P062 The impact of elexacaftor/tezacaftor/ivacaftor on adherence to inhaled medication in adults with cystic fibrosis: a 3-centre study in Greece

Objective: To compare adherence to inhaled medications before and after elexacaftor/tezacaftor/ivacaftor (ETI) initiation Methods: Adults with CF from 3 centers in Greece who had completed one year on ETI 2022 participated in the study. Adherence was assessed by the Medication Possession Ratio (MPR), i.e the ratio of the number of doses received from the pharmacy to the number of advised doses in one year. Adherence data on dornase-α, tobramycin, colistin, aztreonam and levofloxacin during the year on ETI, i.e. June 1st 2021- May 31st 2022 were compared to data during the year June 1st 2019 -May 31st 2020, before ETI initiation. Results: 38 women and 33 men, 46 F508del homozygotes and 25 heterozygotes - mean age 31.8 ± 9.2 years- were included. After ETI initiation significant improvement was observed in weight (58.0 ± 10.9Kg before vs 62.1 ± 10.9Kg, p < 0.001), FEV1% predicted (47.5 ± 19.8% before vs 57.1 ± 21.8% after, p < 0.001) and FVC% predicted (66.4 ± 22.3% before vs 78.4 ± 21.6% after, p < 0.001). MPR for dornase-α statistically significantly decreased from 67 ± 35% to 48 ± 40% (p < 0.001). MPR for each inhaled antibiotic also decreased with statistical significance for tobramycin, aztreonam and colistin. MPR for all 4 antibiotics decreased from 62 ± 33% to 41 ± 37% (p < 0.001) as did MPR for all inhaled medication (63 ± 31% vs 43 ± 36%, p < 0.001). Difference in MPR for dormase-α, each inhaled antibiotic, all inhaled antibiotics together and all inhaled medication did not differ according to gender, F508del status, presence of diabetes or isolation of P. aeruginosa. Difference in MPRs was not related to age, ETI duration, difference in FEV1, FVC, days of hospitalization or number of exacerbations. The only exception was the MPR of colistin which was positively related to the FEV1 difference (r = 0.455, p = 0.022). Conclusion: Adherence to dornase-α and inhaled antibiotics has been significantly reduced after ETI initiation despite lack of data on the safety of treatment discontinuation.