One year follow-up of physical activity and health-related quality of life in youth with Cystic Fibrosis in the modulator era.

Elexacaftor/Tezacaftor/Ivacaftor (ETI) has led to major pulmonary and nutritional benefits in youth with cystic fibrosis (YwCF), but its effects on physical activity (PA) and health-related quality of life (HRQoL) remain unclear. This study investigated changes in PA and HRQoL according to modulator trajectory (ETI-naïve, ETI-initiated, ETI-throughout). YwCF aged 6-17 years completed assessments at baseline and follow-up (12-18 months). PA was measured using ActiGraph GT3X + BT accelerometers over seven days. Time in moderate-to-vigorous PA (MVPA) and total PA were converted to sex- and age-specific z-scores calculated from a healthy reference cohort (n = 264). HRQoL was evaluated using the Cystic Fibrosis Questionnaire. Thirty-four YwCF (38% male; 13.1 ± 3.8 years) were included. Changes in MVPA (p = 0.74) and total PA (p = 0.73) did not differ across modulator trajectories. MVPA z-scores increased numerically in all groups, while total PA z-scores remained stable. YwCF who initiated or already received ETI reported lower treatment burden and fewer respiratory symptoms, whereas changes in physical functioning varied.ETI did not lead to additional improvements in PA, although improvements were observed in some HRQoL domains. Larger longitudinal studies are required to clarify mechanisms underlying PA and HRQoL in the modulator era.