Statistical analyses
For baseline characteristics, we used descriptive statistics. For
comparisons of LFT results 0-3 months before and 3-4 months after
scoliosis surgery, a Wilcoxon-signed rank test was used. To investigate
the trend of function decline, linear mixed effects models were fitted,
which included a random intercept and random slope for time per
individual. We introduced a linear spline for time (both fixed as
random) with one knot at the time of surgery. Subsequently, we
determined the rate of progression before and after surgery. Confidence
intervals were estimated using bootstrapping (n =1000) and
significance tests were based on the likelihood ratio test.
Results