A validated clinical tool for the prediction of varices in PBC: the Newcastle Varices in PBC Score

Abstract

Background & aims: Gastro-oesophageal varices (GOV) can occur in early stage primary biliary cirrhosis (PBC), making it difficult to identify the appropriate time to begin screening with oesophageo-gastro-duodenoscopy (OGD). Our aim was to develop and validate a clinical tool to predict the probability of finding GOV in PBC patients.

Methods: A cross-sectional retrospective study analysing clinical data of 330 PBC patients who underwent an OGD at the Freeman Hospital, Newcastle was used to create a predictive tool, the Newcastle Varices in PBC (NVP) Score, that was externally validated in PBC patients from Cambridge (UK) and Toronto (Canada).

Results: 48% of the Newcastle, 31% of the Cambridge, and 22% of the Toronto cohorts of PBC patients had GOV. Twenty-five percent (95% CI 18-32%) of the Newcastle cohort had GOV diagnosed at an index variceal bleed. Of the others, 37% (95% CI 28-46%) bled after a median of 1.5 years (IQR 3.75). Transplant-free survival was significantly better in those without GOV than in those with GOV (p<0.001), but similar in patients with GOV that bled and those that did not (p=0.1). The NVP score (%Probability)=1/[1+exp^-(9.186+0.001*alkaline phosphatase in IU-0.178*albumin in g/L-0.015*platelet × 10(9)) was validated in 2 external cohorts and was highly discriminant (AUROC 0.86). Cost consequences analyses revealed the NVP score to be as accurate as, but more economical than using either OGD directly or other risk scores for screening PBC patients.

Conclusions: The NVP score is an inexpensive, non-invasive, externally validated tool that accurately predicts GOV in PBC.

Keywords: ALP; ALT; AUROC; Bil; CI; Chronic; GOV; Health economics; IQR; Liver disease; MABPT; Males Albumin<3.5 g/dl Bilirubin >1.2 mg/dl &/or PT > 12.9s; NVP score; Newcastle Varices in PBC Score; OGD; PBC; PT; Portal hypertension; ROC; UDCA; alanine aminotransferase; alkaline phosphatase; area under the receiver operating characteristic curve; bilirubin; confidence interval; gastro-oesophageal varices; interquartile range; oesophageo-gastro-duodenoscopy; primary biliary cirrhosis; prothrombin time; receiver operating characteristic curve; ursodeoxycholic acid.