Cheung, Angela C

The United Kingdom‐Primary Biliary Cholangitis (UK‐PBC) risk scores are a set of prognostic models that estimate the risk of end‐stage liver disease in patients with PBC at 5‐, 10‐ and 15‐year intervals. They have not been externally validated outside the United Kingdom. In this retrospective, external validation study, data were abstracted from outpatient charts and discrimination and calibration of the UK‐PBC risk scores were assessed. A total of 464 patients with PBC treated with ursodeoxycholic acid were included. The median diagnosis age was 52.4 years, and 88% were female patients. The cumulative incidence of events was 6%, 9%, and 15% at 5, 10, and 15 years, respectively. Concordance (c‐statistic) was 0.88, 0.85, and 0.84 using the 5‐, 10‐ and 15‐year risk scores, respectively, which was slightly lower than values observed in the United Kingdom validation cohort. Using the 5‐year risk score, more events were observed than predicted (25 versus 16.8; P = 0.046); using the 10‐year risk score, there was no difference between the observed and predicted number of events (35 versus 44.9; P = 0.14); conversely, using the 15‐year risk score, fewer events were observed than predicted (46 versus 67.5; P = 0.009). Limiting evaluation by the 15‐year UK‐PBC risk score to those with >10 years of follow‐up demonstrated no difference between observed and predicted events. Using the 5‐year risk score, patients within the highest quartile had statistically significant worse event‐free survival compared to the rest of the cohort: 82% versus 98% at 5 years, 73% versus 97% at 10 years, and 58% versus 93% at 15 years. Conclusion: In patients assessed at a North American tertiary medical center, the UK‐PBC risk score had excellent discrimination and was reasonably calibrated both in the short and long term. (Hepatology Communications 2018;2:676‐682)

AbstractEpigenomics, the study of modifications to genetic material that do not alter the underlying DNA sequence, is generating increasing interest as a means to help clarify disease pathogenesis and outcomes. Although genome-wide association studies have identified several potential candidate genes that may be implicated in primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC), it is estimated that these genes explain less than 20% of the heritability of these diseases. Thus, to date, the origins of “missing heritability” for PBC and PSC remain elusive. The epigenome may provide a potentially elegant solution to this phenomenon, as it can be modified by both internal and external exposures (coined the “exposome”). This may explain differences in disease presentation, treatment response, and rates of progression between individuals. Epigenetic changes may also provide a framework for discovering potential biomarkers for diagnosis and screening of PBC and PSC. Importantly, because the epigenome is modifiable, it may also highlight novel pathways for therapeutic discovery and interventions of these diseases.