composition, pulmonary function, and quality of life for adolescents with CF.