A positive relationship between weight-adjusted waist index and non-alcoholic fatty liver disease: a study on US adolescents

Abstract

Background: Non-alcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver condition in children, underscoring the urgent need for non-invasive markers for early detection in this population.

Methods: We utilized survey data from the National Health and Nutrition Examination Survey (NHANES) 2017-2020 regarding liver ultrasound transient elastography (LUTE) for the diagnosis of NAFLD (dependent variable), and used multiple logistic regression models to explore the association between weight-adjusted waist circumference index (WWI) and the prevalence of NAFLD in US adolescents. Smoothing curves and threshold effect analyses were used to assess the non-linear association between the independent variables and the dependent variable. Subgroup analysis was conducted to pinpoint particularly susceptible subgroups within our study cohort of 1,711 participants.

Results: Our findings indicated a positive correlation between WWI and NAFLD scores. Adjusting for all covariates revealed a significant association between increased WWI and the presence of NAFLD, with an odds ratio of 3.37 (95% CI: 2.74, 4.15). This association proved stronger than those observed with waist circumference, body mass index, and NAFLD. Stratifying WWI into quartiles showed a clear and strong positive correlation (P for trend < 0.0001). The results of smoothing curves and threshold effect analysis showed a non-linear relationship between WWI and NAFLD (LLR < 0.001). Notably, for WWI values below 10.65, a significant correlation was observed (OR = 5.25, 95% CI: 3.77,7.31). Additionally, our subgroup analysis revealed that WWI and NAFLD were associated more positively among male participants aged 16 years and older.

Conclusion: WWI is positively correlated with NAFLD in American adolescents and offers a straightforward and cost-effective method for identifying hepatic steatosis. The findings highlight the importance of focusing on individuals with a WWI below 10.65, where the risk of NAFLD increases. Priority should be given to the male adolescent population aged 16 and above.

Keywords: BMI; adolescents; liver steatosis; non-alcoholic fatty liver disease; waist circumference; weight-adjusted waist index.

FIGURE 1

Flow chart for participants.

FIGURE 2

The association of BMI, WC, and WWI with NAFLD. Red band represents a smooth curve fit between the variables. The blue bands represent the 95% confidence intervals of the fitted results. The independent variables were BMI (kg/m²) (A), WC (cm) (B), and WWI (C). All the covariates in Table 1 were adjusted.