Maternal outcomes:
Bile acid concentrations and itch scores post-randomisation, stratified
by baseline characteristics, are shown in Table 1.
Mean trajectories of bile acid concentration grouped by baseline bile
acid concentration are shown in Figure 1. Visual inspection shows that
bile acid concentrations reduced in women taking UDCA and placebo, most
notable in women with baseline bile acid concentrations ≥40 μmol/L, and
also seen in women with baseline bile acid concentrations ≥100 μmol/L.
In women with baseline bile acid concentrations <40 μmol/L,
treatment with UDCA resulted in higher post-randomisation bile acid
concentrations compared to placebo (geometric mean ratio 1.19, 95% CI
1.00 to 1.41, p = 0.047). There was no significant increase in women
with higher baseline bile acid concentrations (≥40 μmol/L) (geometric
mean ratio 1.13, 95% CI 0.81 to 1.58, p = 0.466). A test of interaction
showed no significance (p = 0.647). When stratified by a higher
threshold (100 μmol/L), in women with baseline bile acid concentrations
<100 μmol/L, treatment with UDCA resulted in increased
post-randomisation bile acid concentrations (geometric mean ratio 1.19,
95% CI 1.02 to 1.39, p = 0.031). There was no significant difference in
women with baseline bile acid concentrations ≥100 μmol/L (geometric mean
ratio 0.97, 95% CI 0.48 to 1.96, p = 0.941). A test of interaction
showed no significance (p = 0.458).
Mean trajectories of itch score stratified by baseline itch score and
baseline bile acid concentration are shown in Figure 2. In women with a
high baseline itch score (≥60 mm), treatment with UDCA resulted in a
small 6.0 mm decrease in itch score compared to placebo (p = 0.041).
There was no evidence of a significant effect of UDCA seen in women with
a baseline itch score <60 mm. A test of interaction showed no
significance (p = 0.640). There was no difference in change in itch
score between women with a high or low baseline bile acid concentration
and a test of interaction showed no significance (p = 0.455). Similarly,
a test of interaction showed no significance (p = 0.753) in women
stratified by a baseline bile acid concentration threshold of 100
μmol/L.
Mean trajectories of bile acid concentration and itch score were further
examined, stratified by initial bile acid trajectory either increasing
or decreasing, as shown in Figures S2 and S3. Tests of interaction
showed no significance for moderation of either post-randomisation bile
acid concentrations or post-randomisation itch score.
The relationship between itch score and bile acid concentration for all
women at all visits is shown in Figure 3. The adjusted
R2 was 0.080.