Nonalcoholic Fatty Liver Disease, Liver Fibrosis, and Cardiometabolic Risk Factors in Adolescence: A Cross-Sectional Study of 1874 General Population Adolescents

Context: The impact of adolescent nonalcoholic fatty liver disease (NAFLD) on health, independent of fat mass, is unclear. Objective: The objective of the study was to determine the independent (of total body fat) association of ultrasound scan (USS)-determined NAFLD with liver fibrosis, insulin resistance, and dyslipidemia among healthy adolescents. Design: This was a cross-sectional analysis in participants from a UK birth cohort. Participants: One thousand eight hundred seventy-four (1059 female) individuals of a mean age of 17.9 years participated in the study. Main Outcomes: USS assessed liver stiffness (shear velocity, an indicator of fibrosis) and volume, fasting glucose, insulin, triglycerides, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, alanine amino transferase, aspartate amino transferase, γ-glutamyltransferase, and haptoglobin. Results: The prevalence of NAFLD was 2.5% [95% confidence interval (CI) 1.8–3.3] and was the same in females and males. Dual-energy X-ray absorptiometry determined total body fat mass was strongly associated with USS NAFLD: odds ratio 3.15 (95% CI 2.44–4.07) per 1 SD (∼10 kg) fat mass. Those with NAFLD had larger liver volumes and greater shear velocity. They also had higher fasting glucose, insulin, triglycerides, low-density lipoprotein cholesterol, alanine amino transferase, aspartate amino transferase, γ-glutamyltransferase, and haptoglobin and lower high-density lipoprotein cholesterol. Most associations were independent of total body fat. For example, after adjustment for fat mass and other confounders, hepatic shear velocity [mean difference 22.8% (95% CI 15.6–30.5)], triglyceride levels [23.6% (95% CI 6.0–44.2)], and insulin [39.4% (95% CI 10.7–75.5)] were greater in those with NAFLD compared with those without NAFLD. Conclusion: In healthy European adolescents, 2.5% have USS-defined NAFLD. Even after accounting for total body fat, those with NAFLD have more adverse levels of liver fibrosis and cardiometabolic risk factors.