C61-11 Impact of Elexacaftor-Tezacaftor-Ivacaftor on Children’s Height

Rationale Elexacaftor-tezacaftor-ivacaftor (ETI) has transformed cystic fibrosis (CF) care, improving pulmonary outcomes and quality of life. Growth impairment is a pervasive CF complication. Improving childhood growth correlates with better pulmonary health. While ETI is linked to gains in weight and BMI in children, its impact on height remains unclear. This study examines within-patient changes in height, weight, and BMI among children with CF who initiate ETI, and compares them to children who do not. We hypothesize that ETI initiation leads to height improvements. Methods A retrospective cohort study of children aged 4-12 receiving care at Riley Hospital who are ETI eligible. Inclusion criteria included at least 12 months of follow-up before and after ETI initiation, and 12 months of ETI use. Growth changes were assessed by comparing the median height, weight, and BMI CDC z-scores per quarter in the 8 quarters before and after the ETI initiation anchoring date. The non-ETI cohort’s anchoring date was based on patient age at ETI approval. Linear models were used to determine mean growth regression parameters. Results Of 117 patients, 102 received ETI and 15 did not. A higher proportion of ETI patients experienced a height z-score improvement of 0.1 or more when compared to the non-ETI group (44.6% to 13.3%). Linear models analyzing the median z-scores across the study period indicate that ETI usage was shown to be significantly correlated with an increase in height z-scores when compared to the non-ETI cohort: 0.2 (SE 0.09); p=.0228, after accounting for pre-treatment height. This association was attenuated in a multivariable model: 0.16 (0.10); p=.0913; insurance status, pancreatic sufficiency, and gender were not significantly associated. Conclusion ETI use is significantly correlated with height improvements within 1-2 years of initiation. Height and weight trends suggest clinically meaningful benefits, warranting further study that includes a larger non-ETI comparator cohort.