ABSTRACT
Background: As cystic fibrosis (CF) lung disease progresses, the airways become colonized with opportunistic pathogens such as Pseudomonas aeruginosa secondary to airway surface liquid depletion. Acquisition of P. aeruginosa is associated with decline in lung function and increase in treatment burden and mortality. In October 2019, the Food and Drug Administration approved elexacaftor/tezacaftor/ivacaftor (ELX/TEZ/IVA), a highly effective modulator therapy (HEMT) for individuals aged 12 and older with one copy of the F508del CFTR mutation. ELX/TEZ/IVA increases the amount of and function of CF transmembrane conductance regulator (CFTR) in the respiratory epithelium, increasing mucociliary clearance (MCC) and reducing static airway mucous, a major trigger for chronic infection and inflammation. Method(s): A retrospective analysis of inhaled tobramycin (iTOB) prescriptions prescribed between January 1, 2016, and December 31, 2021, was performed. This captured data before and after ELX/TEZ/IVA approval at Children's Mercy Kansas City (CMKC). The number of individuals with new P. aeruginosa acquisition was determined by identifying electronic prescriptions for iTOB eradication courses. An eradication course was defined as a first lifetime prescription for iTOB or a new prescription for iTOB submitted at least 1 year after a previous prescription. The number of individuals considered chronically infected with P. aeruginosa was determined by identifying individuals receiving chronic iTOB prescriptions and confirmed by respiratory cultures indicating chronic infection based on the Leeds criteria (P. aeruginosa recovered in >=50% of airway cultures in the previous 12 months). Result(s): Eradication courseswere prescribed to 34 individuals in 2016 (15% of people receiving care at CMKC). The number of eradication prescriptions declined in 2020 and 2021, with only 15 (7%) individuals prescribed eradication therapy in 2020 and 12 (5%) in 2021. A similar pattern was observed for prescriptions for chronic infection. In 2016, 57 individuals (25% of our patient population) were receiving iTOB for chronic P. aeruginosa infection. Reductions were seen in 2020 and 2021, with 28 (13%) and 20 (9%) individuals prescribed chronic therapy, respectively. The number of individuals prescribed iTOB for P. aeruginosa eradication and chronic infection per year is represented in Figure 1.(Figure Presented)Conclusions: CMKC experienced a decrease in the number of courses of iTOB prescribed over the last 6 years. HEMT use is associated with greater MCC and anti-inflammatory effects affecting the airway microbiome. The decrease in respiratory cultures growing P. aeruginosa likely reflects these phenomena. A confounding factor is the SARS-CoV-2 pandemic and widespread use of HEMT. Clinic closures and implementation of telemedicine limited in-person patient visits during 2020 and 2021. Despite limited in-person visits, the average number of respiratory cultures per individual at CMKC in 2020 was 3.5, which is consistent with previous years.Wewere able to obtain frequent surveillance cultures through implementation of a drive-through respiratory specimen collection process. Hence, the decrease in number of iTOB courses cannot be attributed to a decrease in frequency of respiratory cultures, although we cannot assess the impact of school closures and a decrease in social gatherings on new P. aeruginosa acquisition or chronic infection. Looking at all these variables, the widespread use of HEMT likely played a significant role in reducing new P. aeruginosa acquisition and chronic P. aeruginosa infection.Copyright © 2022, European Cystic Fibrosis Society. All rights reserved