CF Medication Utilization and Lung Function
As prior data has suggested that discontinuation of Dorn or HTS may not alter lung function in PwCF on ETI, we examined relationships between changes in lung function (slope ppFEV1) and changes in MPR for various medications. Among 112 PwCF with sufficient lung function data pre- and post-ETI, average ppFEV1increased significantly in the post-ETI period (74.5±24.4% pre-ETI, 82.6±25.0% post-ETI, p<0.001). In the pre-ETI period, lung function declined slowly over time (slope ppFEV1 ‐0.8 ± 5.0%/year). In the post-ETI period, change in FEV1 over time remained negative (slope ppFEV1 ‐1.5 ± 6.1%/year) and was not statistically distinguishable from the pre-ETI period (p=0.34). While continued decline in lung function could reflect changes in adherence to inhaled medications, PwCF who had lung function decline post ETI (negative ppFEV1 slopes) had similar MPRs for Dorn and HTS to those with preserved or improving lung function (positive slopes) (Fig 1B ). As an alternative analysis, ppFEV1 slope did not correlate with changes in MPR for Dorn or HTS (Fig. 1C ). To account for possible confounding factors, we performed a multivariate analysis including age, initial ppFEV1, and prior modulator use in the model along with changes in MPR for Dorn and HTS. Although age at start of ETI was correlated with slope ppFEV1 post-ETI (r=0.4, p=0.02) in univariate analysis, no variables were significantly correlated in multivariate analysis.