Impact of elexacaftor/tezacaftor/ivacaftor on utilization of routine therapies in cystic fibrosis: Danish nationwide register study

Background: Elexacaftor/tezacaftor/ivacaftor (ETI) has been effective in improving several outcomes in people living with cystic fibrosis (pwCF). Although clinical guidance regarding maintenance therapies has not changed, staff reports indicate that individuals reduce some therapies. This study aimed to evaluate ETI's effect on utilization of routine therapies among pwCF in Denmark. Methods: We included all pwCF initiating ETI between 1 September 2020 and 31 October 2022. Utilization of routine therapies was analysed by drug class (e.g., gastrointestinal medications) and individual treatments (e.g., pancreatic enzymes) before and after ETI initiation using national registry data. Odds ratios (ORs) for prescription redemptions pre- and post-ETI were calculated to assess ETIs impact on the use of routine therapies. Results: The study population consisted of 351 individuals. Median age was 23 years (IQR 14–32) and mean ppFEV₁ was 76 (SD 22) at index. Two-year follow-up was available for 205 individuals. Two years post ETI initiation, the one-year prevalence was reduced for airway medications, (89.5 % to 75.1 %) and inhaled antibiotics (59.5 % to 42.9 %.). OR for redeeming a prescription two years post-ETI initiation (95 % CI) was reduced for four out of five drug classes: airway medications (OR: 0.24 [0.19; 0.29]), inhaled antibiotics (OR: 0.28 [0.2; 0.39]), oral antibiotics (OR: 0.49 [0.41; 0.58]), gastrointestinal medications (OR: 0.66 [0.57; 0.77]). Conclusion: Two years after ETI initiation, reductions in the use of several routine therapies were observed in a national cohort of pwCF, with the largest declines in airway medications and antibiotics. These findings highlight ETI's real-world impact beyond conventional clinical metrics.