Main findings:
This planned secondary analysis of the PITCHES trial showed that in
women with ICP, bile acid concentrations decreased after study enrolment
in both the UDCA and placebo groups. Baseline bile acid concentrations
did not affect a woman’s subsequent bile acid response to UDCA
treatment.
A small decrease in itch score was found in women taking UDCA with a
high baseline itch score, not seen in women with a low baseline itch
score. The decrease was statistically significant but judged too small
to be clinically meaningful for the majority of women and clinicians. As
the test of interaction did not show significance, targeting treatment
with UDCA for women with high baseline itch scores is not supported.
Further subgroup analyses evaluating baseline bile acid concentrations,
itch scores and initial bile acid trajectories found no group where an
effect of interaction was significant. This analysis therefore failed to
identify any subgroup that might respond favourably to UDCA. A poor
correlation was also demonstrated between bile acid concentrations and
itch scores.
The results of the repeated surveys demonstrate that for both women and
clinicians, their views on the size of a clinically meaningful reduction
in itch severity were unchanged from 2011. Women and clinicians
indicated that they deemed a median reduction in itch severity of 30 mm
(on a visual analogue scale with a mean baseline itch of 60 mm) as
clinically important.