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Key Clinical Summary: Non-Invasive Monitoring Techniques for Patients with MASH

This is a micro-learning module summary of Dr David Chascsa's MASH Academy session which you can find here.

Before participating please read our CME and disclosure information which can be found here.

The MASH Academy was supported by an independent medical education grant from Novo Nordisk.

Introduction:

This summary provides an overview of non-invasive tests used in the diagnosis, staging, and monitoring of Metabolic Dysfunction-Associated Steatohepatitis (MASH). With increasing prevalence of steatotic liver disease, it is important to differentiate it from alcohol-related liver disease, and there is a need for accurate assessment of fibrosis to guide management.

Steatotic Liver Disease and MASLD:

  • Steatotic liver disease is defined histologically as liver fat content greater than 5% of liver weight or when greater than 5% of hepatocytes contain fat globules.
  • MASLD (Metabolic Dysfunction-Associated Steatotic Liver Disease) is a spectrum of conditions where hepatic steatosis is present along with one or more metabolic risk factors, including:
  • Elevated BMI (with ethnicity-specific considerations)
  • Elevated HbA1c or markers of diabetes
  • Hypertension
  • Hypertriglyceridemia or low HDL

Epidemiology and Significance:

  • Steatotic liver disease is a major global health concern, affecting up to 25% of the world's population.
  • In the United States, 2-14% of adults may have MASH, putting millions at risk for advanced fibrosis and liver transplantation.
  • The prevalence of MASLD is increasing by approximately 1% per year.
  • MASH cirrhosis is becoming a leading indication for liver transplantation, particularly in women and older adults.

Diagnosis of Fatty Liver:

  • Liver blood tests (liver injury tests) are not sufficient to rule in or rule out MASLD or MASH.
  • Imaging can aid in the MASLD diagnosis.
  • Ultrasound:
  • A good initial screening test due to low cost and wide availability.
  • Sensitive and specific for moderate to severe steatosis.
  • May miss steatosis with liver fat content < 20%.
  • Unenhanced CT Scan:
  • Can aid in diagnosis by comparing liver density to spleen density (hypodense liver suggests fatty infiltration).
  • Contrast enhancement affects liver and spleen densities.
  • MRI-PDFF (Magnetic Resonance Imaging Proton Density Fat Fraction):
  • The gold standard for non-invasive assessment of fatty liver.
  • Accurate, precise, and reproducible.
  • Allows for global liver assessment.
  • Can be influenced by fibrosis and iron overload.
  • Highly sensitive (96%) and specific (100%) for detecting > 5% liver fat.

Staging Liver Fibrosis:

  • Accurate staging of fibrosis is crucial as it has the most significant clinical implications for liver-related events, transplant, and death.
  • Fibrosis progression can occur even without significant inflammation.
  • MASLD progresses approximately one fibrosis stage every 14 years, while MASH progresses faster (one stage every 7 years).

Non-Invasive Fibrosis Tests:

  • Blood-Based Tests:

  • Easy to implement in clinical practice and cost-effective.

  • Examples: FIB-4 score and NAFLD fibrosis score.

  • FIB-4 Score:

  • Calculated using AST, ALT, platelet count, and age.

  • FIB-4 < 1.3 generally excludes advanced fibrosis (< 2.0 in patients > 65 years).

  • May underestimate fibrosis in patients < 35 years and has decreased accuracy in patients > 65 years.

  • ELF (Enhanced Liver Fibrosis) Score:

  • Measures markers of matrix turnover.

  • Excellent for diagnosing advanced fibrosis

  • Caveats: Can be affected by extrahepatic inflammatory or fibrotic conditions and is relatively expensive.

  • Imaging-Based Tests:

  • Ultrasound-Based Elastography:

  • Includes VCTE (Vibration-Controlled Transient Elastography, FibroScan), ARFI, point shear wave elastography, and 2D shear wave elastography.

  • Attractive as point-of-care testing when combined with ultrasound.

  • VCTE is most commonly used in clinical practice guidelines and for assessing portal hypertension risk.

  • VCTE is highly accurate for detecting advanced fibrosis and cirrhosis

  • MRI:

  • Offers the most accurate non-invasive assessment of fibrosis.

  • Provides a comprehensive assessment of the entire liver.

  • Excellent AUROCs for detecting F2, F3, and F4.

  • Limitations: Availability and cost (especially when combined with contrast-enhanced MRI).

  • Combination Scores:

  • Examples: Agile 3+, Agile 4, MIFIB, FAST, and SAFE scores.

  • Agile 3+ includes AST/ALT ratio, platelet count, diabetes status, sex, age, and liver stiffness.

  • SAFE score is based on clinical risk factors and routine lab testing.

Clinical Algorithm for Evaluation and Risk Stratification:

  • Identify At-Risk Patients:
  • Type 2 diabetes
  • Metabolic syndrome
  • Obesity
  • Moderate alcohol use
  • Family history of fatty liver disease
  • Elevated liver injury tests
  • Steatosis on imaging
  • Initial Evaluation:
  • Routine blood tests (CBC, liver injury tests)
  • Calculate FIB-4 score
  • Risk Stratification and Management:
  • Low Risk (FIB-4 < 1.3): Managed by primary care with periodic FIB-4 assessment.
  • High Risk (FIB-4 > 3.25): Refer to hepatology for further evaluation (e.g., MRE), liver cancer screening, and management.
  • Indeterminate Risk (FIB-4 1.3-3.25): Second-line test (VCTE or ELF score) is needed. MRE may be cost-effective in patients with FIB-4 > 2.66. Hepatology consultation may then be needed for surveillance and treatment planning.
  • Additional Considerations:
  • Assess alcohol use.
  • Screen for hepatitis C.
  • Consider testing for other liver diseases if clinically indicated.

Monitoring Disease Progression and Treatment Response:

  • Serial monitoring is crucial as MASLD can progress.
  • Liver injury tests can be helpful, especially in monitoring response to interventions like dietary changes.
  • Fibrosis progression is a key concern, and non-invasive tests are used for surveillance.
  • FIB-4:
  • Serial FIB-4 measurements can predict outcomes.
  • Changes in FIB-4 score correlate with the risk of severe liver disease.
  • However, FIB-4 is not perfect, as events can occur even in patients with consistently low scores.
  • Liver Stiffness Measurement (VCTE/MRE):
  • Baseline liver stiffness predicts adverse outcomes.
  • Changes in liver stiffness correlate with hepatic decompensation, mortality, and liver cancer risk.

Conclusion:

Non-invasive tests are essential tools for diagnosing, staging, and monitoring patients with MASLD. They help assess fibrosis risk, predict outcomes, and evaluate treatment response. A thorough understanding of these tests and their limitations is crucial for effective clinical management.