Changes in chronic therapies for cystic fibrosis following initiation of CFTR modulators: A UK retrospective cohort study 2009 - 2023.

INTRODUCTION

People with Cystic Fibrosis have a significant treatment burden from large numbers of maintenance therapies required to manage this multi-organ condition. Currently, there are limited data on the impact of CFTR (Cystic Fibrosis Transmembrane Conductance Regulator) modulator use, including Elexacaftor/Tezacaftor/Ivacaftor (ETI), on prescribing of traditional maintenance therapies in the UK.

METHODS

Retrospective analysis of chronic medications obtained from UK CF registry data, from 2009 to 2023. Impact of starting ETI on maintenance therapies was analysed using descriptive statistics. For those on ETI, risk factors associated with stopping maintenance treatments were identified by logistic regression models, adjusted for age, sex, and percentage predicted FEV1. Socioeconomic status (SES) was determined by Townsend score quintiles.

RESULTS

Overall, chronic medication use decreased for both those prescribed and not prescribed CFTR modulators. Those on ETI, who previously were on dual modulator therapy, had an absolute reduction of 15.1% in inhaled antibiotics, 14.7% in dornase alfa and 9.8% in hypertonic saline by 3 years after ETI initiation. Older age, higher body mass index, and poorer lung function were associated with lower odds of stopping inhaled antibiotics and azithromycin for those on ETI. Those in the lowest SES quintile had significantly lower odds of discontinuing azithromycin (OR:0.61; CI:0.40-0.91) and flucloxacillin (OR:0.54; CI:0.33-0.86), compared to the highest SES quintile.

CONCLUSIONS

Overall, prescriptions of traditional maintenance therapies reduced, irrespective of CFTR modulator use. These data suggest deprescribing may have occurred, despite a limited evidence base to support safe antibiotic withdrawal in this population.