2.4.2 short- and mid-term repeatability (within 15 minutes and
24 hours)
As previously described, for short- and mid-term repeatability of LCI,
MBW measurements were performed in triplicates 15 minutes and 24 hours
apart respectively, with unchanged measurement conditions in school-aged
children with CF 17,18. We used mixed-effects linear
regression models to calculate the variability in LCI between
measurements allowing for correlation of repeated measurements within
individuals. We used mean difference, intercept, and residual standard
deviation to calculate the coefficient of variation (CV%), intraclass
correlation coefficient (ICC), and coefficient of repeatability (CR).
Based on a log-linear model, we calculated upper limit of normal (ULN)
for relative differences (95% quantile of a normal distribution)
indicating a threshold below which 95% of the relative differences are
expected to fall.