Objectives: Pruritus can be a debilitating symptom for patients with progressive familial intrahepatic cholestasis (PFIC), a disease that commonly presents in young children. In the phase 3 PEDFIC 1 study (NCT03566238), odevixibat, an ileal bile acid transporter inhibitor, reduced pruritus compared with placebo based on caregiver report in children with PFIC using the PRUCISION scale. Patient-reported pruritus data were also collected from patients aged ≥8 years. This analysis examines the correlation between patient- and caregiver-reported pruritus scores in PEDFIC 1.

Methods: Randomized patients in PEDFIC 1 (N=62) received once-daily placebo or odevixibat (40 or 120 µg/kg) over 6 months. Pruritus was assessed as a patient-reported outcome (PRO) or observer (caregiver)-reported outcome (ObsRO) using the PRUCISION scale (range: 0–4; higher scores indicate worse symptoms). A blinded analysis of PEDFIC 1 data found a 1.0-point decrease from baseline in ObsRO score to be clinically meaningful. Here, Pearson correlations were used to assess relationships between PRO and ObsRO pruritus scores at baseline (14-day average pruritus scores) and during treatment (28-day average pruritus scores).

Results: In total, 10 patients (mean age, 11.7 years; 60% female) with PFIC1 (n=2) or PFIC2 (n=8) met age criteria for completing the PRO, although 1 eligible patient was unable to complete this measure due to disability. Caregivers of all patients completed the ObsRO. At baseline, mean (median) pruritus score (2.8 [3.0]) for the 9 patients who completed the PRO was similar to that of their caregivers (mean [median] ObsRO score, 2.8 [2.9]); these were strongly correlated (r=0.97, P<0.0001) and remained strongly correlated over time from months 1 to 6 (all: r≥0.96 and P≤0.0001).

Conclusion: PRO pruritus scores significantly correlated with ObsRO pruritus scores at all time points in PEDFIC 1, highlighting the consistency between the PRUCISION instruments for measuring pruritus severity in patients with PFIC.