Results
Thirty patients met the inclusion criteria. Brody scores from the CT
scans of these patients ranged from 0.46 to 55.30 (median: 19.97, Q1-Q3:
13.80-26.10) out of 100, and ppFEV1 before treatment
from 19 to 113 (median: 67, Q1-Q3: 36-83.5). Twenty-three patients with
a F508del/F508del genotype had started lumacaftor/ivacaftor, 7 patients
with F508del and a gating mutation on the second allele had started
ivacaftor. Baseline characteristics for both groups are presented in
table 1. Change in ppFEV1 after 6 months of treatment
ranged from -19 to +34 (median: +5.0, Q1-Q3: -4.25 - +13). Median change
ppFEV1 on ivacaftor was +7 (Q1-Q3:+3 - +27) versus +3
(Q1-Q3:-6 - +11) on lumacaftor/ivacaftor. In the lumacaftor/ivacaftor
group, 12 and 11 patients underwent chest CT before and after the start
of treatment, respectively.
Brody score (total score without air trapping) correlated significantly
with baseline ppFEV1 in patients starting
lumacaftor/ivacaftor: Spearman R=-0.514 (p=0.006), Pearson R=- 0.517
(p=0.006).
The correlation between Brody score (total score without air trapping)
and change in ppFEV1 after 6 months was not significant:
Spearman R=-0.213, (p=0.164), Pearson R=-0.057, (p=0.398). Scatterplots
are shown in figure 1.
In patients using ivacaftor, Brody score also correlated significantly
with ppFEV1 at baseline, Spearman R=-0.739 (p=0.029),
Pearson R=-0.734 (p=0.028). Moreover, in this group there was a
significant positive correlation between Brody score and
ppFEV1 change after 6 months, with a Spearman R=0.679
(p=0.029) Pearson R = 0.822 (p=0.012). Scatterplots for these
correlations are shown in figure 2.
As Brody score in this group is correlated with both
ppFEV1 at baseline and ppFEV1 change at
6 months, ppFEV1 at baseline and after 6 months are
expected to be interconnected. Therefore we performed a post-hoc
analysis calculating the correlation coefficient between
ppFEV1 change and Brody score, corrected for
ppFEV1 at baseline. The corrected correlation
coefficient of R=0.576 in the ivacaftor group still suggests an
association, however this result is not statistically significant
(p=0.231).