Non-alcoholic Fatty Liver Disease in Overweight and Obese Children; Can Ultrasonography Substitute Laboratory Studies? A Case-Control Study

Background: Non-alcoholic fatty liver disease (NAFLD) comprises a large burden on the global healthcare system with a high prevalence and lethal outcomes. Moreover, this disease is showing an incremental trend over time, partly due to the rise in obesity rates among children. Objectives: In this study, we aimed to elucidate the correlation of ultrasonographic and laboratory-assisted diagnosis of NAFLD in obese and normal-weight children. Methods: This study assessed 50 pediatric obese or overweight children with BMIs higher than the 85th percentile for their age and sex, as well as 50 age-and sex-matched control counterparts using ultrasonography and a liver enzyme panel. The prevalence of NAFLD and the differences in lab studies were evaluated. Then, receiver operating characteristics (ROC) curves were used to determine the optimal cut-off value for NAFLD based on liver enzymes. Results: A total of 100 participants were included in this study, 58% of whom were male. The mean age of the participants was 10.41 ± 2.224 years. The prevalence of sonographically diagnosed NAFLD in obese and overweight children was 34.0% (95% CI: 21.2% - 48.8%). The prevalence of NAFLD when assessed by lab values in this population was 58.0% (95% CI: 43.2% - 71.8%), with a low measure of agreement (K = 0.239, P = 0.058). High BMI increased the risk of NAFLD to about 8.5 times its baseline in the normal-BMI population. Non-alcoholic fatty liver disease patients had significantly higher values for aspartate aminotransferase (AST) (P < 0.001), alanine aminotransferase (ALT) (P < 0.001), and gamma-glutamyl transferase (GGT) (P < 0.001), but not alkaline phosphatase (ALP) (P = 0.743). The ROC curves for AST, ALT, GGT, and BMI percentile had areas of 0.800, 0.899, 0.807, and 0.874, respectively, all of which could be used for screening NAFLD. A cut-off value of 43.5 IU/L for AST had a specificity and positive predictive value of 100% for the diagnosis of NAFLD in children. Conclusions: Obese and overweight children are 8.5 times more likely to develop NAFLD compared to their normal-BMI peers. For the evaluation of this disease, liver enzyme panels integrated with ultrasonographic assessment should be utilized.