Impact of the Lung Clearance Index on clinical decision-making in children with cystic fibrosis

<bold>Background:</bold> The Lung Clearance Index (LCI) is a key outcome measure in paediatric cystic fibrosis (CF) clinical trials. While LCI is used clinically in select European centres, evidence of its utility in informing clinical decisions is an important factor in deciding whether LCI will be adopted more widely. <bold>Methods:</bold> Clinical vignettes were created to assess how providers manage pulmonary exacerbations and adjust inhaled therapies. Two vignettes acted as controls, whereby LCI was not expected to change treatment decisions. Conducted via REDCap®, providers initially used standard clinical data to make treatment decisions, then the LCI result was revealed and they were asked to incorporate LCI into their decision making. <bold>Results:</bold> Overall, 62 providers completed 522 vignettes. Of the 49 providers that completed all 10 vignettes and the demographic questions, 31 were Canadian and 18 were from the US. The majority of providers were CF physicians (37) followed by nurses (5) nurse practitioners (4) and others (3). Overall, LCI changed clinical decisions in 18.4% (95% CI 15.3 - 21.9%), supported decisions in 57.1% (52.7 - 61.3%), and had no impact in 24.5% (21.0 - 28.4%). Of the 104 responses to the control vignettes, LCI changed the decision in 7.7% (3.8 - 14.8%), supported the decision in 77.9% (68.7 - 84.9%) and had no impact in 14.4% (8.8 - 22.7%). <bold>Conclusion:</bold> This simulated study shows that LCI significantly influences treatment decisions in children with CF. These results will inform the design and sample size of a real-world study to demonstrate the impact of LCI-guided care on clinical decision-making and outcomes. This study was supported by the CF Foundation (#RATJEN22A0-LAD)