ORIGINAL ARTICLE The interpretation of hepatic venous pressure gradient tracings – excellent interobserver agreement unrelated to experience Puneeta Tandon 1,2 , Cristina Ripoll 1,3 , David Assis 1 , Suchat Wongcharatrawee 1 , Roberto J. Groszmann 1 and Guadalupe Garcia-Tsao 1 1 Section of Digestive Diseases, Yale University School of Medicine, New Haven, CT, USA 2 Cirrhosis Care Clinic, University of Alberta, Edmonton, AB, Canada 3 First Department of Internal Medicine, Martin Luther University, Halle-Wittenberg, Halle, Germany DOI: 10.1111/liv.13065 Abstract Background and Aims: The hepatic venous pressure gradient (HVPG) plays an important role in the diagnosis, prognosis and therapy of patients with cirrhosis and portal hypertension. One barrier to its widespread use is the potential for a low reproducibility. We aimed to evaluate the interobserver agreement in the interpretation of optimally acquired HVPG tracings from patients with cirrhosis and different degrees of portal hypertension. Methods: Two hundred and fifteen tracings obtained from 51 patients with cirrhosis in a single centre were interpreted independently by two hepatologists: one experi- enced observer and one inexperienced observer. Correlation was performed by Pearson linear regression and the intraclass correlation coefficient (ICC). A Bland–Altman plot was constructed to visualize how the differences between observers com- pared across the range of measurements. Logistic regression was used to identify predictors of ≥10% variation between observers’ readings. Results: There was a significant linear relationship between observers’ readings r = 0.98 (P = 0.001). The ICC between observers (interobserver agreement) was also excellent at 0.991 (P = 0.001). Using the Bland–Altman technique, the mean difference between the observers’ readings was 0.2 mmHg (95% CI: 1.2 mmHg to 1.6 mmHg). Thir- teen per cent of all readings and 9% of readings with an HVPG of ≥10 mmHg differed by ≥10%. As expected, a lower base- line HVPG was a predictor of this variability. Conclusions: Interobserver reproducibility in the assessment of optimally acquired HVPG tracings is excellent without differences related to experience. The data provide further support that the HVPG can be used accurately in clinical and research settings. Keywords hepatic venous pressure gradient – interobserver reliability – portal pressure – portal pressure measurement The preferred, albeit indirect, method for assessing por- tal pressure is the wedged hepatic venous pressure (WHVP), measurement that is obtained by placing a catheter in the hepatic vein and wedging it into a small branch or, better still, by inflating a balloon and occlud- ing a larger branch of the hepatic vein (1). The WHVP has been shown to correlate very closely with direct measurements of portal pressure both in alcoholic and non-alcoholic cirrhosis (2–5). The WHVP is always cor- rected for increases in intra-abdominal pressure (e.g. ascites) by subtracting the free hepatic vein pressure (FHVP) or the intra-abdominal inferior vena cava Abbreviations ANOVA, analysis of variance; FHVP, free hepatic venous pressure; HVPG, hepatic venous pressure gradient; ICC, intraclass correlation coefficient; IQR, interquartile range; WHVP, wedged hepatic venous pressure. Correspondence Dr Guadalupe Garcia-Tsao, Department of Internal Medicine, Digestive Diseases, Yale University School of Medicine, One Gilbert Street, TAC, Room No. S241B, New Haven, CT 06510, USA Tel: +1 203 737 6063; Fax: +1 203 785 7273 e-mail: guadalupe.garcia-tsao@yale.edu Handling Editor: Christophe Bureau Received 3 August 2015; Accepted 31 December 2015 Additional Supporting Information may be found at onlinelibrary.wiley.com/doi/10.1111/liv.13065/suppinfo Liver International (2016) © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd 1 Liver International ISSN 1478-3223