Wong, Vincent Wai‐Sun

ABSTRACT Although physical activity (PA) is crucial in the prevention and clinical management of nonalcoholic fatty liver disease, most individuals with this chronic disease are inactive and do not achieve recommended amounts of PA. There is a robust and consistent body of evidence highlighting the benefit of participating in regular PA, including a reduction in liver fat and improvement in body composition, cardiorespiratory fitness, vascular biology, and health-related quality of life. Importantly, the benefits of regular PA can be seen without clinically significant weight loss. At least 150 min of moderate or 75 min of vigorous intensity PA are recommended weekly for all patients with nonalcoholic fatty liver disease, including those with compensated cirrhosis. If a formal exercise training program is prescribed, aerobic exercise with the addition of resistance training is preferred. In this roundtable document, the benefits of PA are discussed, along with recommendations for 1) PA assessment and screening; 2) how best to advise, counsel, and prescribe regular PA; and 3) when to refer to an exercise specialist.

Background and Aims: We present findings from the inaugural American College of Sports Medicine (ACSM) International Multidisciplinary Roundtable, which was convened to evaluate the evidence for physical activity as a means of preventing or modifying the course of NAFLD. Approach and Results: A scoping review was conducted to map the scientific literature and identify key concepts, research gaps, and evidence available to inform clinical practice, policymaking, and research. The scientific evidence demonstrated regular physical activity is associated with decreased risk of NAFLD development. Low physical activity is associated with a greater risk for disease progression and extrahepatic cancer. During routine health care visits, all patients with NAFLD should be screened for and counseled about physical activity benefits, including reduction in liver fat and improvement in body composition, fitness, and quality of life. While most physical activity benefits occur without clinically significant weight loss, evidence remains limited regarding the association between physical activity and liver fibrosis. At least 150 min/wk of moderate or 75 min/wk of vigorous-intensity physical activity are recommended for all patients with NAFLD. If a formal exercise training program is prescribed, aerobic exercise with the addition of resistance training is preferred. Conclusions: The panel found consistent and compelling evidence that regular physical activity plays an important role in preventing NAFLD and improving intermediate clinical outcomes. Health care, fitness, and public health professionals are strongly encouraged to disseminate the information in this report. Future research should prioritize determining optimal strategies for promoting physical activity among individuals at risk and in those already diagnosed with NAFLD.

Abstract Cirrhosis, highly prevalent worldwide, develops after years of hepatic inflammation triggering progressive fibrosis. Currently, the main etiologies of cirrhosis are non‐alcoholic fatty liver disease and alcohol‐related liver disease, although chronic hepatitis B and C infections are still major etiological factors in some areas of the world. Recent studies have shown that liver fibrosis can be assessed with relatively high accuracy noninvasively by serological tests, transient elastography, and radiological methods. These modalities may be utilized for screening for liver fibrosis in at‐risk populations. Thus far, a limited number of population‐based studies using noninvasive tests in different areas of the world indicate that a significant percentage of subjects without known liver disease (around 5% in general populations and a higher rate −18% to 27%‐in populations with risk factors for liver disease) have significant undetected liver fibrosis or established cirrhosis. Larger international studies are required to show the harms and benefits before concluding that screening for liver fibrosis should be applied to populations at risk for chronic liver diseases. Screening for liver fibrosis has the potential for changing the current approach from diagnosing chronic liver diseases late when patients have already developed complications of cirrhosis to diagnosing liver fibrosis in asymptomatic subjects providing the opportunity of preventing disease progression.

Background and Aims Electronic health record (EHR)‐based research allows the capture of large amounts of data, which is necessary in NAFLD, where the risk of clinical liver outcomes is generally low. The lack of consensus on which International Classification of Diseases (ICD) codes should be used as exposures and outcomes limits comparability and generalizability of results across studies. We aimed to establish consensus among a panel of experts on ICD codes that could become the reference standard and provide guidance around common methodological issues. Approach and Results Researchers with an interest in EHR‐based NAFLD research were invited to collectively define which administrative codes are most appropriate for documenting exposures and outcomes. We used a modified Delphi approach to reach consensus on several commonly encountered methodological challenges in the field. After two rounds of revision, a high level of agreement (>67%) was reached on all items considered. Full consensus was achieved on a comprehensive list of administrative codes to be considered for inclusion and exclusion criteria in defining exposures and outcomes in EHR‐based NAFLD research. We also provide suggestions on how to approach commonly encountered methodological issues and identify areas for future research. Conclusions This expert panel consensus statement can help harmonize and improve generalizability of EHR‐based NAFLD research.

SummaryDue to the introduction of newer, more efficacious treatment options, there is a pressing need for policy makers and public health officials to develop or adapt national hepatitis C virus (HCV) control strategies to the changing epidemiological landscape. To do so, detailed, country‐specific data are needed to characterize the burden of chronic HCV infection. In this study of 17 countries, a literature review of published and unpublished data on HCV prevalence, viraemia, genotype, age and gender distribution, liver transplants and diagnosis and treatment rates was conducted, and inputs were validated by expert consensus in each country. Viraemic prevalence in this study ranged from 0.2% in Hong Kong to 2.4% in Taiwan, while the largest viraemic populations were in Nigeria (2 597 000 cases) and Taiwan (569 000 cases). Diagnosis, treatment and liver transplant rates varied widely across the countries included in this analysis, as did the availability of reliable data. Addressing data gaps will be critical for the development of future strategies to manage and minimize the disease burden of hepatitis C.

SummaryFactors influencing the morbidity and mortality associated with viremic hepatitis C virus (HCV) infection change over time and place, making it difficult to compare reported estimates. Models were developed for 17 countries (Bahrain, Bulgaria, Cameroon, Colombia, Croatia, Dominican Republic, Ethiopia, Ghana, Hong Kong, Jordan, Kazakhstan, Malaysia, Morocco, Nigeria, Qatar and Taiwan) to quantify and characterize the viremic population as well as forecast the changes in the infected population and the corresponding disease burden from 2015 to 2030. Model inputs were agreed upon through expert consensus, and a standardized methodology was followed to allow for comparison across countries. The viremic prevalence is expected to remain constant or decline in all but four countries (Ethiopia, Ghana, Jordan and Oman); however, HCV‐related morbidity and mortality will increase in all countries except Qatar and Taiwan. In Qatar, the high‐treatment rate will contribute to a reduction in total cases and HCV‐related morbidity by 2030. In the remaining countries, however, the current treatment paradigm will be insufficient to achieve large reductions in HCV‐related morbidity and mortality.

SummaryThe hepatitis C virus (HCV) epidemic was forecasted through 2030 for 17 countries in Africa, Asia, Europe, Latin America and the Middle East, and interventions for achieving the Global Health Sector Strategy on viral hepatitis targets—“WHO Targets” (65% reduction in HCV‐related deaths, 90% reduction in new infections and 90% of infections diagnosed by 2030) were considered. Scaling up treatment and diagnosis rates over time would be required to achieve these targets in all but one country, even with the introduction of high SVR therapies. The scenarios developed to achieve the WHO Targets in all countries studied assumed the implementation of national policies to prevent new infections and to diagnose current infections through screening.

Liver fibrosis is the most important predictor of mortality in nonalcoholic fatty liver disease (NAFLD). Quantitative risk of mortality by fibrosis stage has not been systematically evaluated. We aimed to quantify the fibrosis stage–specific risk of all‐cause and liver‐related mortality in NAFLD. Through a systematic review and meta‐analysis, we identified five adult NAFLD cohort studies reporting fibrosis stage–specific mortality (0‐4). Using fibrosis stage 0 as a reference population, fibrosis stage–specific mortality rate ratios (MRRs) with 95% confidence intervals (CIs) for all‐cause and liver‐related mortality were estimated. The study is reported according to the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses statement. Included were 1,495 NAFLD patients with 17,452 patient years of follow‐up. Compared to NAFLD patients with no fibrosis (stage 0), NAFLD patients with fibrosis were at an increased risk for all‐cause mortality, and this risk increased with increases in the stage of fibrosis: stage 1, MRR = 1.58 (95% CI 1.19‐2.11); stage 2, MRR = 2.52 (95% CI 1.85‐3.42); stage 3, MRR = 3.48 (95% CI 2.51‐4.83); and stage 4, MRR = 6.40 (95% CI 4.11‐9.95). The results were more pronounced as the risk of liver‐related mortality increased exponentially with each increase in the stage of fibrosis: stage 1, MRR = 1.41 (95% CI 0.17‐11.95); stage 2, MRR = 9.57 (95% CI 1.67‐54.93); stage 3, MRR = 16.69 (95% CI 2.92‐95.36); and stage 4, MRR = 42.30 (95% CI 3.51‐510.34). Limitations of the study include an inability to adjust for comorbid conditions or demographics known to impact fibrosis progression in NAFLD and the inclusion of patients with simple steatosis and nonalcoholic steatohepatitis without fibrosis in the reference comparison group. Conclusion: The risk of liver‐related mortality increases exponentially with increase in fibrosis stage; these data have important implications in assessing the utility of each stage and benefits of regression of fibrosis from one stage to another. (H epatology 2017;65:1557‐1565).