The European NAFLD Registry: A real-world longitudinal cohort study of nonalcoholic fatty liver disease

Non-Alcoholic Fatty Liver Disease (NAFLD), a progressive liver disease that is closely associated with obesity, type 2 diabetes, hypertension and dyslipidaemia, represents an increasing global public health challenge. There is significant variability in the disease course: the majority exhibit only fat accumulation in the liver but a significant minority develop a necroinflammatory form of the disease (non-alcoholic steatohepatitis, NASH) that may progress to cirrhosis and hepatocellular carcinoma. At present our understanding of pathogenesis, disease natural history and long-term outcomes remain incomplete. There is a need for large, well characterised patient cohorts that may be used to address these knowledge gaps and to support the development of better biomarkers and novel therapies. The European NAFLD Registry is an international, prospectively recruited observational cohort study that aims to establish a large, highly-phenotyped patient cohort and linked bioresource. Here we describe the infrastructure, data management and monitoring plans, and the standard operating procedures implemented to ensure the timely and systematic collection of high-quality data and samples. Already recruiting subjects at secondary/tertiary care centres across Europe, the Registry is supporting the European Union IMI2-funded LITMUS ‘Liver Investigation: Testing Marker Utility in Steatohepatitis’ consortium, which is a major international effort to robustly validate biomarkers that diagnose, risk stratify and/or monitor NAFLD progression and liver fibrosis stage. The European NAFLD Registry has the demonstrable capacity to support research and biomarker development at scale and pace.


Introduction
Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide and represents a major global public health challenge. It is characterised by the increased accumulation of hepatic fat (> 5%) and is closely linked with the presence of the metabolic syndrome and its components: obesity, type 2 diabetes mellitus, hypertension and dyslipidaemia. [1,2] The exclusion of other causes of The European NAFLD Registry is actively recruiting at sites across Europe using a 'hub-and-spoke' model. National lead sites (red), recruiting centres (blue). Additional recruitment is also taking place at selected sites in USA. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.) T. Hardy, et al. Contemporary Clinical Trials 98 (2020) 106175 fat accumulation such as excessive alcohol consumption is traditionally part of the disease definition although a recently proposed revised nomenclature, metabolic-dysfunction associated fatty liver disease (MAFLD), places emphasis on the pre-eminence of metabolic-dysfunction. [3] NAFLD is a spectrum of progressive liver disease comprising steatosis (non-alcoholic fatty liver, NAFL), in which excessive hepatic fat is present, and non-alcoholic steatohepatitis (NASH), a necroinflammatory form of the condition marked by histological inflammation and hepatocyte ballooning that leads to progressive liver fibrosis. NAFLD is a cause of significant morbidity and mortality; left untreated, fibrosis may progress to cirrhosis and can result in end-stage liver disease or hepatocellular carcinoma (HCC). [4][5][6] The prevalence estimates of NAFLD vary widely according to the modality used to detect NAFLD and the geographical area. A recent meta-analysis estimated the global prevalence of NAFLD to be 25% of adults, with the highest estimates in the Middle East and South America (32% and 31%, respectively) and the lowest estimates in Africa (14%); the estimates for Asia, the USA, and Europe were 27%, 24% and 23%, respectively. [2,7] Modelling studies predict a steady increase in disease incidence in China, France, Germany, Italy, Japan, Spain, United Kingdom, and United States that is accompanied by an increase in liver transplantation, HCC and mortality from liver and non-liver-related causes. [8] The associated economic burden is substantial and, without a concerted public health response, will continue to increase as more people are affected. [9][10][11] NAFLD is characterised by substantial inter-patient variability in terms of severity and rate of progression. [12] Despite there being a large at-risk population, only a minority experience significant morbidity. The factors that determine transition from NAFL to NASH, and subsequent progression of fibrosis to cirrhosis are incompletely understood. Thus, there are key knowledge gaps, in particular limited clarity on modifiers of disease natural history and an incomplete understanding of disease pathophysiology. These issues contribute to the lack of tractable non-invasive biomarkers of disease severity that hinder the diagnosis, risk stratification and monitoring of patients, and the absence of approved pharmacological therapies.
Although many people have NAFLD, few are sufficiently well characterised for their data to be tractable in research. This is because histopathological examination of liver tissue is required to differentiate NAFL from NASH, grade steatohepatitis activity and accurately stage fibrosis. [5] However, liver biopsy is not widely utilised outside specialist centres as it is resource-intensive and carries a small but appreciable risk of complications. Therefore, a broad collaborative effort is required to pool sufficient data from comprehensively phenotyped patients at specialist centres to assemble an adequately sized cohort that may be leveraged to support research. The European NAFLD Registry (ENR) is an innovative, international patient registry with an associated bioresource that is assembling a large, well-characterised patient cohort specifically to support translational and discovery science.

Table 1
Current recruitment sites by country.

Overview
The European NAFLD Registry is a prospectively recruited, international observational study to assemble a cohort of highly-phenotyped patients across the full spectrum of NAFLD that will facilitate crosssectional and longitudinal analyses (clinicaltrials.gov registration NCT04442334) [13]. The comprehensive dataset includes clinical information, liver histopathology and imaging data derived from healthcare records during routine medical care and is supplemented by lifestyle and quality of life data, as well as biological sample collection.
The European NAFLD Registry infrastructure hosts a uniform dataset of patient level data that is split into two distinct sub-sections: i. The 'Metacohort': comprises prospectively recruited NAFLD cases that consented to participate during recruitment for European studies into NAFLD pathogenesis conducted from 2010 to December 2017 (i.e. the FP7-FLIP, H2020-EPoS and HEPAmet cohorts) [14][15][16], plus cases with compatible consent and data collection processes derived from previous investigator-led single-centre cohorts. Data from these cohorts have been integrated into a single dataset whilst maintaining data quality and retaining knowledge of the source. ii. The 'LITMUS Study Cohort': comprises prospectively recruited NAFLD cases acquired since 1st January 2018 as part of the IMI2funded LITMUS project [17]. Recruitment is ongoing across Europe according to a common Master Study Protocol with a comprehensive data monitoring process and standard operating procedures for sample handling implemented. Recruitment is currently active at > 25 centres in 13 countries ( Fig. 1 and Table 1.) Patients with that are enrolled into the European NAFLD Registry will be followed-up for up to 10-years to allow assessment of long-term outcomes.

Objectives
The primary objective of the European NAFLD Registry observational study is to assemble a 'real-world' cohort of well-characterised patients across the full spectrum of NAFLD and to collect associated clinical information, biological samples and imaging data for crosssectional and longitudinal analyses to support research into disease natural history.
Key secondary objectives are to support research addressing the pathophysiology of NAFLD using a range of state-of-the-art scientific techniques with integrated bioinformatics. Additional secondary measures include the study of dietary habits, lifestyle/activity factors and symptom burden.
To characterise and integrate key intrinsic factors multiple 'omics' approaches (genetic, epigenetic, transcriptomic, metabolomic, proteomic and metagenomic) will be applied to understand inter-individual variation in severity of hepatic injury, serum and hepatic 'omic' profiles and their interaction with environmental (behavioural/ dietary/lifestyle) factors that determine how a patient feels, how the disease progresses over time and long term outcomes. We envisage these activities will lead to a substantial and definitive atlas of pathophysiological variation across the spectrum of progressive NAFLD, identify predictors of long-term outcome and support identification of novel biomarkers and therapeutic targets.
In terms of application, the present focus of activity for the European NAFLD Registry is to support the work of the European Union IMI2-funded LITMUS 'Liver Investigation: Testing Marker Utility in Steatohepatitis' consortium (https://www.imi.europa.eu/projectsresults/project-factsheets/litmus). This ambitious project brings together clinicians and scientists from prominent academic centres across Europe with companies from the European Federation of Pharmaceutical Industries and Associations (EFPIA). Their common goals are developing and validating biomarkers for testing NAFLD and seeks to establish a defined set of biomarkers that singly or in combination, enable detection and monitoring of disease progression to/  regression from NAFL through NASH to fibrosis and cirrhosis. Through the Registry, research is powered to provide the required clarity on biomarker analytical and clinical validity at scale and pace, generating the requisite level of high-quality data to support biomarker validation and evidence needed for regulatory qualification under the joint EMA Committee for Medicinal Products for Human Use (CHMP) and the US Food and Drug Administration (FDA) processes.

Organisation & oversight
The European NAFLD Registry operates across multiple territories and so a comprehensive organisational and oversight structure has been established ( Fig. 2) that defines lines of responsibility as well as project management, data management, data monitoring and sample handling processes. Oversight and recruitment into the Registry are structured according to three tiers of geographical hierarchy: central leadership and coordination, national oversight and site level delivery.
Coordination of the study, including establishing the European NAFLD Registry Master Protocol, defining standard operating procedures, management of the web-based eCRF database, controlling data access and biological sample use are managed centrally by the Registry Management Team. This group comprises the Chief Investigator, Study Managers, Data Managers, Ethics Lead and representatives from the Registry Central Biobank. However, the conduct of the study according to these centrally defined processes, including responsibility for study sponsorship, regulatory compliance, gaining the necessary national and/or local ethical approvals for recruitment and site data-monitoring as centrally defined is devolved to a budget-holding National Lead Investigator in each country (Table 1). These senior investigators are experienced clinical trialists with extensive knowledge of the national research frameworks in which they operate. Thus, the Registry is able to tailor its activities to varying national research ecosystems whist ensuring robust data collection in compliance with the International Conference on Harmonisation -Good Clinical Practice (ICH-GCP) requirements [18].

Ethical practice & regulatory compliance
All subject recruitment and informed consent processes at recruitment centres are conducted in compliance with nationally accepted practice in the respective territory and in accordance with the World Medical Association Declaration of Helsinki 2018, the Charter of Fundamental Rights of the European Union (2000/C 364/01), and the principles defined by the Belmont Report. Data is collected and processed in accordance with the applicable General Data Protection Regulation (EU) 2016/679 (GDPR) legislation.
For the 'LITMUS Study', a named National Lead Investigator oversees the conduct of recruitment at sites in their respective country (Table 1). An Ethics Lead curates the central LITMUS Study Trial Master File (L-TMF) to ensure all necessary ethical approvals are in place for each territory and reports annually to an independent ethics guardian. Supplementary Material 1 provides details of the associated ethical approvals by country.

Database
Personal data including clinical data are collected, and such data are protected in accordance with the European General Data Protection Regulation (GDPR). Data is held within the Registry in a pseudoanonymised (linked-anonymised) form to avoid personally identifiable data transfer or processing outside a subject's usual clinical care team at the recruiting site.
A purpose-built MySQL relational database has been developed to facilitate data capture during recruitment into the Registry. The webaccessible secure front-end database comprises 14 related electronic clinical record form (eCRF) data-tables and contains around 1200 data fields, equating to approximately 1-2 megabytes of data per subject and is designed to fulfil the regulatory requirements for record keeping [19]. Data are held in a Clinical Data Interchange Standards Consortium (CDISC, www.cdisc.org) compliant format to aid information system interoperability for future collaborative projects. The database holding the project user records and collected records from sites is hosted on a multi-machine replication cluster with multiple physical servers. In the event of machine failure or catastrophic data loss, one of the remaining database servers would be promoted to become the master server for the European NAFLD Registry application. Database records are archived to a separate physical server three times daily, once per day for the previous 31 days and once per month for the previous 12 months. In addition, an archive copy of the data is retained on Newcastle University's Research Data Warehouse according to local information security policy. This ensures a copy of the data is available for up to tenyears after the last date of access. Network access to the database is controlled by specific role at the individual level.

Inclusion/exclusion criteria
The study population is patients aged ≥18 years with risk factors for NAFLD that will be recruited in hepatology clinics and/or bariatric surgery units primarily distributed at centres across Europe. Patients are invited to participate in both the cross-sectional and longitudinal aspects of the study but may drop-out of the latter at any point if they wish. Two main sources of patients are targeted: i. Patients investigated for suspected NAFLD in hepatology clinics, e.g.
referred for the investigation of abnormal liver biochemistry tests noted in primary care. ii. Patients seen in bariatric surgery units for planned surgical weight loss treatment for morbid obesity.
Inclusion and exclusion criteria are presented in Table 2. In summary, for non-cirrhotic patients, confirmation of the diagnosis of NAFLD must be made histologically, whereas patients with radiological evidence of cirrhosis in the absence of an alternative aetiology may be recruited if at least two features indicative of the metabolic syndrome are present. Secondary causes of steatosis, including high alcohol consumption, and other coexisting liver diseases are exclusionary.

Study procedures
Study processes have been designed to minimise the burden of participation on patients. As much as possible, data and samples are collected alongside scheduled routine-care clinical attendance. Following signed informed consent, patients are assigned a unique 'study participant identification code' (SPIC). This ensures data are held in the Registry in a linked-anonymised form to preserve patient confidentiality. An Investigator Handbook has been developed to assist study staff at sites in application of standardised processing methods to avoid any centre-related preanalytical bias (Supplementary Material 2).

Data collection
A comprehensive dataset is collected from the medical notes at the 'baseline' enrolment clinical attendance (usually coincident with a liver biopsy). This detailed dataset includes demographics, anthropometrics, a range of clinical (co-morbidities, current medication), laboratory (clinical haematology, biochemistry, immunology), histopathological and radiological data (Table 3).
Diagnostic imaging data are collected for all patients undergoing clinically indicted investigations. These include routine diagnostic ultrasound and Fibroscan™ (vibration-controlled transient elastography [VCTE]) as well as any other modalities that may be used as part of local practice at recruiting sites. In addition, selected patients are invited to opt-in to participate in a nested imaging study in which MRI-PDFF, MR LiverMultiScan™, deMILI, and MR Apparent Diffusion Coefficient, as well as elastography (acoustic radiation force impulse [ARFI]; and magnetic-resonance elastography [MRE]) are captured outwith standard care.
In addition, the following lifestyle and symptom burden questionnaires are collected: • International Physical Activity Questionnaire (IPAQ) [26].
Thereafter, 'follow-up event' data are collected annually at scheduled out-patient clinic attendances. In addition, data collection may be triggered if the patient undergoes a subsequent clinically indicated liver biopsy or if a significant 'clinical event' occurs. Target events are listed in Table 4 and focus particularly on death, major adverse cardiovascular events (MACE), hepatic events (progression to cirrhosis, hepatic decompensation and/or HCC) and extra-hepatic malignancy.
Where healthcare systems permit (for example, the UK's National Health Service "NHS Digital" platform), patients are asked to allow their national health records to be flagged to facilitate capture of longterm outcome events if they are lost to follow up at the recruitment site. In addition, if a patient were to move their regular care provider from one participating centre to another, the patient can transfer their unique SPIC to the new participating site so that the new site can continue to update the patient's registry record.

Sample Collection & Processing
Following informed consent and study code (SPIC) assignment, patients provide biological samples for research use at enrolment (baseline). Blood samples are drawn in the fasted state as close to the date of the liver biopsy as possible ( ± 30 days). Collected biological samples include: whole blood for serum and plasma isolation, for genomic DNA extraction, then for circulating miRNA and circulating cfDNA extraction from plasma; stool for microbial DNA extraction; urine; and liver tissue (formalin-fixed, paraffin embedded [FFPE] and snap-frozen samples), if the patient is undergoing a clinically indicated liver biopsy. Samples to be collected are summarised in Fig. 3, which provides an overview of how samples are processed and transferred to the central biobank facility. Faecal microbiome analyses are known to be significantly impacted by different DNA extraction methods, therefore all stool DNA extractions are centrally performed at the IBBL with a  Fig. 3. Summary of biological sample collection processing. At enrolment (Baseline) and at subsequent annual follow-up visits, or if a clinically significant event occurs, a range of samples will be collected from patients participating in The European NAFLD Registry. These will be processed according to defined SOPs and shipped to the Central Biobank facility for storage. validated method [27]. At subsequent annual routine hospital attendances or major clinical events, patients are asked to provide follow-up biological samples for longitudinal studies. To ensure high quality samples are consistently collected across all sites and to minimise preanalytical variation, standard operating procedures have been established and are fully described in the Investigator Handbook (Supplementary Material 2).

Central histological interpretation & digitisation of liver biopsies
Histopathological assessment of liver biopsy remains the widely accepted, albeit imperfect, reference standard for assessing severity of liver disease [28]. As well as issues with sampling error [29], there remain concerns regarding potential interobserver variability in assessment. To address these issues, the European NAFLD Registry has adopted a number of measures to ensure data quality: Network (CRN) "NAFLD Activity Score" (NAS) and the FLIP "Steatosis -Activity -Fibrosis" (SAF) systems [30,31]. Whilst these scoring systems differ in important ways, all measure four key histological characteristics: grade of steatosis, severity of hepatocellular injury (hepatocyte ballooning) and lobular inflammation, and stage of fibrosis (summarised in Table 5). Fibrosis stage is recorded using both the NASH CRN/SAF 5-tier (F0-4) and the EPoS 7-tier (F0-6) fibrosis staging systems (including sub-staging of cirrhosis into stages 6a, 6b and 6c according to modified Laennec staging) [32,33]. In addition to histological scoring of these standard features, pathologists also assess the intensity of portal inflammation, the presence of Mallory-Denk bodies and determine a broad diagnostic category (i.e. normal, NAFL, definite NASH, fibrosis/cirrhosis without steatosis consistent/not consistent with NAFLD). All data are captured using a standardised reporting proforma. iii. The Registry Histopathology Group (RHG) comprises ten expert hepatopathologists (Table 6) who participate in a face-to-face harmonisation meetings to align on histological criteria and have demonstrated close interobserver concordance [31]. Pairs of hepatopathologists from this group independently double-score liver biopsies with reference to a digital atlas of NAFLD histology that has been prepared by the group leaders (Supplementary Material 3 and via the European Society of Pathology website: https:// tinyurl.com/LITMUS-Histology). If the two scores within a pair are found to be discrepant (by ≥2 points for steatosis or inflammation, and ≥ 1 for ballooning or fibrosis) the biopsy is referred to a consensus adjudication panel. To further ensure data quality, the adjudication panel reviews a random sample of biopsies for quality control. An administrator assigns the liver biopsies to the pathologist pairs, completes the final report for each case based on the agreed scores and uploads the histological data in the NAFLD Registry.
Although semiquantitative scoring systems are used in many clinical trials [34][35][36][37][38], it is recognised that scoring systems provide a nonlinear, semiquantitative or categorical assessment of disease that may limit precision and granularity of data, particularly in the context of subtle changes over time or at the boundary between two categories, where misclassification may occur. To supplement these efforts, the European NAFLD Registry also captures data from a number of novel automated quantitative assessment measures based on digitised biopsy images and second harmonic generation/two-photon excitation microscopy (Genesis200®, HistoIndex, Singapore), leveraging machine learning and artificial intelligence approaches to add further value to Table 5 Comparison of the SAF Score and the NAFLD Clinical Research Network Score for the histological grading and staging of NAFLD. SAF score [42] NASH CRN NAFLD activity score [30] Histological

Data monitoring
Monitoring is a crucial quality control process to establish that study activities are being carried out as intended, so that deficiencies can be addressed, and is critical to the protection of human subjects, the conduct of high-quality studies and the generation of robust clinical trial data. [40]. The European NAFLD Registry has adopted a risk-based monitoring approach as recommended by the FDA in its guidance document Oversight of Clinical Investigations -A Risk-Based Approach to Monitoring (August 2013) [40,41]. This dynamic, iterative process focuses oversight activities on preventing or mitigating important and likely risks to data quality and trial integrity. Thus, findings determine subsequent actions (for example, targeted additional training of clinical investigators at sites, clarification of protocol requirements) to ensure the requisite levels of data quality are achieved. Due to the non-interventional nature of the Registry, risk-assessment has determined that the likelihood of direct harm to participants is minimal and so monitoring primarily focusses on ensuring that conduct is in compliance with the protocol and that study data are complete, accurate and verifiable. In line with the organisational structure of the Registry, monitoring activities are structured as three tiers: central oversight of data integrity, country-level source-data verification checks with external monitors visiting sites and site-level internal data checks conducted by the local research teams.
Central monitoring is conducted by the central Registry Management Team (Fig. 2). Central data managers perform consistency checks of data entered into the Registry at least every 6 months. These include review of enrolment rates against site and study targets; data validation for completeness and plausibility; and oversight of monitoring activities. Any inconsistencies, errors or omissions detected are flagged to the recruiting site to address. The Registry Management Team and Central Biobank also oversees biological sample management and cross-referencing of the biobank catalogue with the Registry database to ensure samples are received and logged appropriately.
At the country level, National Clinical Leads serve as the national chief investigator in their territory and are responsible for compliance and on-site monitoring. The National Clinical Leads carry out Site Initiation visits providing information to sites on study background, protocol, and data management procedures. Inconsistencies, errors or omissions flagged by the Registry Management Team are highlighted to the National Clinical Lead who ensures the recruiting site checks and amends errors as necessary. A key role of the National Clinical Lead is to appoint site monitors to ensure compliance with GCP, data consistency across sites in a territory and appropriateness of training. Site monitoring includes several important activities, but crucially source data verification (SDV). A first monitoring visit is conducted at each site within three months of the first subject enrolled into the European NAFLD Registry, once per year of the study and until three months after the recruitment of the last subject. Briefly, the first two participants in the study are subject to 100% SDV through the entirety of the project; if major errors/critical findings are found in these patients, the subsequent two patients recruited will follow the same monitoring procedure through the study. Additional activities include review of signed consent forms for all participants and authority approvals are in place.
The final layer of oversight comes at a site-level. Site level monitoring is carried out by an independent member of the local research team, not the individual who entered the data, and includes confirmation of consent, data collection according to study protocol and ensuring complete datasets. Protocol deviations are documented in each participant record using the protocol deviation form and reported to the National Clinical Lead. Internal monitoring tasks include checks that: all participants are consented on the most up-to-date, approved informed consent form in effect at their last visit and that all forms have been completed correctly and the consent date entered into the Registry; data being collected is consistent with what is required by the study protocol and an accurate transcription of the source documents, with special attention being paid to accuracy of reported clinical events and associated investigations.

Data management
The European NAFLD Registry has a comprehensive data management plan (DMP) to allow secure management of generated data sets and plans for publications, data access and preservation policies. The DMP will be regularly updated to reflect other data sets that may be developed within the European NAFLD Registry, which aims to provide accurate and high-quality data to the research community, so that the Registry will contribute to future advancements in the field of advanced diagnostics. Dissemination of research data is planned in the form of publications in scientific journals and/or presented in scientific or other meetings for the benefit of the wider medical community. Participants will not be identifiable from such published data nor in any datasets that may be placed in the public domain.

Discussion
The European NAFLD Registry represents a major international effort involving leading secondary/tertiary care centres in Europe, to prospectively recruit patients into an observational study exploring the pathophysiology of progressive liver disease, disease outcomes and associated predictive factors in patients with NAFLD. Importantly, data generated from this study will address key unmet medical needs: the European NAFLD Registry underpins the LITMUS consortium goal of establishing a defined set of biomarkers that singly or in combination, enable detection and monitoring of disease progression to/regression Table 6 Organisation of the Registry Histopathology Group: pairing and adjudication panel.
from NAFL through NASH to fibrosis and cirrhosis that may be used in clinical trials.
The European NAFLD Registry seeks to cognise the variability in NAFLD disease course by leveraging large sets of integrated '-omic' data to better understand the pathophysiological processes that underpin NAFLD disease severity and progression. It also collates existing prospectively recruited cohorts to permit better granularity of disease outcomes. Together, the European NAFLD Registry data set will allow better correlation of biomarkers with disease diagnosis, prognosis and monitoring, permitting the advent of new pharmacotherapy, which is desperately needed.
The strengths of the Registry are its large sample size, international recruitment, standardised procedures, and fastidious data monitoring plans. The Registry aims not only to collect data of the highest quality, but also to have the ability to prove that the data is of the utmost veracity. Built within the Registry is a geographical hierarchy that facilitates implementation of a clinical monitoring plan that ultimately verifies the high quality of the data collected. A unique strength of the Registry is its ability to provide integrated datasets of both cross sectional and longitudinal analysis in the same patient to ascertain causal relationships and mechanisms in disease progression. This capability will facilitate unsupervised data exploration and analysis to develop novel research hypothesis by artificial intelligence/machine learning in addition to end-user directed hypothesis testing. With approved pharmacotherapies for NASH likely to become available in the near future, the European NAFLD Registry platform also has the capability to support authority requested post-marketing surveillance studies (post-authorisation safety and/or efficacy studies); facilitating the systematic monitoring of medications while they are used in clinical practice.
In summary, the European NAFLD Registry is a comprehensive study using standardised data collection practises, clinical monitoring plans and observational protocols to garner the highest quality, large datasets that can be leveraged to better understand and ultimately develop biomarkers across the spectrum of NAFLD severity that can lead to efficient drug discovery and regulatory approval-a key unmet need in NAFLD management. The Registry will facilitate research at scale and pace, with rapid dissemination of research findings to improve patient management and outcomes.

Funding
The European NAFLD Registry is supported by the LITMUS (Liver Investigation: Testing Biomarker Utility in Steatohepatitis) consortium funded by the European Union Innovative Medicines Initiative 2 (IMI2) Joint Undertaking under grant agreement 777377, which receives support from the Horizon 2020 Framework Program of European Union and EFPIA. It has also received support from the EPoS (Elucidating Pathways of Steatohepatitis) consortium funded by the Horizon 2020 Framework Program of the European Union under Grant Agreement 634413, the FLIP consortium funded by the Framework Program 7 of the European Union under grant agreement 241762, and an EASL Registry Grant from the European Association for the Study of the Liver. Additional infrastructure support is provided by Newcastle University, the Newcastle Health Innovation Partners Academic Health Science Centre, the NIHR Newcastle Biomedical Research Centre and NIHR Nottingham Biomedical Research Centre, United Kingdom.

Authors contributions
Study concept and design: Conceptualiziation, funding acquisition and supervision: QMA; project administration and data curation: KW; writing -original draft: TH, KW, QMA; acquisition of data and critical revision of the manuscript for important intellectual content: all authors.

Declaration of Competing Interest
No authors have conflicts of interest relevant to this paper.