Prompt effect of ELX/TEZ/IVA on the lung function in patients with cystic fibrosis in North Macedonia

<bold>Backround</bold>: Although cystic fibrosis (CF) is a genetic disorder affecting epithelial cells of multiple organs, it is the respiratory tract which is associated with the most significant morbidity. Spirometry is the standard clinical method used to assess lung function. In patients with CF aged > 5 years the percentage predicted (%pred) forced expiratory volume in one second (FEV₁) is the most important indicator of severity of lung disease. <bold>Objective:</bold> The ELX/TEZ/IVA modulator therapy was introduced in our country in 2023. We sought to compare the early impact of therapy on lung function in patients with severe and moderate lung disease respectively. <bold>Methods:</bold> We enrolled 20 subjects aged 8-42 years (mean 22.5) with CF, categorized by FEV₁ into severe (FEV₁≤39%, n=6) and moderate (FEV₁=40–69%, n=14) lung disease groups. Spirometry data were collected at baseline and after one month. Statistical evaluations included paired T-Tests (p<0.05) and regression analysis to explore correlations between initial FEV1 levels and subsequent changes. <bold>Results</bold> After one month of CFTR modulatory therapy, mean FEV1 recorded an increase from the baseline of 12,2 %. The regression analysis correlated that higher initial FEV₁ value predicts better overall outcomes (coefficient 0.71). The severe patients experience bigger absolute gain (mean 16.5, sd 13.43) compared to the moderate group (mean 13.14, sd 8.69). The T-Test results (−6.28, p<0.01) affirm the significance of the FEV₁ improvements. <bold>Conclusion:</bold> In severe lung disease cases, ELX/TEZ/IVA therapy resulted in more pronounced FEV₁ improvement compared to moderate cases.