c) longitudinal changes
Longitudinal changes in LCI were evaluated from a subset of the previously reported cohort including three monthly clinical routine MBW measurements in children with CF aged 3 - 18 years attending routine care between 2014-2018 in our center along with matching clinical information 5. We used a mixed-effects linear regression model to assess the mean rate of change in LCI with age included as a linear term, a participant-specific random intercept and random slope to account for between-participant variability, different observation periods for each participant, and unequal numbers of study visits 21. As previously described5, we used a baseline model and a final model adjusted for predefined clinically most relevant covariates. Next, we assessed all potentially influencing covariates on LCI course first in a univariate analysis and second in the fully adjusted model.