Non-Alcoholic Fatty Liver Disease - Liver Fat Score (NAFLD-LFS)

NAFLD-LFS explained

This is a non-invasive prediction tool that reflects the liver fat content in non-alcoholic liver fat disease to help with diagnosis efforts.

Ultrasound is generally the principal method for detecting liver steatosis but it's costly, operator-dependant, or not fully available. Also, ultrasound only detects steatosis if it is present in more than 20-30% of hepatocytes.

Because of this, there is a real interest in developing prediction tools that are both non-invasive, inexpensive and reliant on already collected data.

In the 2009 study by Kotronen et al. the following predicting variables were defined:

■ Existence of metabolic syndrome;

■ Existence of type 2 diabetes;

■ Fasting serum insulin;

■ Aspartate transaminase (AST);

■ Alanine transaminase (ALT);

All these variables are known to have previously been associated with increased liver fat content.

The formula employed after multivariate logistic and linear regression analyses was:

NAFLD-LFS = - 2.89 + 1.18 x Metabolic Syndrome (Yes: 1, No: 0) + 0.45 x Type 2 Diabetes (Yes: 2, No: 0) + 0.15 x Insulin in mU/L + 0.04 x AST in U/L – 0.94 x AST/ALT

The optimal cut-off value for NAFLD was set at -0.640 (86% sensitivity and 71% specificity), meaning that in patients who scored below, NAFLD could be ruled out and in patients who scored above, NAFLD is likely to be diagnosed and they should be referred for liver ultrasonography and other diagnostic methods.

The score had an AUROC curve of 0.87 in the estimation and 0.86 in the validation group.

Hepatic steatosis predictors

Other non-alcoholic fatty liver disease predictor tools include:

■ Fatty Liver Index (FLI);

■ TyG Index (also for insulin resistance);

■ Hepatic Steatosis Index (HSI);

■ ALD/NAFLD Index (ANI).

Original source

Kotronen A, Peltonen M, Hakkarainen A, Sevastianova K, Bergholm R, Johansson LM, Lundbom N, Rissanen A, Ridderstråle M, Groop L, Orho-Melander M, Yki-Järvinen H. Prediction of non-alcoholic fatty liver disease and liver fat using metabolic and genetic factors. Gastroenterology. 2009; 137(3):865-72.

Other references

1. Fedchuk L, Nascimbeni F, Pais R, Charlotte F, Housset C, Ratziu V; LIDO Study Group. Performance and limitations of steatosis biomarkers in patients with nonalcoholic fatty liver disease. Aliment Pharmacol Ther. 2014; 40(10):1209-22.

2. Kahl S, Straßburger K, Nowotny B, Livingstone R, Klüppelholz B, Keßel K, Hwang JH, Giani G, Hoffmann B, Pacini G, Gastaldelli A, Roden M. Comparison of liver fat indices for the diagnosis of hepatic steatosis and insulin resistance. PLoS One. 2014; 9(4):e94059.

Article reviewed by Dr. Antonio Olveira