Height Velocity in Pediatric Cystic Fibrosis Under Triple CFTR Modulator Therapy: A Real-Life Monocentric Experience

Abstract

Background/Objectives: Cystic fibrosis (CF) is a multi-system disorder characterized by chronic respiratory failure, malnutrition, and impaired growth. Achieving linear growth above the 50th percentile is associated with better pulmonary outcomes. Since October 2022, Elexacaftor/Tezacaftor/Ivacaftor (ETI) has been approved in Italy for children aged ≥6 years. However, data on its impact on height velocity (HV) remain lacking. This study aims to evaluate growth patterns by HV and explore differences according to the CFTR variant genotype. Methods: We conducted a prospective single-center study at the CF Unit of Bambino Gesù Children’s Hospital involving 24 children aged 6–11 years eligible for ETI treatment. Baseline assessments included height, weight, body mass index (BMI), bone mineral density (BMD), body composition (via bioelectrical impedance analysis, BIA), and muscle strength (one-minute sit-to-stand test (1STST)). Height, weight, HV, and BMI standard deviation scores (SDS) were calculated for the 6 months before and after ETI initiation. Results: The mean age of the cohort was 8.7 ± 1.9 years (F/M: 12/12), with most patients naïve to CFTR modulators. A significant increase in HV was observed post-ETI: from 4.2 ± 2.0 cm/year (−1.96 ± 2.4 SDS) in the 6 months before treatment to 7.1 ± 3.0 cm/year (+1.5 ± 3.7 SDS) after treatment initiation (p < 0.0001). Patients with F508del/minimal function (F/MF) genotypes (n = 11) showed significantly greater HV compared to those with F508del/F508del (F/F, n = 5) and F508del/residual function (F/RF, n = 8) genotypes (p < 0.0001). No significant differences were observed among genetic groups in baseline BMD or lean mass. Conclusions: ETI treatment significantly and rapidly improves HV in children with CF, particularly in those with F/MF genotypes. These findings underscore the role of CFTR modulator therapy in promoting linear growth, a key indicator of health in pediatric CF populations.