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Hepatology
Original article
A novel prognostic model for transplant-free survival in primary sclerosing cholangitis
  1. Elisabeth M de Vries1,
  2. Junfeng Wang2,
  3. Kate D Williamson3,4,
  4. Mariska M Leeflang2,
  5. Kirsten Boonstra1,
  6. Rinse K Weersma5,
  7. Ulrich Beuers1,
  8. Roger W Chapman3,4,
  9. Ronald B Geskus2,3,6,
  10. Cyriel Y Ponsioen1
  1. 1 Department of Gastroenterology & Hepatology, Academic Medical Center, Amsterdam, The Netherlands
  2. 2 Department of Clinical Epidemiology, Biostatistics and Bioinformatics, Amsterdam Public Health Research Institute, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
  3. 3 Nuffield Department of Medicine, University of Oxford, Oxford, UK
  4. 4 Translational Gastroenterology Unit, John Radcliffe Hospital, Oxford, Oxfordshire, UK
  5. 5 Department of Gastroenterology and Hepatology, University Medical Center Groningen, Groningen, The Netherlands
  6. 6 Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
  1. Correspondence to Dr Cyriel Y Ponsioen, Department of Gastroenterology and Hepatology Academic Medical Center Meibergdreef 9,1105 AZ, Amsterdam, The Netherlands ; c.y.ponsioen{at}amc.uva.nl

Abstract

Objective Most prognostic models for primary sclerosing cholangitis (PSC) are based on patients referred to tertiary care and may not be applicable for the majority of patients with PSC. The aim of this study was to construct and externally validate a novel, broadly applicable prognostic model for transplant-free survival in PSC, based on a large, predominantly population-based cohort using readily available variables.

Design The derivation cohort consisted of 692 patients with PSC from the Netherlands, the validation cohort of 264 patients with PSC from the UK. Retrospectively, clinical and biochemical variables were collected. We derived the prognostic index from a multivariable Cox regression model in which predictors were selected and parameters were estimated using the least absolute shrinkage and selection operator. The composite end point of PSC-related death and liver transplantation was used. To quantify the models’ predictive value, we calculated the C-statistic as discrimination index and established its calibration accuracy by comparing predicted curves with Kaplan-Meier estimates.

Results The final model included the variables: PSC subtype, age at PSC diagnosis, albumin, platelets, aspartate aminotransferase, alkaline phosphatase and bilirubin. The C-statistic was 0.68 (95% CI 0.51 to 0.85). Calibration was satisfactory. The model was robust in the sense that the C-statistic did not change when prediction was based on biochemical variables collected at follow-up.

Conclusion The Amsterdam-Oxford model for PSC showed adequate performance in estimating PSC-related death and/or liver transplant in a predominantly population-based setting. The transplant-free survival probability can be recalculated when updated biochemical values are available.

  • Primary Sclerosing Cholangitis

This is an open access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) license, which permits others to distribute, remix, adapt and build upon this work, for commercial use, provided the original work is properly cited. See: http://creativecommons.org/licenses/by/4.0/

https://doi.org/10.1136/gutjnl-2016-313681

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    Footnotes

    • EMV and JW contributed equally.

    • RBG and CYP contributed equally.

    • Contributors CYP designed the study and supervised the project. EMdV collected data of patients with PSC included in the derivation data set, interpreted the data and prepared the first draft of the manuscript. JW performed the statistical analyses and interpretation of data, prepared the figures and the results section of the manuscript. RBG and MML supervised the statistical analyses and interpretation of data. KB and RKW identified patients with PSC included in the derivation data set, and collected patient data. RWC identified patients with PSC included in the validation data set. KDW provided clinical and biochemical data of patients with PSC included in the validation data set. All authors reviewed the manuscript for critical content and approved the final version.

    • Funding KW is supported by a grant from the Welomce Trust (200154/Z/15/Z)

    • Competing interests None declared.

    • Patient consent obtained.

    • Ethics approval The central Committee for Research Ethics in Utrecht and all local ethics committees of the participating hospitals in the Netherlands (trialregister.nl number, NTR2813).

    • Provenance and peer review Not commissioned; externally peer reviewed.