Copyright © 2015 Wolters Kluwer Health, Inc. Unauthorized reproduction of the article is prohibited. Longer duration of transient elastography predicts unreliable liver stiffness measurements Ken Liu a,b , Kim Tam Bui a , Crispin Corte a,b , Alice Lee a , Meng Chong Ngu a,b and Venessa Pattullo a,b Background Transient elastography (TE) is a noninvasive, validated method to assess liver fibrosis by obtaining liver stiffness measurements (LSM). However, TE can be limited by unreliable measurement (UM). The relationship between the time taken to perform TE (duration) and UM has not been studied. Objectives To determine whether the duration of TE correlates with UM. Materials and methods We prospectively studied the frequency and predictors of UM over a 5-year period. UM was defined as follows: less than 10 successful measurements, success rate less than 60%, or interquartile range more than 30% of the median LSM value (IQR/LSM > 30%). Results Among the 2834 patients with LSM analysed, UM occurred in 19.0%. Duration [odds ratio (OR) 4.2, 95% confidence interval (CI) 2.8–6.4; P < 0.0001] was the strongest predictor of UM, followed by BMI more than 28 kg/m 2 (OR 2.1, 95% CI 1.5–3.0; P < 0.0001), age more than 52 (OR 1.6, 95% CI 1.1–2.3; P = 0.007) and non-HBV aetiology (OR 1.6, 95% CI 1.1–2.3; P = 0.02). An optimal cut-off of 3 min 47 s was calculated for predicting UM (sensitivity 70%, specificity 65%, OR 4.2, 95% CI 2.7–6.6, P < 0.0001). Examinations that took longer than 8 min 10 s had a 90% chance of UM. Conclusion In experienced hands, duration is a strong predictor of UM in patients undergoing TE. Examinations longer than 4 min are more likely to be unreliable. Examinations longer than 8 min are unlikely to yield a valid result and should be considered a futility endpoint. Older age and increased BMI and nonhepatitis B aetiology are independent, albeit weaker, predictors of UM. Eur J Gastroenterol Hepatol 27:655–659 Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved. Introduction In patients with chronic liver disease, assessment of liver fibrosis severity is an important factor in predicting prog- nosis and guiding therapeutic decisions. Liver biopsy has long been considered the gold standard for assessing liver fibrosis. However, liver biopsy is inva- sive and therefore has the associated risk of complications. Sampling error, interobserver variation and the require- ment for adequate biopsy size without fragmentation limit the utility of histopathological examination of tissue obtained by the ‘gold standard’ [1–4]. Transient elastography (TE) is a noninvasive method to assess liver fibrosis by obtaining liver stiffness measure- ments (LSM). It has been validated in patients across various liver diseases and is excellent for the diagnosis of severe fibrosis and cirrhosis [5,6]. However, reliable LSM cannot be obtained in all cases. Measurement failure (MF) and unreliable measurement (UM) occur in up to 5 and 15% of patients, respectively [7–9]. Several factors have been identified to be associated with MF and UM includ- ing high BMI, central obesity, older age, female sex and operator inexperience [7,9]. To our knowledge, the relationship between the time taken to perform TE (duration) and UM has not been studied previously. The aim of this study was to determine whether the examination duration correlates with UM of TE. Materials and methods Study population In this prospective study, all TE examinations performed on adults with suspected liver disease from September 2008 to June 2013 were included. Patients with ascites (either clinically evident or documented by previous ima- ging) were excluded from the study. The study protocol was approved by the Sydney Local Health District Human Research Ethics Committee. Data collected included age, sex, BMI, probe used (M or XL), stiffness (LSM in kPa), duration of TE (in min : s) and aetiology of liver disease. Viral hepatitis B (HBV) and C (HCV) were diagnosed by positive serology for serum hepatitis B surface antigen and HCV antibodies, respec- tively. Nonalcoholic fatty liver disease (NAFLD) was diagnosed by ultrasonography and/or histology after exclusion of other possible aetiologies of fatty liver [10]. Autoimmune and cholestatic liver diseases (primary biliary cirrhosis and primary sclerosing cholangitis) were diag- nosed on the basis of standard serological, cholangio- graphy and histological criteria. a Department of Gastroenterology, Concord Hospital, Concord and b Faculty of Medicine, University of Sydney, Sydney, Australia Correspondence to Venessa Pattullo, MBBS, FRACP, PhD, Department of Gastroenterology, Level 1 West, Concord Hospital, Hospital Rd., Concord, NSW 2139, Australia Tel: + 61 297 676 111; fax: + 61 297 676 767; e-mail: venessa.pattullo@sydney.edu.au Received 8 December 2014 Accepted 14 January 2015 European Journal of Gastroenterology & Hepatology 2015, 27:655–659 Keywords: duration, Fibroscan, hepatitis B, hepatitis C, liver stiffness, measurement failure, transient elastography, unreliable measurement ’ Original article 0954-691X Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved. DOI: 10.1097/MEG.0000000000000310 655