The Prevalence of Non-Alcoholic Fatty Liver Disease in Young Adults in the UK

Abstract

Background: Crude estimates of non-alcoholic fatty liver disease (NAFLD) prevalence worldwide are 25% amongst all adults whilst prevalence in young adults remains unclear. We aim to estimate prevalence of NAFLD in young adults in a sample of 22-26year olds recruited through the Avon Longitudinal Study of Parents and Children (ALSPAC), using transient elastography (TE) and controlled attenuated parameter (CAP). Methods: 4021 participants attended clinic for fibroscan using the Echosens 502 Touch®; mean age 24yrs (+/- 0·8). Results with interquartile range/median ratio > 30% were excluded when analysing fibrosis, but not CAP. Data was collated on TE result, CAP score (S3 >66% hepatic steatosis), body mass index (BMI), serology including alanine transaminase (ALT), aspartate aminotransferase (AST), and gamma-glutamyl transferase (GGT). Findings: 3678 CAP scores were eligible for analysis. 780 (20·7%) participants had steatosis; 48·3% (n=377/780) had S3. ALT, AST and GGT all increased with CAP score (p<0·001). Overweight and obese BMI were positively associated with steatosis when adjusted for alcohol excess, social class and smoking (OR 5·17 [95%CI 4·11-6·50] and OR 27·27 [95%CI 20·54-36·19] respectively; p<0·001). 3600 TEs were eligible for fibrosis analysis. 104 participants (2·9%) had TE ≥7·9kPa. 9 participants had TE equivalent to F4 fibrosis. CAP score was positively associated with fibrosis on univariable regression (S3 OR 1·93 [95%CI 1·11-3·37]; p<0·001) but only individuals with harmful alcohol consumption and steatosis had increased fibrosis odds when adjusted for social class and smoking (OR 4·02 [95%CI 1·24- 13·02]; p=0·02). Interpretation: 1 in 5 young people had steatosis and 1 in 40 had evidence of fibrosis at 24yrs. The UK obesity epidemic is affecting young adults and requires greater public health interventions to prevent increasing health care burden due to NAFLD related advanced liver disease in later life. Funding Statement: The UK Medical Research Council and Wellcome (Grant ref: 102215/2/13/2) and the University of Bristol provide core support for ALSPAC. This work was undertaken with the support of the MRC and Alcohol Research UK (MR/L022206/1), and the David Telling Charitable Trust. The authors also acknowledge support from The Centre for the Development and Evaluation of Complex Interventions for Public Health Improvement (DECIPHer), a UKCRC Public Health Research Centre of Excellence (joint funding (MR/KO232331/1) from the British Heart Foundation, Cancer Research UK, Economic and Social Research Council, Medical Research Council, the Welsh Government and the Wellcome Trust, under the auspices of the UK Clinical Research Collaboration), the NIHR School of Public Health Research, NIHR Health Protection Research Unit in Evaluation and NIHR Biomedical Research Centre at the University Hospitals Bristol NHS Foundation Trust and the University of Bristol. Declaration of Interests: The authors stated: None to declare. Ethics Approval Statement: Ethical approval for the study was obtained from the ALSPAC Ethics and Law Committee and the Local Research Ethics Committees. Consent for biological samples has been collected in accordance with the Human Tissue Act (2004). Informed consent for use of data collected via questionnaires and clinics was obtained from participants following the recommendations of the ALSPAC Ethics and Law Committee at the time.