Quantification of Liver Fat Content: Diagnostic Evaluation of Proton Magnetic Resonance Spectroscopy Compared with Histological Methods

POSTER PRESENTATIONS to a healthy liver were observed. Only in patients with high fibrosis or cirrhosis the test did not perform well, due to the resemblance of the metabolic profile of these patients to those with a normal liver. Conclusions: The OWLiver test is able to non-invasively discriminate between steatosis and NASH, using just a serum sample and avoiding a liver biopsy. The test is less accurate in extreme cases, such as patients with a high amount of fibrosis or cirrhosis. The test emerges as a highly useful tool for specialists to identify those patients with steatosis or normal liver and direct them to primary care, allowing the specialist to focus on patients either with NASH or at risk of developing this more severe condition. FRI-324 PNPLA3 VARIANTS CONFER AN INCREASED RISK OF ADVANCED FIBROSIS DUE TO NON-ALCOHOLIC STEATOHEPATITIS P.R. Shea1, A. Sanyal2, S. Harrison3, V. Ratziu4, R. Loomba5, S. Caldwell6, A.M. Diehl7, S.E. Kleinstein7, R.P. Myers8, G. Mani Subramanian8, J.G. McHutchison8, M.F. Abdelmalek7, J. Bosch9, N. Afdhal10, D.B. Goldstein1. 1Institute for Genomic Medicine, Columbia University, New York; 2Virginia Commonwealth University, Richmond; 3San Antonio Military Medical Center, Fort Sam Houston, United States; 4 Hôpital Pitié-Salpêtrier̀ e, Paris, France; 5University of California San Diego, San Diego; 6University of Virginia, Charlottesville; 7Duke University School of Medicine, Durham; 8Gilead Sciences, Inc., Foster City, United States; 9University of Barcelona, Barcelona, Spain; 10 Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, United States E-mail: [email protected] Background and Aims: Genetic variants in patatin like phospholipase-3 (PNPLA3) have been associated with hepatic steatosis in the general population, and the severity of nonalcoholic steatohepatitis (NASH) and fibrosis in patients with nonalcoholic fatty liver disease. Our objective was to validate these findings in a cohort of patients with advanced fibrosis due to NASH. Methods: We genotyped patients with NASH and bridging fibrosis (Ishak stage 3 or 4) or cirrhosis (stage 5 or 6) enrolled in two phase 2b trials of simtuzumab, a monoclonal antibody directed against lysyl oxidase-like-2 (LOXL2). Genotyping was performed at over 5 million single nucleotide polymorphism (SNP) loci using the Illumina Omni5 high density BeadArray chip. For this analysis, we focused on the rs738409 SNP in PNPLA3. The frequency of the risk allele (G) at rs738409 in the NASH cohort was compared with that observed in 4,488 Caucasian population controls. In addition, a GWAS was conducted comparing the NASH cohort to 198 patients with primary sclerosing cholangitis (PSC) who were enrolled in a separate phase 2b trial of simtuzumab. Results: 406 of 477 randomized and treated NASH patients (85%) provided informed consent for genetic analysis. The median age was 56 years, 37% were male, 91% were Caucasian, and 54% had cirrhosis. The frequency of the G allele at rs738409 in PNPLA3 in the pooled NASH cohort (50.7%) was significantly higher than in the population controls (23%; odds ratio [OR] 3.41; p = 2.77 × 10−52). In stratified analyses according to the severity of fibrosis, the G allele was more frequent in NASH patients with bridging fibrosis (45%; OR 2.73; p = 8.36 × 10−18 vs. controls) and cirrhosis (55.5%; OR 4.13; p = 3.08 × 10−40 vs. controls and p = 3.81 × 10−4 vs. bridging fibrosis). In the NASH vs. PSC GWAS, rs738409 at PNPLA3 was the most highly differentiating SNP (G allele frequency in PSC, 21%; p = 2.50 × 10−9). Three additional SNPs, all in the PNPLA3 gene, also exceeded the genome-wide threshold for statistical significance (rs738408 [p = 3.15 × 10−9], rs3747207 [p = 4.21 × 10−9], and rs2294915 [p = 1.67 × 10−8]). Conclusions: Genetic variation at PNPLA3 confers an increased risk of advanced fibrosis due to NASH.

FRI-325 QUANTIFICATION OF LIVER FAT CONTENT: DIAGNOSTIC EVALUATION OF PROTON MAGNETIC RESONANCE SPECTROSCOPY COMPARED WITH HISTOLOGICAL METHODS P. Nasr1, M.F. Forsgren1, S. Ignatova2, O.D. Leinhard1, N. Dahlström1, M. Ekstedt1, P. Lundberg1, S. Kechagias1. 1Department of Medical and Health Sciences; 2Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden E-mail: [email protected] Background and Aims: Hepatic steatosis is the most common manifestation of liver disease in the Western world. Non-targeted liver biopsy with semi-quantitative histological steatosis grading has been the reference standard for the diagnosis and grading of hepatic steatosis. Proton magnetic resonance spectroscopy (1H-MRS) noninvasively measures hepatic total lipid load and has been suggested to replace liver biopsy for the assessment of liver fat content. We performed a diagnostic evaluation of 1H-MRS compared with semiquantitative histological steatosis grading and quantitative histological steatosis measurement. Methods: Subjects referred for evaluation of elevated liver function tests were included. A diagnostic work-up was performed including physical examination, laboratory investigation, and 1H-MRS immediately followed by liver biopsy. Histological semiquantitative grading of steatosis was performed using Brunt criteria and quantitative assessment of fat in biopsies was performed by measuring the area of the section involved with steatosis using stereological point counting (SPC). Results: The study was conducted in 94 subjects, of whom 37 had NAFLD, 49 had other chronic liver diseases, and 8 had normal liver biopsy. A very strong correlation was observed between 1H-MRS and SPC (rc = 0.88, p < 0.0001; к = 0.82). Only fair correlation was observed between 1H-MRS and semi-quantitative histological quantification (к = 0.26) and between SPC and semi-quantitative histological quantification (к = 0.38). Considering Brunt criteria gold standard for diagnosing hepatic steatosis, at a cut-off value > 5% for hepatic triglyceride content (HTGC) measured with 1H-MRS all subjects had steatosis (specificity 100%). Of 69 patients with HTGC ≤ 5% quantified with 1H-MRS 22 were diagnosed with steatosis according to Brunt criteria (sensitivity 53%). Reducing the cut-off value to 2% increased sensitivity to 87% maintaining a high specificity (94%). The corresponding figures for specificity and sensitivity at a cut-off value of 1.36% for HTGC measured with 1H-MRS were 89% and 98%, respectively. Conclusions: 1H-MRS and SPC show an excellent correlation for quantifying hepatic steatosis. SPC should therefore be used when accurate histological quantification of liver fat is desired. Many subjects may have hepatic steatosis according to Brunt criteria despite HTGC ≤5% quantified with 1H-MRS. A reduced cut-off value for diagnosing steatosis with 1H-MRS is plausible. FRI-326 A SYSTEMATIC REVIEW ON NON-INVASIVE DIAGNOSTIC METHODS FOR NON-ALCOHOLIC STEATOHEPATITIS: A META-ANALYSIS P. Verhaegh1, R. Bavalia1, B. Winkens2, A. Masclee1, D. Jonkers1, G. Koek1. 1Division of Gastroenterology-Hepatology, Department of Internal Medicine, Maastricht University Medical Center; 2Department of Methodology and Statistics, Maastricht University, Maastricht, Netherlands E-mail: [email protected] Background and Aims: Non-alcoholic fatty liver disease (NAFLD) is a rapidly increasing health problem in Western society. NAFLD may progress towards fibrosis, cirrhosis and hepatocellular carcinoma. At present, liver biopsy is the most sensitive test for staging NAFLD and to differentiate non-alcoholic steatohepatitis (NASH) from simple steatosis (SS). Due to the invasive character and side effects, it is not

Journal of Hepatology 2016 vol. 64 | S425–S630

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