Design and validation of a histological scoring system for nonalcoholic fatty liver disease

HepatologyVolume 41, Issue 6 p. 1313-1321 Liver Failure and Liver DiseaseFree Access Design and validation of a histological scoring system for nonalcoholic fatty liver disease† David E. Kleiner, Corresponding Author David E. Kleiner KleinerD@mail.nih.gov Laboratory of Pathology, National Cancer Institute, Bethesda, MD fax: 301-480-9488Laboratory of Pathology, National Cancer Institute, Bldg 10, Room 2N212, MSC 1516, Bethesda, MD 20892===Search for more papers by this authorElizabeth M. Brunt, Elizabeth M. Brunt Saint Louis University Liver Center, Department of Pathology, Saint Louis University School of Medicine, St. Louis, MOSearch for more papers by this authorMark Van Natta, Mark Van Natta Johns Hopkins Center for Clinical Trials, Baltimore, MDSearch for more papers by this authorCynthia Behling, Cynthia Behling Department of Pathology, University of California San Diego, San Diego, CASearch for more papers by this authorMelissa J. Contos, Melissa J. Contos Department of Pathology, Virginia Commonwealth University, Richmond, VASearch for more papers by this authorOscar W. Cummings, Oscar W. Cummings Department of Pathology, University Hospital, Indianapolis, INSearch for more papers by this authorLinda D. Ferrell, Linda D. Ferrell Department of Pathology, University of California San Francisco, San Francisco, CASearch for more papers by this authorYao-Chang Liu, Yao-Chang Liu Department of Pathology, MetroHealth Medical Center, Cleveland, OHSearch for more papers by this authorMichael S. Torbenson, Michael S. Torbenson Department of Pathology, Johns Hopkins Hospital, Baltimore, MDSearch for more papers by this authorAynur Unalp-Arida, Aynur Unalp-Arida Johns Hopkins Center for Clinical Trials, Baltimore, MDSearch for more papers by this authorMatthew Yeh, Matthew Yeh Department of Pathology, University of Washington Medical Center, Seattle, WASearch for more papers by this authorArthur J. McCullough, Arthur J. McCullough Division of Gastroenterology, MetroHealth Medical Center, Cleveland, OHSearch for more papers by this authorArun J. Sanyal, Arun J. Sanyal Department of Internal Medicine, Division of Internal Medicine, Division of Gastroenterology, Virginia Commonwealth University Medical Center, Richmond, VASearch for more papers by this authorNonalcoholic Steatohepatitis Clinical Research Network, Nonalcoholic Steatohepatitis Clinical Research Network A list of members of the Nonalcoholic Steatohepatitis Clinical Research Network is located in the Appendix.Search for more papers by this author David E. Kleiner, Corresponding Author David E. Kleiner KleinerD@mail.nih.gov Laboratory of Pathology, National Cancer Institute, Bethesda, MD fax: 301-480-9488Laboratory of Pathology, National Cancer Institute, Bldg 10, Room 2N212, MSC 1516, Bethesda, MD 20892===Search for more papers by this authorElizabeth M. Brunt, Elizabeth M. Brunt Saint Louis University Liver Center, Department of Pathology, Saint Louis University School of Medicine, St. Louis, MOSearch for more papers by this authorMark Van Natta, Mark Van Natta Johns Hopkins Center for Clinical Trials, Baltimore, MDSearch for more papers by this authorCynthia Behling, Cynthia Behling Department of Pathology, University of California San Diego, San Diego, CASearch for more papers by this authorMelissa J. Contos, Melissa J. Contos Department of Pathology, Virginia Commonwealth University, Richmond, VASearch for more papers by this authorOscar W. Cummings, Oscar W. Cummings Department of Pathology, University Hospital, Indianapolis, INSearch for more papers by this authorLinda D. Ferrell, Linda D. Ferrell Department of Pathology, University of California San Francisco, San Francisco, CASearch for more papers by this authorYao-Chang Liu, Yao-Chang Liu Department of Pathology, MetroHealth Medical Center, Cleveland, OHSearch for more papers by this authorMichael S. Torbenson, Michael S. Torbenson Department of Pathology, Johns Hopkins Hospital, Baltimore, MDSearch for more papers by this authorAynur Unalp-Arida, Aynur Unalp-Arida Johns Hopkins Center for Clinical Trials, Baltimore, MDSearch for more papers by this authorMatthew Yeh, Matthew Yeh Department of Pathology, University of Washington Medical Center, Seattle, WASearch for more papers by this authorArthur J. McCullough, Arthur J. McCullough Division of Gastroenterology, MetroHealth Medical Center, Cleveland, OHSearch for more papers by this authorArun J. Sanyal, Arun J. Sanyal Department of Internal Medicine, Division of Internal Medicine, Division of Gastroenterology, Virginia Commonwealth University Medical Center, Richmond, VASearch for more papers by this authorNonalcoholic Steatohepatitis Clinical Research Network, Nonalcoholic Steatohepatitis Clinical Research Network A list of members of the Nonalcoholic Steatohepatitis Clinical Research Network is located in the Appendix.Search for more papers by this author First published: 24 May 2005 https://doi.org/10.1002/hep.20701Citations: 6,343 † Potential conflict of interest: Nothing to report. AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Abstract Nonalcoholic fatty liver disease (NAFLD) is characterized by hepatic steatosis in the absence of a history of significant alcohol use or other known liver disease. Nonalcoholic steatohepatitis (NASH) is the progressive form of NAFLD. The Pathology Committee of the NASH Clinical Research Network designed and validated a histological feature scoring system that addresses the full spectrum of lesions of NAFLD and proposed a NAFLD activity score (NAS) for use in clinical trials. The scoring system comprised 14 histological features, 4 of which were evaluated semi-quantitatively: steatosis (0-3), lobular inflammation (0-2), hepatocellular ballooning (0-2), and fibrosis (0-4). Another nine features were recorded as present or absent. An anonymized study set of 50 cases (32 from adult hepatology services, 18 from pediatric hepatology services) was assembled, coded, and circulated. For the validation study, agreement on scoring and a diagnostic categorization (“NASH,” “borderline,” or “not NASH”) were evaluated by using weighted kappa statistics. Inter-rater agreement on adult cases was: 0.84 for fibrosis, 0.79 for steatosis, 0.56 for injury, and 0.45 for lobular inflammation. Agreement on diagnostic category was 0.61. Using multiple logistic regression, five features were independently associated with the diagnosis of NASH in adult biopsies: steatosis (P = .009), hepatocellular ballooning (P = .0001), lobular inflammation (P = .0001), fibrosis (P = .0001), and the absence of lipogranulomas (P = .001). The proposed NAS is the unweighted sum of steatosis, lobular inflammation, and hepatocellular ballooning scores. In conclusion, we present a strong scoring system and NAS for NAFLD and NASH with reasonable inter-rater reproducibility that should be useful for studies of both adults and children with any degree of NAFLD. NAS of ≥5 correlated with a diagnosis of NASH, and biopsies with scores of less than 3 were diagnosed as “not NASH.” (HEPATOLOGY 2005;41:1313–1321.) Nonalcoholic fatty liver disease (NAFLD) is increasingly recognized as the hepatic manifestation of insulin resistance and the systemic complex known as metabolic syndrome.1-4 Prevalence estimates of NAFLD have used a variety of laboratory and imaging assessments and suggest that NAFLD may be the most common form of chronic liver disease in adults in the United States, Australia, Asia, and Europe, paralleling the “epidemic” of obesity in developed countries.5-9 Ludwig et al.10 are credited with solidifying the nomenclature and pathological findings of nonalcoholic steatohepatitis (NASH) in a seminal manuscript published in 1980. Now recognized as a progressive form of fatty liver disease, NASH has been documented to have the potential to progress to cirrhosis and hepatocellular carcinoma.3, 5 NASH may be a leading cause of “cryptogenic cirrhosis” in which etiologically specific clinical laboratory or pathological features can no longer be identified.11 NAFLD is also gaining recognition as a significant form of liver disease in pediatric populations, which in some patients may progress to cirrhosis in adulthood.12, 13 Whereas laboratory test abnormalities and radiographic findings may be suggestive of NAFLD, histological evaluation remains the only means of accurately assessing the degree of steatosis, the distinct necroinflammatory lesions and fibrosis of NASH, and distinguishing NASH from “simple” steatosis, or steatosis with inflammation.14 Matteoni et al.15 showed that cirrhosis developed in 21% to 28% of patients whose index biopsies had shown the combination of lesions of steatosis, inflammation, ballooning, and Mallory's hyaline or fibrosis, whereas only 4% of patients with simple steatosis and none of the patients with steatosis and inflammation alone had evidence of cirrhosis during the 10 years of follow-up. A system for semiquantitative evaluation for the unique lesions recognized for NASH proposed by Brunt et al.16 in 1999 was developed to parallel the concepts and terminology used in chronic hepatitis for semiquantitative evaluation, commonly referred to as “grading” and “staging.”17 The proposed system was based on the concept that the histological diagnosis of NASH rests on a constellation of features rather than any individual feature. However, it was developed for NASH and was not developed to encompass the entire spectrum of NAFLD as defined by Matteoni et al.15 A different semiquantitative feature-based scoring system for NAFLD was used in a recently published treatment trial from Promrat et al.18 Neither of these systems was designed to evaluate pediatric NAFLD, which may show different histological features than adult NASH.12 Beginning in 2002, the National Institute of Diabetes & Digestive & Kidney Diseases (NIDDK) sponsored the development of a multicenter cooperative Clinical Research Network for NASH.19 Among the goals of the network were: (1) to form a database for long-term natural history observations of patients with NAFLD; (2) to collect clinical samples for metabolic, immunological, molecular, and genetic studies of NAFLD focusing on defining the etiology of this disease; and (3) to evaluate promising therapies for NASH in both adult and pediatric populations. One of the charges to the NASH Clinical Research Network was to develop and validate a system of histological evaluation that would encompass the spectrum of NAFLD, that could be applied to pediatric NAFLD, and that would allow for assessment of changes with therapy. This report describes the multi-center effort to accomplish this task. Abbreviations NAFLD, nonalcoholic fatty liver disease; NASH, nonalcoholic steatohepatitis; NIDDK, National Institute of Diabetes & Digestive & Kidney Diseases; NIH, National Institutes of Health; H&E, hematoxylin and eosin; NAS, NAFLD activity score. Materials and Methods The Pathology Subcommittee, composed of pathologists from each Clinical Research Network Clinical Center (total of eight), a pathologist from the National Institutes of Health (NIH), two principal investigators from Clinical Centers, the NIDDK project scientist, and the principal investigator from the Data Coordinating Center, met to devise a scoring system and to discuss plans for case review. A study set was assembled from cases contributed by each center; the cases provided were drawn from locally evaluated patients who underwent biopsies to “rule out” NAFLD or NASH. Cases were specifically included to cover the range of possible diagnoses: (1) diagnostic of steatohepatitis, (2) borderline or possible steatohepatitis, and (3) not diagnostic of steatohepatitis. Each case had hematoxylin and eosin (H&E) and Masson trichrome stains submitted. The study set cases were stripped of all clinical information except for the designation as “adult” or “pediatric,” and the pathologists were blinded to even this piece of information. The Institute Review Boards at each Clinical Center, the Data Coordinating Center, and the Office of Human Subjects Research of the NIH approved the research plan. Scoring System Definition. The Committee reviewed the study set cases as a group and then proposed an evaluation method for each of the recognized features of NAFLD. The Committee agreed that only H&E and Masson's trichrome stains should be necessary to perform the evaluation. The histological features were grouped into five broad categories: steatosis, inflammation, hepatocellular injury, fibrosis, and miscellaneous features. The system of evaluation is detailed in Table 1, and examples of ballooning, microvesicular steatosis, and megamitochondria are shown in Figs. 1 and 2. Table 1. NASH Clinical Research Network Scoring System Definitions and Scores in Study Set Item Definition Score/Code % Responses in Category for Study Set Cases Adult (n = 576) Pediatric (n = 162) Steatosis Grade Low- to medium-power evaluation of parenchymal involvement by steatosis <5% 0 10% 3% 5%-33% 1 34% 29% >33%-66% 2 31% 31% >66% 3 26% 36% Location Predominant distribution pattern Zone 3 0 31% 14% Zone 1 1 1% 12% Azonal 2 37% 22% Panacinar 3 31% 52% Microvesicular steatosis** Ballooning classification: few indicates rare but definite ballooned hepatocytes as well as case that are diagnostically borderline; examples are shown in Fig. 1. Examples of patches of microvesicular steatosis and megamitochondria are shown in Fig. 2. Contiguous patches Not present 0 90% 96% Present 1 10% 4% Fibrosis Stage None 0 40% 29% Perisinusoidal or periportal 1 Mild, zone 3, perisinusoidal 1A 15% 4% Moderate, zone 3, perisinusoidal 1B 6% 5% Portal/periportal 1C 6% 27% Perisinusoidal and portal/periportal 2 12% 10% Bridging fibrosis 3 15% 17% Cirrhosis 4 6% 9% Inflammation Lobular inflammation Overall assessment of all inflammatory foci No foci 0 14% 15% <2 foci per 200× field 1 53% 60% 2-4 foci per 200× field 2 27% 22% >4 foci per 200× field 3 6% 3% Microgranulomas Small aggregates of macrophages Absent 0 57% 53% Present 1 43% 47% Large lipogranulomas Usually in portal areas or adjacent to central veins Absent 0 86% 99% Present 1 14% 1% Portal inflammation Assessed from low magnification None to minimal 0 67% 67% Greater than minimal 1 33% 33% Liver cell injury Ballooning** Ballooning classification: few indicates rare but definite ballooned hepatocytes as well as case that are diagnostically borderline; examples are shown in Fig. 1. Examples of patches of microvesicular steatosis and megamitochondria are shown in Fig. 2. None 0 33% 49% Few balloon cells 1 38% 36% Many cells/prominent ballooning 2 29% 15% Acidophil bodies None to rare†† The “None to rare” category is meant to alleviate the need for time-consuming searches for rare examples or deliberation over diagnostically borderline changes. If the feature is identified after a reasonable search, it should be coded as “many.” 0 89% 90% Many 1 11% 10% Pigmented macrophages None to rare†† The “None to rare” category is meant to alleviate the need for time-consuming searches for rare examples or deliberation over diagnostically borderline changes. If the feature is identified after a reasonable search, it should be coded as “many.” 0 87% 82% Many 1 13% 18% Megamitochondria** Ballooning classification: few indicates rare but definite ballooned hepatocytes as well as case that are diagnostically borderline; examples are shown in Fig. 1. Examples of patches of microvesicular steatosis and megamitochondria are shown in Fig. 2. None to rare†† The “None to rare” category is meant to alleviate the need for time-consuming searches for rare examples or deliberation over diagnostically borderline changes. If the feature is identified after a reasonable search, it should be coded as “many.” 0 86% 95% Many 1 14% 5% Other findings Mallory's hyaline Visible on routine stains None to rare†† The “None to rare” category is meant to alleviate the need for time-consuming searches for rare examples or deliberation over diagnostically borderline changes. If the feature is identified after a reasonable search, it should be coded as “many.” 0 80% 94% Many 1 20% 6% Glycogenated nuclei Contiguous patches None to rare†† The “None to rare” category is meant to alleviate the need for time-consuming searches for rare examples or deliberation over diagnostically borderline changes. If the feature is identified after a reasonable search, it should be coded as “many.” 0 57% 71% Many 1 43% 29% Diagnostic classification‡‡ Diagnostic classification was not available on 2 sets of adult biopsy observations, reducing the total of such observations to 512. Not steatohepatitis 0 31% 32% Possible/borderline 1 26% 33% Definite steatohepatitis 2 43% 35% * Ballooning classification: few indicates rare but definite ballooned hepatocytes as well as case that are diagnostically borderline; examples are shown in Fig. 1. Examples of patches of microvesicular steatosis and megamitochondria are shown in Fig. 2. † The “None to rare” category is meant to alleviate the need for time-consuming searches for rare examples or deliberation over diagnostically borderline changes. If the feature is identified after a reasonable search, it should be coded as “many.” ‡ Diagnostic classification was not available on 2 sets of adult biopsy observations, reducing the total of such observations to 512. Figure 1Open in figure viewerPowerPoint Scoring of ballooning injury. (A) There is mild steatosis but no ballooning degeneration. All pathologists scored this case as “0” for ballooning injury. (B) In no study set case was there absolute concordance among the nine pathologists for a ballooning score of 1. During the second round of reviews, this case was scored as 1+ ballooning injury by 8 of the 9 pathologists. This field shows several scattered balloon cells that are not much larger than the surrounding steatotic hepatocytes but with the same cytoplasmic characteristics as more obvious balloon cells, such as those seen in panel C. (C) This field is taken from a case scored as 2+ ballooning injury by all pathologists. There is a contiguous patch of hepatocytes showing prominent ballooning injury, sharply contrasted against the more normal hepatocytes in the field. (All photomicrographs: Hematoxylin and eosin; original magnification ×600). Figure 2Open in figure viewerPowerPoint Microvesicular steatosis and megamitochondria. (A) Contiguous patch of microvesicular steatosis from case of steatohepatitis. This case would be scored positively for this feature. (B) Photomicrograph of cells with easily identified megamitochondria (arrows). This case would be scored positively for this feature, although it is not necessary to see so many positive cells in a single field. (All photomicrographs: Hematoxylin and eosin; original magnification ×400). For the validation study, the pathologists were additionally asked to provide an overall diagnosis for each case as “NASH,” “borderline,” or “not NASH.” The biopsy specimens were made anonymous and randomized by an NIH employee not involved in the study. The adult cases were reviewed by each pathologist at his or her home institutions twice and at separate times; the pediatric cases were circulated once. Statistical Analyses. Pediatric and adult cases were analyzed separately. Weighted kappa scores were used to measure the degree of inter-rater and intra-rater agreement between and within multiple pathologists. Weighted kappa scores were estimated by using intra-class correlation coefficients derived from components of variance models.20 Chi-square tests were used to compare univariate associations of histological features with diagnosis of steatohepatitis. Multivariate associations with diagnosis of steatohepatitis were assessed by using multiple logistic regression models using generalized estimating equations with robust variance estimation and exchangeable correlation to account for correlations due to multiple readings within and between raters.21 Adjusted percentage distributions for each histological feature, holding other features constant and retaining the univariate marginal distributions, were calculated from the logistic regression model coefficients for comparison with the unadjusted univariate distributions of features. All statistical analyses were carried out by the Data Coordinating Center (M. Van N.) using SAS 8.0 (SAS Institute Inc., Cary, NC) and Stata 7.0 (Stata Corp., College Station, TX) Results A total of 50 anonymous liver biopsy specimens formed the validation study set. The study set was chosen to sample the range of pathological conditions seen in pediatric and adult NAFLD. The 32 cases from adults were each read twice by the nine pathologists, for a total of 576 sets of observations; the 18 pediatric cases were each read once, for a total of 162 sets of observations. Each possible score was used at least once during the course of the validation. The distribution of recorded scores is shown in Table 1. Analysis of agreement on features in the adult cases showed reasonable agreement on the scores for the major scoring categories of steatosis grade, fibrosis, ballooning injury, and Mallory's hyaline, with weighted kappa values for the adult study set of 0.5 and above (Table 2). Agreement was not as strong for the inflammatory changes or for steatosis location; both lobular and portal inflammation had interrater kappa values of 0.45. The interrater agreement on the diagnosis of steatohepatitis was 0.61. There was absolute agreement on the diagnosis between the nine pathologists on six cases and agreement among eight of the nine on a further five cases. The intra-rater agreement was higher in all categories than the interrater agreement. Table 2. Inter- and Intra-rater Variability Item Agreement (Kappa Score) Intra-rater Interrater Adult Cases (32 cases, 9 raters) Adult Cases (32 cases, 9 raters) Pediatric Cases (18 cases, 9 raters) Steatosis, grade 0.83 0.79 0.64 Steatosis, location 0.39 0.31 0.39 Microvesicular steatosis 0.37 0.34 0.02 Fibrosis 0.85 0.84 0.62 Lobular inflammation 0.60 0.45 0.28 Microgranulomas 0.40 0.18 0.15 Lipogranulomas 0.38 0.26 0.00 Portal inflammation 0.55 0.45 0.42 Ballooning 0.66 0.56 0.22 Acidophil bodies 0.28 0.19 0.27 Pigmented macrophages 0.38 0.15 0.06 Megamitochondria 0.28 0.16 −0.03 Mallory's hyaline 0.64 0.58 0.69 Glycogenated nuclei 0.66 0.58 0.32 Diagnostic classification 0.66 0.61 0.32 NOTE. All values represent weighted kappa statistics where appropriate. Feature scoring agreement on the pediatric cases in the study set was not as robust as in the adult study set, with lower weighted kappa scores in all categories except steatosis (0.64). Some of the results were statistically no better than chance (microvesicular steatosis, pigmented macrophages, lipogranulomas and megamitochondria, and glycogenated nuclei); this may be caused in part by the low level of agreement on the presence or absence of the feature as seen in the adult cases and in part by the low frequency of observation of one of the two scores. Many of the pediatric cases appeared to have more zone 1 steatosis, more “periportal only” fibrosis, less ballooning, and rare Mallory's hyaline. In particular, there was disagreement between pathologists on the diagnosis of steatohepatitis when cases had fibrosis and steatosis but little or no ballooning or lobular inflammation. Although it is accepted that steatohepatitis is a pattern of injury composed of several features, it has been difficult to define exact diagnostic criteria that all pathologists agree on to precisely distinguish NAFLD cases with steatohepatitis from those with only steatosis and inflammation.14 Data generated by the NASH Network study on how each pathologist categorized each case along with the assigned feature scores allowed statistical examination of which individual features were useful in discriminating definite steatohepatitis from the other two categories. Both crude and adjusted analyses were performed to address these questions; the results are shown in Table 3. Several features showed significant association with the diagnosis of steatohepatitis on both analyses and for both adults and children, including lobular inflammation, ballooning degeneration, and fibrosis. In the adult cases, the degree of steatosis showed a trend toward significance in the crude analysis but was clearly associated with the diagnosis of NASH in the adjusted analysis. In children, the degree of steatosis above the 5% cutoff was not associated with the diagnosis of NASH in either analysis. Table 3. Logistic Regression Analysis of Features of NAFLD With Respect to the Diagnosis of NASH Histologic Feature of NAFLD Category Percent With Diagnosis of NASH Adult (n = 512 Readings From 32 Biopsies) Pediatric (n = 162 Readings From 18 Biopsies) No Adjustment Adjusted** Adjusted percent with NASH diagnosis calculated from a logistic regression model for correlated data with NASH diagnosis as the outcome and indicator variables for each histological feature. Marginal totals for adjusted percentages were fixed to equal the unadjusted marginal totals, and odds ratios from the adjusted percentages equal those from the logistic regression model. No Adjustment Adjusted** Adjusted percent with NASH diagnosis calculated from a logistic regression model for correlated data with NASH diagnosis as the outcome and indicator variables for each histological feature. Marginal totals for adjusted percentages were fixed to equal the unadjusted marginal totals, and odds ratios from the adjusted percentages equal those from the logistic regression model. Overall diagnosis of NASH (outcome) 43.1% 43.1% 34.6% 34.6% Steatosis Grade <5% 12.5% 5.8% †† Combined 5 observations in the <5% category with 5%-33% category because there were no events in the <5% category. †† Combined 5 observations in the <5% category with 5%-33% category because there were no events in the <5% category. 5%-33% 35.2% 37.3% 21.3% 35.2% >33%-66% 52.8% 46.2% 45.1% 32.9% >66% 51.8% 59.2% 39.0% 35.5% P value‡‡ P values were derived from comparisons of percentages with diagnosis of NASH across categories of each histological feature and were calculated from chi-square tests (unadjusted percentages) or from Wald's tests from the logistic regression model (adjusted percentages). .08 .009 .11 .98 Location Zone 3 45.7% 49.2% 27.3% 16.7% Zone 1 25.0% 20.8% 5.0% 18.5% Azonal 31.6% 36.6% 38.9% 28.5% Panacinar 54.6% 45.6% 41.7% 45.7% P value .01 .61 .17 .46 Microvesicular steatosis Absent 43.2% 44.8% 35.3% 35.3% Present 41.9% 24.6% 16.7% 15.5% P value .60 .28 .44 .39 Fibrosis stage None 10.1% 16.3% 14.9% 13.2% Mild, zone 3 53.3% 61.4% 66.7% 71.6% Moderate, zone 3 93.3% 97.7% 87.5% 99.1% Portal/periportal 11.1% 9.0% 13.6% 16.7% Zone 3 & periportal 76.6% 74.2% 43.8% 48.9% Bridging 83.6% 64.4% 70.4% 72.6% Cirrhosis 54.6% 42.1% 42.9% 20.1% P value <.0001 <.0001 <.0001 .0001 Inflammation Lobular inflammation No foci 1.2% 1.1% 12.0% 4.7% <2 foci 36.0% 38.0% 36.1% 32.5% 2-4 foci 76.6% 73.3% 42.9% 53.2% >4 foci 87.5% 82.1% 60.0% 93.7% P value <.0001 <.0001 .02 .01 Microgranulomas Absent 42.6% 36.1% 39.5% 38.2% Present 43.9% 51.8% 29.0% 30.4% P