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.