Impact of the new definition of metabolic dysfunction–associated fatty liver disease on detection of significant liver fibrosis in US adolescents

Recently, an expert panel proposed diagnostic criteria for metabolic dysfunction–associated fatty liver disease (MAFLD) in the pediatric population. The aim of this study was to evaluate the prevalence of MAFLD among US adolescents and to investigate whether the new MAFLD definition is able to identify individuals with more advanced liver disease. We analyzed data from participants 12–18 years old included in the 2017–2020 cycles of the National Health and Nutrition Examination Survey, a large survey aimed at including individuals representative of the non-institutionalized general US population. Participants with a complete vibration-controlled transient elastography exam were included. Steatosis was evaluated through the median controlled attenuation parameter (CAP) and fibrosis through median liver stiffness measurement (LSM). Recently proposed criteria for the diagnosis of MAFLD were applied. Multivariable logistic regression analysis was performed to evaluate the impact of the new MAFLD definition on the odds of significant liver fibrosis. We included a total of 1446 adolescents (mean age: 14.9 years; 52.0% male; 47.3% overweight or obese). No participant reported a previous history of viral hepatitis. Steatosis (CAP ≥ 248 dB/m) was present in 25.9% (95% confidence interval [CI] 23.3–28.9) of individuals, and among these, 87.7% met the MAFLD criteria. Only 22.9% of patients with steatosis had elevated alanine aminotransferase levels. Among participants with steatosis, prevalence of significant liver fibrosis (LSM ≥ 7.4 kPa) did not differ significantly according to whether they met MAFLD criteria (9.7% vs. 15.2%, p = 0.276). In the multivariable model, odds of significant fibrosis did not differ significantly between these two groups. MAFLD criteria are met by most US adolescents with elastographic evidence of steatosis. Nonetheless, these criteria do not appear to improve detection of subjects with more advanced liver disease. Further longitudinal studies are needed to evaluate whether metabolic dysfunction is associated with faster progression toward inflammation, fibrosis, and liver-related events.