Updated S2k Clinical Practice Guideline on Non-alcoholic Fatty Liver Disease (NAFLD) issued by the German Society of Gastroenterology, Digestive and Metabolic Diseases (DGVS) - April 2022 - AWMF Registration No.: 021-025

Obesity and MASLD: Is weight loss the (only) key to treat metabolic liver disease?

Metabolic dysfunction-associated steatotic liver disease (MASLD) closely associates with obesity and type 2 diabetes. Lifestyle intervention and bariatric surgery aiming at substantial weight loss are cornerstones of MASLD treatment by improving histological outcomes and reducing risks of comorbidities. Originally developed as antihyperglycemic drugs, incretin (co-)agonists and SGLT2 inhibitors also reduce steatosis and cardiorenovascular events. Certain incretin agonists effectively improve histological features of MASLD, but not fibrosis. Of note, beneficial effects on MASLD may not necessarily require weight loss. Despite moderate weight gain, one PPARγ agonist improved adipose tissue and MASLD with certain benefit on fibrosis in post-hoc analyses. Likewise, the first THRβ-agonist was recently provisionally approved because of significant improvements of MASLD and fibrosis. We here discuss liver-related and metabolic effects induced by different MASLD treatments and their association with weight loss. Therefore, we compare results from clinical trials on drugs acting via weight loss (incretin (co)agonists, SGLT2 inhibitors) with those exerting no weight loss (pioglitazone; resmetirom). Furthermore, other drugs in development directly targeting hepatic lipid metabolism (lipogenesis inhibitors, FGF21 analogs) are addressed. Although THRβ-agonism may effectively improve hepatic outcomes, MASLD treatment concepts should consider all cardiometabolic risk factors for effective reduction of morbidity and mortality in the affected people.

Thy-1 restricts steatosis and liver fibrosis in steatotic liver disease

BACKGROUND AND AIMS

Steatotic liver disease (SLD) is generally considered to represent a hepatic manifestation of metabolic syndrome and includes a disease spectrum comprising isolated steatosis, metabolic dysfunction-associated steatohepatitis, liver fibrosis and ultimately cirrhosis. A better understanding of the detailed underlying pathogenic mechanisms of this transition is crucial for the design of new and efficient therapeutic interventions. Thymocyte differentiation antigen (Thy-1, also known as CD90) expression on fibroblasts controls central functions relevant to fibrogenesis, including proliferation, apoptosis, cytokine responsiveness, and myofibroblast differentiation.

METHODS

The impact of Thy-1 on the development of SLD and progression to fibrosis was investigated in high-fat diet (HFD)-induced SLD wild-type and Thy-1-deficient mice. In addition, the serum soluble Thy-1 (sThy-1) concentration was analysed in patients with metabolic dysfunction-associated SLD stratified according to steatosis, inflammation, or liver fibrosis using noninvasive markers.

RESULTS

We demonstrated that Thy-1 attenuates the development of fatty liver and the expression of profibrogenic genes in the livers of HFD-induced SLD mice. Mechanistically, Thy-1 directly inhibits the profibrotic activation of nonparenchymal liver cells. In addition, Thy-1 prevents palmitic acid-mediated amplification of the inflammatory response of myeloid cells, which might indirectly contribute to the pronounced development of liver fibrosis in Thy-1-deficient mice. Serum analysis of patients with metabolically associated steatotic liver disease syndrome revealed that sThy-1 expression is correlated with liver fibrosis status, as assessed by liver stiffness, the Fib4 score, and the NAFLD fibrosis score.

CONCLUSION

Our data strongly suggest that Thy-1 may function as a fibrosis-protective factor in mouse and human SLD.

Use of non-invasive diagnostic tools for metabolic dysfunction-associated steatohepatitis: A qualitative exploration of challenges and barriers

BACKGROUND AND AIMS

Non-invasive tests (NITs) are underutilized for diagnosis and risk stratification in metabolic dysfunction-associated steatotic liver disease (MASLD), despite good accuracy. This study aimed to identify challenges and barriers to the use of NITs in clinical practice.

METHODS

We conducted a qualitative exploratory study in Germany, Italy, United Kingdom and United States. Phase 1 participants (primary care physicians, hepatologists, diabetologists, researchers, healthcare administrators, payers and patient advocates; n = 29) were interviewed. Phase 2 participants (experts in MASLD; n = 8) took part in a group discussion to validate and expand on Phase 1 findings. Finally, we triangulated perspectives in a hybrid deductive/inductive thematic analysis.

RESULTS

Four themes hindering the use of NITs emerged: (1) limited knowledge and awareness; (2) unclear referral pathways for patients affected by liver conditions; (3) uncertainty over the value of NITs in monitoring and managing liver diseases; and (4) challenges justifying system-level reimbursement. Through these themes, participants perceived a stigma associated with liver diseases, and primary care physicians generally lacked awareness, adequate knowledge and skills to use recommended NITs. We identified uncertainties over the results of NITs, specifically to guide lifestyle intervention or to identify patients that should be referred to a specialist. Participants indicated an ongoing need for research and development to improve the prognostic value of NITs and communicating their cost-effectiveness to payers.

CONCLUSIONS

This qualitative study suggests that use of NITs for MASLD is limited due to several individual and system-level barriers. Multi-level interventions are likely required to address these barriers.

Liver Stiffness Determined by Transient Elastography Is a Simple and Highly Accurate Predictor for Presence of Liver Cirrhosis in Clinical Routine

INTRODUCTION

Early detection of patients with advanced chronic liver disease is critical for the prevention of complications and inclusion in surveillance programs for hepatocellular carcinoma. In daily clinical care, it remains challenging to differentiate early cirrhosis from lower fibrosis grades without performing a liver biopsy. The aim of the present study was to assess the performance of different non-invasive detection tools to differentiate cirrhosis from lower fibrosis grades.

METHODS

Data of 116 patients (51 male, 65 female) with chronic liver disease of various origins undergoing liver biopsy was analyzed. Routine laboratory values, liver stiffness measurement (LSM) by transient elastography, and histological liver assessment were collected.

RESULTS

Robust and significant correlations with the histological fibrosis stage were identified for LSM (r = 0.65), the FAST score (0.64), the FIB-4 (0.48), serum aspartate aminotransferase (AST) concentration (0.41), NFS (0.33), international normalized ratio (INR; 0.30), methacetin breath test results (-0.40), and serum albumin concentration (-0.29) by spearman rank correlation. Receiver operating characteristic curves were built for these parameters to separate patients with cirrhosis from those with any other fibrosis stage. The highest AUC was achieved by LSM (0.9130), followed by the FAST score (0.8842), the FIB-4 (0.8644), the NFS (0.8227), INR (0.8142), serum albumin (0.7710), and serum AST (0.7620). The most promising clinical applicability would be an LSM value of 12.2 kPa, achieving 95.7% sensitivity and 75.3% specificity.

CONCLUSION

LSM and FAST score seem to be robust non-invasive measurements for liver fibrosis. LSM and FAST scores may have the potential to reliably detect patients with liver cirrhosis in clinical routine settings.

Relevance of GLP-1 receptor agonists or SGLT-2 inhibitors on the recruitment for clinical studies in patients with NAFLD

INTRODUCTION

Guidelines increasingly recommend the use of glucagon-like peptide-1 receptor agonists (GLP-1 RA) or sodium-glucose co-transporter-2 inhibitors (SGLT2i) to prevent cardiovascular and cardiorenal endpoints. Both drugs also show beneficial effects in nonalcoholic fatty liver disease (NAFLD). Preexisting GLP-1 RA and SGLT2i therapies are frequently defined as exclusion criterion in clinical studies to avoid confounding effects. We therefore investigated how this might limit recruitment and design of NAFLD studies.

METHODS

GLP-1 RA and SGLT2i prescriptions were analyzed in NAFLD patients with diabetes mellitus recruited at a tertiary referral center and from the population-based LIFE-Adult-Study. Individuals were stratified according to noninvasive parameters of liver fibrosis based on vibration-controlled transient elastography (VCTE).

RESULTS

97 individuals were recruited at tertiary care and 473 from the LIFE-Adult-Study. VCTE was available in 97/97 and 147/473 cases.GLP-1 RA or SGLT2i were used in 11.9% of the population-based cohort (LSM < 8 kPa), but in 32.0% with LSM ≥ 8 kPa. In the tertiary clinic, it was 30.9% overall, independent of LSM, and 36.8% in patients with medium and high risk for fibrotic NASH (FAST score > 0.35). At baseline, 3.1% of the patients in tertiary care were taking GLP-1 RA and 4.1% SGLT2i. Four years later, the numbers had increased to 15.5% and 21.6%.

CONCLUSION

GLP-1 RA and SGLT2i are frequently and increasingly prescribed. In candidates for liver biopsy for NASH studies (VCTE ≥ 8 kPa) the use of them exceeds 30%, which needs careful consideration when designing NASH trials.

Non-invasive assessment of steatohepatitis indicates increased risk of coronary artery disease

INTRODUCTION

Fatty liver diseases (FLD), especially defined as metabolic dysfunction-associated FLD (MAFLD), is of growing importance for patients and health-care providers. Extrahepatic comorbidities, predominantly coronary artery disease (CAD), contribute to excess morbidity and mortality in FLD. Although the association of FLD and CAD is well known, underlying pathophysiological links are not fully understood. Non-invasive means of liver diagnostic enable a fast and thorough characterization of FLD. We therefore assessed the severity of FLD in a cohort of patients at risk of CAD.

METHODS

Patients scheduled for coronary angiography were characterized by anthropometry, serum-based indices of liver fibrosis (NFS, FIB4), abdominal ultrasound and vibration controlled transient elastography (VCTE) including controlled attenuation parameter (CAP) and the Fibroscan-AST (FAST) score. Patients were stratified according to indication of therapeutic coronary intervention.

RESULTS

120 patients were recruited, MAFLD was found in 41%, while advanced fibrosis or cirrhosis were present in only 5%. Coronary vascular intervention was indicated in 42% (n = 50). Severity of steatosis assessed by CAP and risk of fibrosis defined by elevated liver stiffness (VCTE>8 kPa) and fibrosis indices were associated with the need for coronary intervention. FAST score, a marker of fibrotic steatohepatitis, was elevated in the intervention group (0.22 vs. 0.12, p<0.001). Multivariate regression analysis revealed FAST score as strongest predictor of CAD (OR 2.3 95%, CI 1.40-2.96).

DISCUSSION

MAFLD is a frequent comorbidity in patients at CAD risk, but advanced liver disease has a low prevalence in patients undergoing elective coronary angiography. Therefore, a routine VCTE-based screening for FLD cannot be recommended in cardiac patients. The association of indicators of steatohepatitis with advanced CAD points to inflammatory processes as a conjoint mechanism of both diseases.

The Association between Liver Enzymes and Mortality Stratified by Non-Alcoholic Fatty Liver Disease: An Analysis of NHANES III

Associations between liver enzymes or De Ritis ratio (DRR; aspartate aminotransferase (AST)/alanine aminotransferase (ALT)) and mortality stratified by non-alcoholic fatty liver disease (NAFLD), which have rarely been analyzed in previous studies, were investigated using the National Health and Nutrition Examination Survey (NHANES) III (1988-1994). Participants without risk factors for liver diseases other than NAFLD were linked with National Death Index records through 2019 (n = 11,385) and divided into two cohorts with or without NAFLD, based on ultrasound examination. Liver enzyme concentrations were categorized into sex-specific deciles and subsequently grouped (AST and ALT: 1-3, 4-9, 10; gamma glutamyltransferase (GGT): 1-8, 9-10). DRR was categorized into tertiles. Cox proportional hazards regression models adjusted for confounders were fitted to estimate associations with mortality. Compared with low levels, high GGT and DRR in participants with and without NAFLD had significantly higher hazard ratios for all-cause mortality. Compared with intermediate concentrations, low ALT showed higher all-cause mortality in participants with and without NAFLD, whereas low AST had higher HR in participants without NAFLD and high AST in those with NAFLD. Mortality was associated with liver enzymes or DRR in participants both with and without NAFLD, indicating that the relationship is not mediated solely by hepatocellular damage.

[Elevated liver values caused by nonalcoholic steatohepatitis (NASH)]

Non-alcoholic steatohepatitis (NASH) is the progressive entity of non-alcoholic fatty liver disease (NAFLD) and characterised by increased inflammatory activity, potentially resulting in liver fibrosis and ultimately cirrhosis. NASH activity and hepatic fibrosis are the prognosis determinating risk factors - rational stepwise diagnostic approaches are urgently needed as therapeutic options beyond lifestyle modifications are limited.