Liver, Pancreas and Biliary Tract
Hepatic steatosis index: A simple screening tool reflecting nonalcoholic fatty liver disease

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Abstract

Background/Aims

To optimize management of nonalcoholic fatty liver disease (NAFLD), a simple screening tool is necessary. In this study, we aimed to devise a simple index of NAFLD.

Study

A cross-sectional study with 10,724 health check-up subjects (5362 cases with NAFLD versus age- and sex-matched controls) was conducted. Study subjects were randomly assigned to a derivation cohort or a validation cohort.

Results

Multivariate analysis indicated that high serum alanine aminotransferase (ALT) to serum aspartate aminotransferase (AST) ratio, high body mass index (BMI), and diabetes mellitus were independent risk factors of NAFLD (all P < 0.001). Using these variables, a formula was derived by a logistic regression model: hepatic steatosis index (HSI) = 8 × (ALT/AST ratio) + BMI (+2, if female; +2, if diabetes mellitus). HSI had an area under receiver-operating curve of 0.812 (95% confidence interval, 0.801–0.824). At values of <30.0 or >36.0, HSI ruled out NAFLD with a sensitivity of 93.1%, or detected NAFLD with a specificity of 92.4%, respectively. Of 2692 subjects with HSI <30.0 or >36.0 in the derivation cohort, 2305 (85.6%) were correctly classified. HSI was validated in the subsequent validation cohort.

Conclusion

HSI is a simple, efficient screening tool for NAFLD that may be utilized for selecting individuals for liver ultrasonography and for determining the need for lifestyle modifications.

Introduction

Nonalcoholic fatty liver disease (NAFLD) is believed to be a feature of metabolic syndrome because it is closely associated with visceral obesity, dyslipidaemia, insulin resistance, and type 2 diabetes mellitus (DM) [1]. Due to the increased prevalence of obesity, about 30% of the adult population now has NAFLD in the United States [2]. In Korea, the prevalence of NAFLD has been reported to be 16.1–27.2% and continues to increase due to the adoption of a Westernized lifestyle [3], [4], [5]. This high prevalence of NAFLD is probably problematic because patients with NAFLD show higher all-cause mortality and increased risks for liver-related death and cardiovascular disease [6], [7]. However, the screening of asymptomatic individuals using imaging modalities, such as ultrasonography (US) and computed tomography (CT), does not appear to be cost-effective because such studies are expensive for mass screening. Therefore, a simple, noninvasive test is required to identify patients at high risk of NAFLD and to establish an appropriate NAFLD screening programme. In this study, we aimed to derive a simple index based on standard laboratory tests and anthropometric parameters that can be used to determine the presence of NAFLD. In addition, we sought to validate this index in asymptomatic subjects.

Section snippets

Subjects

We performed a cross-sectional case–control study. A total of 21,130 adults who visited Seoul National University Hospital Gangnam Healthcare Center, Seoul, Korea for a routine health check-up between 1 January 2006 and 31 December 2006 participated in this study. NAFLD was defined as the presence of fatty liver disease by US in the absence of a potential cause of chronic liver disease, namely, (i) seropositivity for hepatitis B virus surface antigen (HBsAg) or anti-hepatitis C virus antibody

Baseline characteristics

Of the 21,130 participants, 3591 participants with at least one potential cause of chronic liver disease were excluded: 975 with hepatitis B, 242 with hepatitis C, 1690 with excessive alcohol consumption (>20 g/day), 593 taking medications known to produce fatty liver (steroids, oestrogens, tamoxifen, valproate, diltiazem, amiodarone, methotrexate, and so on) and 91 participants with other causes (Wilson's disease, haemochromatosis, primary biliary cirrhosis, autoimmune hepatitis, and so on). Of

Discussion

In the present study, we devised a novel index to detect the presence of NAFLD using BMI and the results of routinely performed laboratory tests. Moreover, the performance of HSI for detecting NAFLD was confirmed in the validation cohort.

Many studies have attempted to devise noninvasive methods that can predict the presence of NAFLD. Conventional radiological imaging studies, such as US, CT, and magnetic resonance imaging, have been shown to be reasonably accurate [11], [12], [13], [14]. For

Conflict of interest statement

None declared.

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