Changes in factors associated with inhaled antibiotic prescriptions for people with cystic fibrosis over time in the U.S.

Rationale: CF care guidelines recommend chronic inhaled antibiotics for chronic Pseudomonas aeruginosa (Pa) lung infection. These medications are costly, time consuming and prescription needs may change with improved outcomes.

Objectives: We determined the proportion of pwCF with chronic, intermittent or negative Pa infection categories, their clinical and demographic characteristics, factors associated with inhaled antibiotic prescription and changes between 2011 and 2019.

Methods: This cohort study using the U.S. CF Foundation patient registry for pwCF >2 years, no prior lung transplant, and with ≥3 respiratory cultures/year determined chronic inhaled antibiotics (≥3 months per calendar year) and Pa infection status from encounter level data. Outcomes and odds of prescription for relevant clinical factors were evaluated using generalized estimating equation models with additional interaction between the predictor and the calendar year to examine changes of predictors over time.

Results: Proportion of pwCF with chronic and intermittent Pa decreased and antibiotic prescription rates increased for these groups and decreased for Pa negative pwCF. Hispanic ethnicity, female sex, pancreatic insufficiency, CF diabetes, and ivacaftor/lumacaftor were associated with higher antibiotic prescriptions for each Pa status. Among Pa-negative pwCF prescriptions were higher with Burkholderia spp. (1.17, (CI₉₅ 1.03,1.34)) or MRSA (OR 1.45, (1.26,1.68)) but decreased between 2011 and 2019. For Aspergillus OR increased to 1.6,(1.3,1.8) in 2019. Prescriptions for pwCF on ivacaftor decreased, becoming lower in 2019 for chronic (OR 0.7, (0.5,0.8)) and Pa-negative pwCF (OR 0.7, (0.5,0.8)).

Conclusions: Factors predicting inhaled antibiotic prescription differed between 2011 and 2019 indicating changes in health and care for pwCF even prior to triple-modulators.