What are the liver stiffness kPa cut‑off values on transient elastography (FibroScan) for each METAVIR fibrosis stage, and how do they differ in chronic hepatitis B, chronic hepatitis C, and non‑alcoholic fatty liver disease?

Liver Stiffness kPa Cut-off Values on Transient Elastography by METAVIR Stage and Disease Etiology

For chronic hepatitis C, use 7.0 kPa for ≥F2, 10.0 kPa for ≥F3, and 13.0 kPa for F4; for chronic hepatitis B, use 7.0 kPa for ≥F2, 8.0 kPa for ≥F3, and 11.0 kPa for F4; and for NAFLD, use 7.0–8.2 kPa for ≥F2, 8.0–10.0 kPa for ≥F3, and 12.0–13.0 kPa for F4. 1

Chronic Hepatitis C: Most Extensively Validated Cutoffs

The cutoffs for hepatitis C are derived from the largest evidence base and demonstrate the highest diagnostic accuracy across all chronic liver diseases. 1

• ≥F2 (significant fibrosis): 7.0 kPa achieves approximately 75% sensitivity and 84% specificity 1
• ≥F3 (advanced fibrosis): 10.0 kPa provides approximately 87% sensitivity and 88% specificity 1
• F4 (cirrhosis): 13.0 kPa yields approximately 88% sensitivity and 94% specificity 1

These thresholds are based on meta-analysis of 54 studies and represent the most robust evidence available, with an area under the ROC curve of 0.95 for cirrhosis detection. 1 The American Gastroenterological Association recommends a post-SVR cutoff of 9.5 kPa to rule out advanced fibrosis in noncirrhotic patients who have achieved sustained virologic response. 2

Chronic Hepatitis B: Lower Thresholds Than Hepatitis C

Hepatitis B requires modestly lower cutoffs due to different fibrosis patterns and inflammatory activity. 1

• ≥F2 (significant fibrosis): 7.0 kPa with approximately 78% sensitivity and 79% specificity 1
• ≥F3 (advanced fibrosis): 8.0 kPa achieving approximately 87% sensitivity and 83% specificity 1
• F4 (cirrhosis): 11.0 kPa with approximately 81% sensitivity and 87% specificity 1

These cutoffs are derived from 59 studies and demonstrate slightly lower diagnostic accuracy than hepatitis C thresholds. 1 The 2024 WHO guidelines recommend using APRI >0.5 or FibroScan >7.0 kPa to identify significant fibrosis (≥F2) and APRI >1.0 or FibroScan >12.5 kPa to identify cirrhosis for treatment prioritization in resource-limited settings. 2

Non-Alcoholic Fatty Liver Disease: Widest Range and Most Heterogeneity

NAFLD cutoffs show the greatest variability across studies due to metabolic confounders including obesity, diabetes, and steatosis severity. 2

• ≥F2 (significant fibrosis): 7.0–8.2 kPa range, with optimal cutoff at 7.1–7.9 kPa achieving 89% sensitivity and 67% specificity 2
• ≥F3 (advanced fibrosis): 8.0–10.0 kPa range, with optimal cutoff at 8.0–9.9 kPa providing 83% sensitivity and 77% specificity 2
• F4 (cirrhosis): 12.0–13.0 kPa, with optimal cutoff at 12.0–14.1 kPa yielding 55% sensitivity and 88% specificity 2

The American Gastroenterological Association recommends using <8.0 kPa to rule out advanced fibrosis with 93% sensitivity in NAFLD patients. 1 A 2024 meta-analysis of 53 studies demonstrated pooled diagnostic AUCs of 0.90 for the 7.1–7.9 kPa range and 0.87 for the 8.0–9.9 kPa range. 2

Critical caveat: Reported cutoffs for ≥F2 in NAFLD vary widely from 4.8–16.4 kPa across heterogeneous cohorts, reflecting moderate-quality evidence. 1

Key Differences Between Disease Etiologies

Why Cutoffs Differ by Etiology

The pathophysiology of fibrosis deposition varies substantially:

• Hepatitis C produces uniform bridging fibrosis with predictable stiffness progression 1
• Hepatitis B demonstrates patchy fibrosis with variable inflammatory activity, requiring lower thresholds 1
• NAFLD involves metabolic confounders (steatosis, inflammation, congestion) that elevate stiffness independent of fibrosis 2

Alcohol-Related Liver Disease: Highest Cirrhosis Threshold

For completeness, alcohol-related liver disease requires distinct cutoffs:

• ≥F2: 7.8 kPa (80% sensitivity, 91% specificity) 1
• ≥F3: 11.0–12.0 kPa (76–87% sensitivity, 81–92% specificity) 1
• F4: 15.0–18.0 kPa (90–93% sensitivity, 85–86% specificity) 1

The higher cirrhosis threshold (15.0–18.0 kPa versus 11.0–13.0 kPa in viral hepatitis) reflects alcohol's distinct pathophysiology with more pronounced inflammation and congestion. 1

Technical Validity Requirements Apply to All Etiologies

Regardless of disease etiology, FibroScan results are only reliable when meeting all three criteria established by the Korean Association for the Study of the Liver:

• ≥10 successful measurements obtained 2
• Success rate ≥60% 2
• Interquartile range (IQR) <30% of median value when reported in kPa 2

Common Pitfalls When Applying These Cutoffs

Factors That Falsely Elevate Liver Stiffness

Several conditions can overestimate fibrosis stage independent of true fibrosis burden:

• Recent food intake (within 4 hours) increases hepatic blood flow and falsely elevates measurements 2, 1
• Active inflammation with elevated ALT/AST can increase stiffness by 20–30% 2
• Extrahepatic cholestasis elevates stiffness through biliary pressure 2
• Right heart failure causes hepatic congestion and elevated measurements 2
• Acute hepatitis dramatically increases stiffness temporarily 2

Obesity Reduces Diagnostic Accuracy

Failure rates in obese patients (BMI >28 kg/m²) range from 4.3–10.5% in Western populations versus 1.1–3.5% in Asian populations. 1 The XL probe improves success rates but may still underperform compared to MR elastography in severe obesity. 2

MR Elastography: Superior Performance in NAFLD

When transient elastography is technically inadequate or results are discordant with clinical suspicion, MR elastography provides superior diagnostic accuracy in NAFLD:

• ≥F2: 3.2–3.6 kPa (78% sensitivity, 90% specificity) 1
• ≥F3: 3.6–3.9 kPa (82–93% sensitivity, 90–95% specificity) 1
• F4: 6.7 kPa (91% sensitivity, 95% specificity) 1

MRE demonstrates AUROC of 0.92 for ≥F2 and 0.89 for ≥F3 in NAFLD, compared to transient elastography's AUROC of 0.83 for both stages. 1 However, MRE is less accessible and more costly than transient elastography. 1

Algorithmic Approach to Cutoff Selection

Step 1: Identify the primary liver disease etiology (hepatitis C, hepatitis B, NAFLD, or alcohol-related) 1

Step 2: Apply disease-specific cutoffs as outlined above 1

Step 3: Verify technical validity (≥10 measurements, ≥60% success rate, IQR <30%) 2

Step 4: Exclude confounding factors (recent food intake, active inflammation, cholestasis, heart failure) 2

Step 5: If results are discordant with clinical suspicion or technically inadequate, consider MR elastography or liver biopsy 2, 1