Hepatic Steatosis Index (HSI)

HSI explained

The hepatic steatosis index is a screening tool aimed at optimizing the management of non-alcoholic fatty liver disease (NAFLD). It can help clinicians identify candidates for liver ultrasonography and those in need of lifestyle and dietary modifications.

In 2010, Lee et al. have conducted a cross sectional study with 10,724 subjects, 5,362 of which were diagnosed with NAFLD. A derivation and validation cohort have been established.

Each subject underwent a series of laboratory tests, an anthropometric assessment and a questionnaire assessment.

The variables included in the study were: BMI, waist circumference, systolic blood pressure, diastolic blood pressure, serum fasting glucose, haemoglobin A1c, triglycerides, total and HDL cholesterol, AST, ALT, GGT, uric acid and C-reactive protein, amongst others.

Based on the results of multiple logistic regression analysis, the index equation is:

HSI = 8 x ALT/AST + BMI(+ 2 if type 2 diabetes yes, + 2 if female)

Where the BMI is calculated using: body weight (kg)/height squared (m²).

Only the factors found to have the highest predictive value were included in the final equation. In the linear regression model, the index showed a significant correlation with fatty liver disease grade, suggesting that it could potentially reflect more than just the presence of the disease, but also its degree.

The HSI score has been validated in a single-liver disease population and the study excluded patients with HCV, HBV etc.

Index interpretation

Once the equation result is calculated, it is interpreted by comparison to the two cut-off points:

■ HSI values below 30 indicate that NAFLD can be ruled out (with a negative likelihood ratio of up to 0.186).

■ HSI values of 36 and above indicate that NAFLD positive diagnosis is highly likely (with a positive likelihood ratio starting from 6.069).

The negative predictive value (NPV) was 84.3% (82.1–86.2) whilst the positive predictive value (PPV) was 85.9% (83.9–87.6).

The hepatic steatosis index had AUROC of 0.812 (95% CI, 0,801 – 0.824). It was also found that at values below 30, HSI ruled out NAFLD with a sensitivity of 93.1% and at values above 36, HSI detected NAFLD with a specificity of 92.4%.

This score is endorsed by EASL as a screening tool for large-scale studies. The reason is its accuracy and easiness in being calculated with data obtained from medical records.

Hepatic steatosis predictors and their variables

The following table summarizes other tools for NAFLD screening and the data they require:

Original source

Lee JH, Kim D, Kim HJ, et al. Hepatic steatosis index: a simple screening tool reflecting nonalcoholic fatty liver disease. Dig Liver Dis 2010; 42: 503–8.

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. Sviklāne L, Olmane E, Dzērve Z, Kupčs K, Pīrāgs V, Sokolovska J. Fatty liver index and hepatic steatosis index predict non-alcoholic fatty liver disease in type 1 diabetes. J Gastroenterol Hepatol. 2017.

Article reviewed by Dr. Antonio Olveira