Association between weight-adjusted waist index and hepatic steatosis and fibrosis: Analyses of the NHANES 2017 to 2020

The weight-adjusted waist index (WWI) is emerging as a novel indicator for assessing obesity, which is known to correlate with nonalcoholic fatty liver disease (NAFLD), a condition that can lead to hepatic steatosis and fibrosis. This research aims to explore the possible link between WWI and liver steatosis and fibrosis. We conducted a cross-sectional analysis using data from 2017 to 2020 National Health and Nutrition Examination Survey. Controlled attenuation parameter (CAP) and liver stiffness measurement (LSM) were used to diagnose hepatic steatosis and fibrosis, respectively, by vibration-controlled transient elastography, and multivariate logistic regression analysis was employed to examine the association between WWI and the 2. The non-linear relationship was described using threshold effect analyses and fitting smoothed curves. We also performed interaction tests and subgroup analyses, considering factors such as age, gender, body mass index, hypertension, diabetes, and smoking habits. Receiver operating characteristic curves were used to estimate cutoff points for identifying NAFLD. This study included 5535 adults. Results showed that higher levels of WWI are correlated with higher CAP scores, and the strong association between WWI and CAP was still evident after accounting for all covariates (odds ratios = 12.22, 95% confidence interval: 8.63-15.80). Subgroup analyses found a robust positive correlation between WWI and CAP in individuals with hypertension (P for interaction = .018). A non-linear positive correlation with a breakpoint of 11.12 was identified between WWI and CAP. But no significant correlation between WWI and LSM was found through multiple regression analyses (odds ratios = 0.10, 95% confidence interval: -0.17 to 0.37). Nevertheless, based on smoothed curve fitting, WWI and LSM formed a U-shaped relationship, showing a positive connection when WWI was above 11, when WWI dropped below 11, it showed a negative connection. Finally, the receiver operating characteristic analysis results indicated that the WWI cutoff point for identifying NAFLD was 10.8870. To validate these results, further extensive and prospective studies are required.