Validation of the accuracy of the FAST™ score for detecting patients with at-risk nonalcoholic steatohepatitis (NASH) in a North American cohort and comparison to other non-invasive algorithms.

BACKGROUND AND AIMS: Management of patients with NASH who are at elevated risk of progressing to complications of cirrhosis (at-risk NASH) would be enhanced by an accurate, noninvasive diagnostic test. The new FAST™ score, a combination of FibroScan® parameters liver stiffness measurement (LSM) and controlled attenuation parameter (CAP) and aspartate aminotransferase (AST), has shown good diagnostic accuracy for at-risk NASH (area-under-the-Receiver-Operating-Characteristic [AUROC] = 0.80) in European cohorts. We aimed to validate the FAST™ score in a North American cohort and show how its diagnostic accuracy might vary by patient mix. We also compared the diagnostic performance of FAST™ to other non-invasive algorithms for the diagnosis of at-risk NASH. METHODS: We studied adults with biopsy-proven non-alcoholic fatty liver disease (NAFLD) from the multicenter NASH Clinical Research Network (CRN) Adult Database 2 (DB2) cohort study. At-risk-NASH was histologically defined as definite NASH with a NAFLD Activity Score (NAS) ≥ 4 with at least 1 point in each category and a fibrosis stage ≥ 2. We used the Echosens® formula for FAST™ from LSM (kPa), CAP (dB/m), and AST (U/L), and the FAST™-based Rule-Out (FAST™ ≤ 0.35, sensitivity = 90%) and Rule-In (FAST™ ≥ 0.67, specificity = 90%) zones. We determined the following diagnostic performance measures: AUROC, sensitivity (Se), specificity (Sp), positive predictive value (PPV), and negative predictive value (NPV); these were calculated for the total sample and by subgroups of patients and by FibroScan® exam features. We also compared the at-risk NASH diagnostic performance of FAST™ to other non-invasive algorithms: NAFLD fibrosis score (NFS), Fibrosis-4 (FIB-4) index, and AST to platelet ratio index (APRI). RESULTS: The NASH CRN population of 585 patients was 62% female, 79% white, 14% Hispanic, and 73% obese; the mean age was 51 years. The mean (SD) AST and ALT were 50 (37) U/L and 66 (45) U/L, respectively. 214 (37%) had at-risk NASH. The AUROC of FAST™ for at-risk NASH in the NASH CRN study population was 0.81 (95% CI: 0.77, 0.84. Using FAST™-based cut-offs, 35% of patients were ruled-out with corresponding NPV = 0.90 and 27% of patients were ruled-in with corresponding PPV = 0.69. The diagnostic accuracy of FAST™ was higher in non-whites vs. whites (AUROC: 0.91 vs 0.78; p = 0.001), and in patients with a normal BMI vs. BMI > 35 kg/m2 (AUROC: 0.94 vs 0.78, p = 0.008). No differences were observed by other patient characteristics or FibroScan® exam features. The FAST™ score had higher diagnostic accuracy than other non-invasive algorithms for the diagnosis of at-risk NASH (AUROC for NFS, FIB-4, and APRI 0.67, 0.73, 0.74, respectively). CONCLUSION: We validated the FAST™ score for the diagnosis of at-risk NASH in a large, multi-racial population in North America, with a prevalence of at-risk NASH of 37%. Diagnostic performance varies by subgroups of NASH patients defined by race and obesity. FAST™ performed better than other non-invasive algorithms for the diagnosis of at-risk NASH.

Perceptions of Exercise and Its Challenges in Patients With Nonalcoholic Fatty Liver Disease: A Survey-Based Study.

Exercise is a foundational treatment for nonalcoholic fatty liver disease (NAFLD); however, the majority of patients are unable to initiate and maintain effective exercise habits and remain at increased risk for progressive liver disease. Barriers and limitations to exercise in patients with NAFLD have not been fully identified. We performed a single survey of 94 patients with biopsy-proven NAFLD to understand baseline physical activity and sedentary behavior, self-perceived fitness, limitations to exercise, potential solutions to increase physical activity behavior, and perception of exercise as a foundational treatment for NAFLD. For exploratory analyses, we evaluated differences in responses to the survey by grouping severity of hepatic fibrosis as follows: nonalcoholic fatty liver (NAFL); early stage (nonalcoholic steatohepatitis [NASH] F0, NASH F1, NASH F2); and late stage (NASH F3, NASH F4). Zero weekly total physical activity was reported by 29% of patients with NAFLD. Late-stage NASH had significantly lower vigorous (P = 0.024), walking (P = 0.029), total weekly activity (P = 0.043), and current fitness level (P = 0.022) compared to early stage NASH. Overall, 72% of patients with NAFLD reported limitations to exercise, with the greatest proportion citing lack of energy (62%), fatigue (61%), prior/current Injury (50%), and shortness of breath (49%). A preference for personal training to increase their physical activity was indicated by 66% of patients with NAFLD, and 63% preferred exercise over medication to treat NAFLD. Conclusion: The majority of patients with NAFLD have limitations to exercise but prefer exercise as a treatment option for NAFLD in the form of personal training. Patients with NAFLD may have unique physiologic limitations to exercise that worsen with fibrosis severity. Exercise interventions or services that are personalized and scalable may improve sustainability of exercise habits in the long term.

Longitudinal correlations between MRE, MRI-PDFF, and liver histology in patients with non-alcoholic steatohepatitis: Analysis of data from a phase II trial of selonsertib.

BACKGROUND & AIMS: Non-invasive tools for monitoring treatment response and disease progression in non-alcoholic steatohepatitis (NASH) are needed. Our objective was to evaluate the utility of magnetic resonance (MR)-based hepatic imaging measures for the assessment of liver histology in patients with NASH. METHODS: We analyzed data from patients with NASH and stage 2 or 3 fibrosis enrolled in a phase II study of selonsertib. Pre- and post-treatment assessments included centrally read MR elastography (MRE)-estimated liver stiffness, MR imaging-estimated proton density fat fraction (MRI-PDFF), and liver biopsies evaluated according to the NASH Clinical Research Network classification and the non-alcoholic fatty liver disease activity score (NAS). RESULTS: Among 54 patients with MRE and biopsies at baseline and week 24, 18 (33%) had fibrosis improvement (≥1-stage reduction) after undergoing 24 weeks of treatment with the study drug. The area under the receiver operating characteristic curve (AUROC) of MRE-stiffness to predict fibrosis improvement was 0.62 (95% CI 0.46-0.78) and the optimal threshold was a ≥0% relative reduction. At this threshold, MRE had 67% sensitivity, 64% specificity, 48% positive predictive value, 79% negative predictive value. Among 65 patients with MRI-PDFF and biopsies at baseline and week 24, a ≥1-grade reduction in steatosis was observed in 18 (28%). The AUROC of MRI-PDFF to predict steatosis response was 0.70 (95% CI 0.57-0.83) and the optimal threshold was a ≥0% relative reduction. At this threshold, MRI-PDFF had 89% sensitivity and 47% specificity, 39% positive predictive value, and 92% negative predictive value. CONCLUSIONS: These preliminary data support the further evaluation of MRE-stiffness and MRI-PDFF for the longitudinal assessment of histologic response in patients with NASH. LAY SUMMARY: Liver biopsy is a potentially painful and risky method to assess damage to the liver due to non-alcoholic steatohepatitis (NASH). We analyzed data from a clinical trial to determine if 2 methods of magnetic resonance imaging - 1 to measure liver fat and 1 to measure liver fibrosis (scarring) - could potentially replace liver biopsy in evaluating NASH-related liver injury. Both imaging methods were correlated with biopsy in showing the effects of NASH on the liver.

Serum Interleukin-8, Osteopontin, and Monocyte Chemoattractant Protein 1 Are Associated With Hepatic Fibrosis in Patients With Nonalcoholic Fatty Liver Disease.

The severity of hepatic fibrosis is the primary predictor of liver-related morbidity and mortality in patients with nonalcoholic fatty liver disease (NAFLD). Unfortunately, noninvasive serum biomarkers for NAFLD-associated fibrosis are limited. We analyzed baseline serum samples for 24 cytokines of 97 patients with biopsy-proven NAFLD. These patients were prospectively enrolled in a clinical study (ClinicalTrials.gov NCT00794716) to identify cytokines associated with liver fibrosis in patients with nonalcoholic steatohepatitis. Patients were stratified according to severity of hepatic fibrosis (mild, stage 0-1, n = 37; moderate, stage 2, n = 40; and advanced, stage 3-4, n = 20) while controlling for age, race, sex, body mass index, and diabetes mellitus. Interleukin-8 (IL-8), osteopontin (OPN), and monocyte chemoattractant protein 1 (MCP1) were associated with liver fibrosis (P < 0.001, P = 0.005, P = 0.016, respectively). After controlling for steatosis, lobular inflammation, hepatocyte ballooning, age, sex, body mass index, diabetes mellitus, hypertension, and metabolic syndrome status, IL-8 remained strongly associated with fibrosis (P = 0.001). Furthermore, IL-8 was also a strong predictor of increased fibrotic liver injury compared to established markers of hepatic fibrosis. Hepatic gene expression from 72 patients with NAFLD (n = 40 mild fibrosis; n = 32 advanced fibrosis) from the Duke University Health System NAFLD Clinical Database and Biorepository revealed IL-8, MCP1, and OPN gene expression to be increased and differentially expressed in patients with advanced hepatic fibrosis. Thus, serum IL-8, MCP1, and OPN may reflect up-regulated gene expression during liver fibrosis in NAFLD. Conclusion: Serum IL-8, MCP1, and OPN may serve as a test for advanced hepatic fibrosis in NAFLD and thus reveal novel targets for antifibrotic therapies. The increased serum IL-8, MCP1, and OPN that correspond with associated hepatic gene expression lend strength to such analytes as ideal surrogate serum biomarkers for severity of hepatic fibrosis.

Whole-Exome Sequencing Study of Extreme Phenotypes of NAFLD.

Nonalcoholic fatty liver disease (NAFLD) is a heterogeneous disease with highly variable outcomes. Patients with simple steatosis typically experience a benign course, whereas those with more advanced liver injury, nonalcoholic steatohepatitis (NASH), and advanced stage fibrosis suffer increased risk for complications such as cirrhosis, hepatic decompensation, and liver cancer. Genetic variants in patatin-like phospholipase domain-containing 3 (PNPLA3) and transmembrane 6 superfamily member 2 (TM6SF2) and clinical factors including diabetes, obesity, and older age increase a patient's risk for NASH, advanced fibrosis, and worse outcomes. Despite substantial investigation and identification of some common variants associated with NAFLD and advanced fibrosis, the genetics and functional mechanisms remain poorly understood. This study aimed to identify genetic variants by whole-exome sequencing of NAFLD phenotypes to provide novel insights into mechanisms behind NAFLD pathogenesis and variability. We sequenced 82 patients with liver biopsy-confirmed NAFLD and 4455 population controls. NAFLD patients were divided into extreme phenotypes based on liver fibrosis stage and clinical risk factors to investigate rare variants that might predispose to or protect from advanced NAFLD fibrosis. We compared NAFLD extremes to each other and individually to population controls, exploring genetic variation at both the single-variant and gene-based level. We replicated known associations with PNPLA3 and TM6SF2 and advanced fibrosis, despite sample-size limitations. We also observed enrichment of variation in distinct genes for progressor or protective NAFLD phenotypes, although these genes did not reach statistical significance. Conclusion: We report the first whole-exome sequencing study of genetic variation in liver biopsy-confirmed NAFLD susceptibility and severity, using a small cohort of extreme NAFLD phenotypes and a large cohort of population controls.

Animal models of steatohepatitis.

Animal models of hepatic steatosis and steatohepatitis have improved our understanding of the pathogenesis of non-alcoholic fatty liver disease (NAFLD). Three models, genetically obese ob/ob mice, lipoatrophic mice and normal rats fed choline-deficient, methionine-restricted diets, have been particularly informative. All support the multiple 'hit' hypothesis for NAFLD pathogenesis that suggests that fatty livers are unusually vulnerable to oxidants and develop steatohepatitis when secondary insults generate sufficient oxidants to cause liver cell death and inflammation. Steatohepatitis, in turn, increases sensitivity to other insults that induce hepatic fibrosis, promoting the evolution of cirrhosis. Early during NAFLD pathogenesis, inhibitor kappa kinase beta (IKKbeta), an enzyme that induces tumour necrosis factor alpha (TNFalpha) and other proinflammatory cytokines, is activated and this causes insulin resistance. Inhibition of IKKbeta or TNFalpha improves insulin sensitivity, steatosis and steatohepatitis in animals, suggesting novel strategies to prevent and treat early NAFLD in humans.