{ "id": "epqwxgekvy", "slug": "nafld-fibrosis-score", "title": "NAFLD fibrosis score", "updated": "2026-10-25", "topic_path": [ { "id": "life", "label": "Life and health", "api_url": "https://www.edgepedia.org/api/v1/topics/life" }, { "id": "life.health", "label": "Human health and medicine", "api_url": "https://www.edgepedia.org/api/v1/topics/life.health" }, { "id": "life.health.clinical", "label": "Clinical assessment and procedures", "api_url": "https://www.edgepedia.org/api/v1/topics/life.health.clinical" }, { "id": "life.health.clinical.clinical-diagnostics", "label": "Diagnosis and clinical assessment", "api_url": "https://www.edgepedia.org/api/v1/topics/life.health.clinical.clinical-diagnostics" }, { "id": "life.health.clinical.clinical-diagnostics.diagnostic-classification-and-scoring", "label": "Diagnostic classification and scoring", "api_url": "https://www.edgepedia.org/api/v1/topics/life.health.clinical.clinical-diagnostics.diagnostic-classification-and-scoring" }, { "id": "life.health.clinical.clinical-diagnostics.diagnostic-classification-and-scoring.nutrition-and-frailty-screening", "label": "Nutrition and frailty screening", "api_url": "https://www.edgepedia.org/api/v1/topics/life.health.clinical.clinical-diagnostics.diagnostic-classification-and-scoring.nutrition-and-frailty-screening" } ], "geo": [ { "id": "geo.nongeo.t2001.life.health.clinical.clinical-diagnostics.diagnostic-classification-and-scoring", "label": "Non-geographic · 2001 to 2020: Diagnostic classification and scoring", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t2001.life.health.clinical.clinical-diagnostics.diagnostic-classification-and-scoring", "path": [ { "id": "geo.nongeo", "label": "Non-geographic", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo" }, { "id": "geo.nongeo.t2001", "label": "Non-geographic · 2001 to 2020", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t2001" }, { "id": "geo.nongeo.t2001.life", "label": "Life and health", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t2001.life" }, { "id": "geo.nongeo.t2001.life.health", "label": "Human health and medicine", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t2001.life.health" }, { "id": "geo.nongeo.t2001.life.health.clinical", "label": "Clinical assessment and procedures", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t2001.life.health.clinical" }, { "id": "geo.nongeo.t2001.life.health.clinical.clinical-diagnostics", "label": "Diagnosis and clinical assessment", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t2001.life.health.clinical.clinical-diagnostics" }, { "id": "geo.nongeo.t2001.life.health.clinical.clinical-diagnostics.diagnostic-classification-and-scoring", "label": "Diagnostic classification and scoring", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t2001.life.health.clinical.clinical-diagnostics.diagnostic-classification-and-scoring" } ] } ], "excerpt": "The NAFLD fibrosis score (NFS) is a formula combining six routine laboratory results and patient characteristics to estimate advanced liver fibrosis in nonalcoholic fatty liver disease and guide biopsy decisions.", "snippet": "The NAFLD fibrosis score (NFS) is a formula combining six routine laboratory results and patient characteristics to estimate advanced liver fibrosis in nonalcoholic fatty liver disease and guide biopsy decisions.", "node": "life.health.clinical.clinical-diagnostics.diagnostic-classification-and-scoring.nutrition-and-frailty-screening", "markdown": "# NAFLD fibrosis score\n\nThe NAFLD fibrosis score (NFS) is a formula that combines six routine laboratory results and patient characteristics to estimate whether a patient with nonalcoholic fatty liver disease (NAFLD) has advanced liver fibrosis, and to decide who needs referral, further testing, or liver biopsy.[1](https://pubmed.ncbi.nlm.nih.gov/17393509) It was built to identify patients at increased risk of cirrhosis, liver-related complications, or death without requiring a biopsy,[2](https://pmc.ncbi.nlm.nih.gov/articles/PMC10550044/) and a high score is associated with increased mortality (pooled relative risk 4.54, 95% CI 1.85–11.17, across five cohort studies of 5,033 patients).[3](https://www.em-consulte.com/article/1182838/the-utility-of-nafld-fibrosis-score-for-prediction) Guidelines use it as a first-line, non-patented blood test for ruling out advanced fibrosis, with elastography (imaging that measures liver stiffness to gauge scarring) as the second step.[4](https://easl.eu/wp-content/uploads/2021/06/EASL-Clinical-Practice-Guidelines-on-non-invasive-tests-for-evaluation-of-liver-disease-severity-and-prognosis-%E2%80%93-2021-update.pdf)\n\n| Key fact | Detail |\n|---|---|\n| Purpose | Estimates presence of advanced fibrosis (stage F3–F4) in NAFLD to support biopsy and referral decisions[1](https://pubmed.ncbi.nlm.nih.gov/17393509) |\n| Variables | Age, BMI, impaired fasting glucose/diabetes, AST/ALT ratio, platelet count, albumin[1](https://pubmed.ncbi.nlm.nih.gov/17393509) |\n| Cutoffs | < −1.455 rules out; > 0.676 rules in advanced fibrosis[1](https://pubmed.ncbi.nlm.nih.gov/17393509) |\n| Original accuracy | AUROC 0.88 (estimation) and 0.82 (validation); NPV 93%/88%, PPV 90%/82%[1](https://pubmed.ncbi.nlm.nih.gov/17393509) |\n| Biopsy sparing | Would have avoided biopsy in 549 of 733 patients (75%), correctly in 90%[1](https://pubmed.ncbi.nlm.nih.gov/17393509) |\n| Gray zone | Roughly one-third of patients fall between the cutoffs (reported rates of 33.5% to 39%)[4](https://easl.eu/wp-content/uploads/2021/06/EASL-Clinical-Practice-Guidelines-on-non-invasive-tests-for-evaluation-of-liver-disease-severity-and-prognosis-%E2%80%93-2021-update.pdf) • [5](https://socgastro.org.br/novo/wp-content/uploads/2025/01/AASLD-Practice-Guideline-on-blood-based-noninvasive-liver-disease-assessment-of-hepatic-fibrosis-and-steatosis.pdf) • [6](https://link.springer.com/article/10.1007/s13679-024-00574-z) |\n| Guideline role | Recommended first-tier serum test, followed by elastography in indeterminate or high-risk cases[7](https://pmc.ncbi.nlm.nih.gov/articles/PMC11299976/) |\n\n## How it works\n\nThe score is a weighted linear combination of variables that independently indicated advanced fibrosis on multivariate analysis in the derivation cohort: age, hyperglycemia, body mass index, platelet count, albumin, and the [AST/ALT ratio](https://www.edgepedia.org/ast-alt-ratio).[1](https://pubmed.ncbi.nlm.nih.gov/17393509) The formula is[1](https://pubmed.ncbi.nlm.nih.gov/17393509)\n\n\\[ \\mathrm{NFS} = -1.675 + 0.037 \\cdot \\text{age (years)} + 0.094 \\cdot \\text{BMI (kg/m}^2\\text{)} + 1.13 \\cdot \\text{IFG/diabetes (yes = 1, no = 0)} + 0.99 \\cdot \\frac{\\text{AST}}{\\text{ALT}} - 0.013 \\cdot \\text{platelet} (\\times 10^{9}/\\text{l}) - 0.66 \\cdot \\text{albumin (g/dl)} \\]\n\nThe direction of each term reflects the biology of progressive fibrosis: older age, higher BMI, diabetes, and a higher AST/ALT ratio raise the score, while higher platelet counts and albumin lower it.[1](https://pubmed.ncbi.nlm.nih.gov/17393509) Two cutoffs are applied. A score below −1.455 excludes advanced fibrosis with a negative predictive value of 93% in the estimation group and 88% in the validation group; a score above 0.676 diagnoses it with a positive predictive value of 90% and 82% respectively.[1](https://pubmed.ncbi.nlm.nih.gov/17393509) Scores between the two cutoffs are indeterminate.\n\n## How it is done\n\nCalculation requires only a routine clinical visit: age, height and weight for BMI, diabetes or impaired fasting glucose status, and a standard blood panel providing AST, ALT, platelet count, and albumin.[1](https://pubmed.ncbi.nlm.nih.gov/17393509) The result is interpreted against the two cutoffs. A low score identifies a patient in whom advanced fibrosis can be excluded and biopsy avoided; a high score flags advanced fibrosis and the need for specialist care; an intermediate score prompts a second-line test, typically liver stiffness measurement by elastography.[4](https://easl.eu/wp-content/uploads/2021/06/EASL-Clinical-Practice-Guidelines-on-non-invasive-tests-for-evaluation-of-liver-disease-severity-and-prognosis-%E2%80%93-2021-update.pdf) EASL recommends that non-invasive tests be used for ruling out rather than diagnosing advanced fibrosis in low-prevalence populations, preferentially in patients with metabolic risk factors or harmful alcohol use.[4](https://easl.eu/wp-content/uploads/2021/06/EASL-Clinical-Practice-Guidelines-on-non-invasive-tests-for-evaluation-of-liver-disease-severity-and-prognosis-%E2%80%93-2021-update.pdf)\n\n## Origin\n\nThe score was described in *Hepatology*, using 733 patients with biopsy-confirmed NAFLD from four centers: Mayo Clinic Rochester (n = 356), Newcastle UK (n = 158), Sydney Australia (n = 123), and Italy (n = 96), biopsied between 2000 and 2003. The cohort was split into an estimation group (n = 480) and a validation group (n = 253).[1](https://pubmed.ncbi.nlm.nih.gov/17393509) The authors stated that the results needed validation in independent populations, and in children, adolescents, non-Caucasian patients, and patients with persistently normal aminotransferases.[1](https://pubmed.ncbi.nlm.nih.gov/17393509)\n\n## Variants\n\nFIB-4 uses only age, AST, ALT, and platelet count; a FIB-4 below 1.3 excludes advanced fibrosis with a negative predictive value of 95%, and above 2.67 indicates it with 70% positive predictive value, although cutoffs vary across validation studies, including a rule-in cutoff of 3.25 in some schemes.[2](https://pmc.ncbi.nlm.nih.gov/articles/PMC10550044/) • [4](https://easl.eu/wp-content/uploads/2021/06/EASL-Clinical-Practice-Guidelines-on-non-invasive-tests-for-evaluation-of-liver-disease-severity-and-prognosis-%E2%80%93-2021-update.pdf) In meta-analyses the two scores perform similarly: summary AUROCs of 0.84 for both NFS and FIB-4 in one analysis,[8](https://europepmc.org/article/MED/28586172) and pooled sensitivities of 70% (NFS) versus 69% (FIB-4) with specificities of 61% versus 64% in another.[9](https://www.gutnliver.org/journal/view.html?doi=10.5009%2Fgnl210391) EASL lists NFS below −1.455 alongside FIB-4 below 1.3, liver stiffness below 8 kPa, ELF below 9.8, FibroMeter below 0.45, and [FibroTest](https://www.edgepedia.org/fibrotest) below 0.48 as thresholds that can exclude advanced fibrosis.[4](https://easl.eu/wp-content/uploads/2021/06/EASL-Clinical-Practice-Guidelines-on-non-invasive-tests-for-evaluation-of-liver-disease-severity-and-prognosis-%E2%80%93-2021-update.pdf)\n\n## Applications\n\nGuidelines use the score as a first-tier serum test in community and specialist settings, followed by liver stiffness measurement in patients with indeterminate or high results.[7](https://pmc.ncbi.nlm.nih.gov/articles/PMC11299976/) About one-third of patients fall between the two cutoffs and receive an indeterminate result,[4](https://easl.eu/wp-content/uploads/2021/06/EASL-Clinical-Practice-Guidelines-on-non-invasive-tests-for-evaluation-of-liver-disease-severity-and-prognosis-%E2%80%93-2021-update.pdf) with reported rates of 33.5% (95% CI 25.6–44.4) in the AASLD review[5](https://socgastro.org.br/novo/wp-content/uploads/2025/01/AASLD-Practice-Guideline-on-blood-based-noninvasive-liver-disease-assessment-of-hepatic-fibrosis-and-steatosis.pdf) and 39% in an individual patient data meta-analysis of 3,248 patients.[5](https://socgastro.org.br/novo/wp-content/uploads/2025/01/AASLD-Practice-Guideline-on-blood-based-noninvasive-liver-disease-assessment-of-hepatic-fibrosis-and-steatosis.pdf) For these patients, guidelines support a two-tier strategy: an inexpensive serum score (FIB-4 or NFS) in the community, followed by liver stiffness measurement in those with indeterminate or high results.[10](https://gut.bmj.com/content/71/5/1006) In that meta-analysis, sequential FIB-4 (<1.3; ≥2.67) followed by transient elastography (<8.0; ≥10.0 kPa) achieved sensitivity 66% (63–68) and specificity 86% (84–87) with 33% indeterminate results.[10](https://gut.bmj.com/content/71/5/1006) Sequential testing reduces biopsy need without compromising sensitivity and specificity, although using multiple tests can increase misclassification.[2](https://pmc.ncbi.nlm.nih.gov/articles/PMC10550044/)\n\n## Limitations and alternatives\n\nPublished accuracy varies with the cohort. In the original study the AUROC was 0.88 (95% CI 0.85–0.92) in the estimation group and 0.82 in the validation group.[1](https://pubmed.ncbi.nlm.nih.gov/17393509) A meta-analysis of 36 studies in 9,074 patients reported AUROCs of 0.78 for NFS and 0.80 for FIB-4, with negative predictive values above 90% for excluding advanced fibrosis but positive predictive values below 70%.[4](https://easl.eu/wp-content/uploads/2021/06/EASL-Clinical-Practice-Guidelines-on-non-invasive-tests-for-evaluation-of-liver-disease-severity-and-prognosis-%E2%80%93-2021-update.pdf) [Performance](https://www.edgepedia.org/performance) is lower in population-based and non-Western samples: in NHANES 2017–2018 participants (n = 2,622) the AUROC was 0.679, and in an Asian biopsy-proven cohort (n = 293) it was 0.699, with optimal cutoffs lower than the original values.[11](https://www.xiahepublishing.com/2310-8819/JCTH-2021-00311) The score's main limitations are its dependence on age and BMI, which can produce high false-positive rates, and inaccuracy in patients with altered platelet counts from other causes, such as asplenia or a transjugular intrahepatic [portosystemic shunt](https://www.edgepedia.org/portosystemic-shunt).[6](https://link.springer.com/article/10.1007/s13679-024-00574-z) Both NFS and FIB-4 perform poorly in individuals younger than 35 years,[7](https://pmc.ncbi.nlm.nih.gov/articles/PMC11299976/) and accuracy is lower in alcohol-associated liver disease (AUROC approximately 0.65–0.75) because of alcohol-related transaminase variability and thrombocytopenia.[12](https://link.springer.com/article/10.1007/s11901-026-00727-9) In 2023, a multisociety nomenclature change replaced NAFLD with metabolic dysfunction-associated steatotic liver disease (MASLD), defined by steatosis plus at least one of five cardiometabolic risk factors, and introduced MetALD for patients consuming greater amounts of alcohol; large cohorts show more than 98% overlap between NAFLD/NASH and MASLD/MASH criteria, and the score's rule-out performance carries over.[5](https://socgastro.org.br/novo/wp-content/uploads/2025/01/AASLD-Practice-Guideline-on-blood-based-noninvasive-liver-disease-assessment-of-hepatic-fibrosis-and-steatosis.pdf) • [13](https://www.aasld.org/sites/default/files/2024-01/SLD-597%20AASLD%202023%20MASLD%20Decision%20Tree%20Digital%20%28sm%291.8.pdf) Newer tools include machine-learning-derived indices such as FIB-6, which cannot be written as closed formulae but may have improved diagnostic value,[7](https://pmc.ncbi.nlm.nih.gov/articles/PMC11299976/) and indices such as FIB-9, FIB-11, and FIB-12, which reach AUROCs of approximately 0.90–0.92 in MASLD with reduced indeterminate zones, though validation in alcohol-predominant phenotypes remains limited.[12](https://link.springer.com/article/10.1007/s11901-026-00727-9) Imaging tests outperform serum scores for advanced fibrosis: summary AUROCs were 0.88 for FibroScan M probe, 0.95 for shear-wave elastography, and 0.96 for magnetic resonance elastography, compared with 0.84 for NFS, 0.77 for APRI, and 0.76 for BARD.[8](https://europepmc.org/article/MED/28586172)\n\n## References\n\n1. [The NAFLD fibrosis score: a noninvasive system that identifies liver fibrosis in patients with NAFLD (Angulo et al., Hepatology 2007), PubMed record with full-text excerpts](https://pubmed.ncbi.nlm.nih.gov/17393509)\n2. [Noninvasive tests in the evaluation of nonalcoholic fatty liver disease: A review (2023)](https://pmc.ncbi.nlm.nih.gov/articles/PMC10550044/)\n3. [The utility of NAFLD fibrosis score for prediction of mortality among patients with nonalcoholic fatty liver disease: A systematic review and meta-analysis of cohort studies](https://www.em-consulte.com/article/1182838/the-utility-of-nafld-fibrosis-score-for-prediction)\n4. [EASL Clinical Practice Guidelines on non-invasive tests for evaluation of liver disease severity and prognosis – 2021 update](https://easl.eu/wp-content/uploads/2021/06/EASL-Clinical-Practice-Guidelines-on-non-invasive-tests-for-evaluation-of-liver-disease-severity-and-prognosis-%E2%80%93-2021-update.pdf)\n5. [AASLD Practice Guideline on blood-based noninvasive liver disease assessment of hepatic fibrosis and steatosis](https://socgastro.org.br/novo/wp-content/uploads/2025/01/AASLD-Practice-Guideline-on-blood-based-noninvasive-liver-disease-assessment-of-hepatic-fibrosis-and-steatosis.pdf)\n6. [Non-invasive Scores and Serum Biomarkers for Fatty Liver in the Era of MASLD: A Comprehensive Review From NAFLD to MAFLD and MASLD (Current Obesity Reports, 2024)](https://link.springer.com/article/10.1007/s13679-024-00574-z)\n7. [EASL-EASD-EASO Clinical Practice Guidelines on the Management of Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD)](https://pmc.ncbi.nlm.nih.gov/articles/PMC11299976/)\n8. [Comparison of laboratory tests, ultrasound, or magnetic resonance elastography to detect fibrosis in patients with nonalcoholic fatty liver disease: A meta-analysis (64 articles, 13,046 subjects)](https://europepmc.org/article/MED/28586172)\n9. [Accuracy of Noninvasive Scoring Systems in Assessing Liver Fibrosis in Patients with Nonalcoholic Fatty Liver Disease: A Systematic Review and Meta-Analysis (Gut and Liver)](https://www.gutnliver.org/journal/view.html?doi=10.5009%2Fgnl210391)\n10. [Diagnostic accuracy of non-invasive tests for advanced fibrosis in patients with NAFLD: an individual patient data meta-analysis (Gut)](https://gut.bmj.com/content/71/5/1006)\n11. [Validation of Non-invasive Fibrosis Scores for Predicting Advanced Fibrosis in Metabolic-associated Fatty Liver Disease](https://www.xiahepublishing.com/2310-8819/JCTH-2021-00311)\n12. [Steatotic Liver Disease: Does Existing Non-Invasive Markers Fit the Updated Nomenclature? (Current Hepatology Reports)](https://link.springer.com/article/10.1007/s11901-026-00727-9)\n13. [AASLD 2023 MASLD Decision Tree (No More NAFLD)](https://www.aasld.org/sites/default/files/2024-01/SLD-597%20AASLD%202023%20MASLD%20Decision%20Tree%20Digital%20%28sm%291.8.pdf)\n\n---\n*Topic: Encyclopedia › Life and health › Human health and medicine › Clinical assessment and procedures › Diagnosis and clinical assessment › Diagnostic classification and scoring › Nutrition and frailty screening*\n\n*Initially written Sep 29, 2026 · Reviewed: Sep 30, 2026 · Edited: Sep 30, 2026; Oct 25, 2026 · Last review: Sep 30, 2026*\n\n*Copyright 2026 EdgeChat AI, a subsidiary of Biostate AI.*\n\nLicense: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license\n", "same_as": [], "url": "https://www.edgepedia.org/nafld-fibrosis-score", "markdown_url": "https://www.edgepedia.org/nafld-fibrosis-score.md", "license": { "name": "Edgepedia Community License 1.0", "url": "https://www.edgepedia.org/edgepedia/license", "summary": "Free with credit, commercial use included. AI training is open to everyone. For other uses, organizations over USD 100M in revenue or 100M monthly users license separately.", "spdx": "LicenseRef-Edgepedia-Community-1.0" }, "credit": "\"NAFLD fibrosis score\", Edgepedia (EdgeChat), https://www.edgepedia.org/nafld-fibrosis-score. Edgepedia Community License 1.0.", "credit_md": "\"[NAFLD fibrosis score](https://www.edgepedia.org/nafld-fibrosis-score)\", Edgepedia (EdgeChat), [https://www.edgepedia.org/nafld-fibrosis-score](https://www.edgepedia.org/nafld-fibrosis-score). [Edgepedia Community License 1.0](https://www.edgepedia.org/edgepedia/license).", "credit_html": "\"NAFLD fibrosis score\", Edgepedia (EdgeChat), https://www.edgepedia.org/nafld-fibrosis-score. Edgepedia Community License 1.0.", "speakable": "The NAFLD fibrosis score is a formula combining six routine laboratory results and patient characteristics to estimate advanced liver fibrosis in nonalcoholic fatty liver disease and guide biopsy decisions." }