Prevention and detection of liver disease in the general population

Liver disease is the third biggest cause of premature death in the UK, yet two of its main causes - alcohol consumption and obesity – are modifiable risk factors, potentially amenable to public health prevention interventions. Chronic liver disease is generally progressive, usually starting with mild fibrosis and continuing through to cirrhosis. Signs and symptoms often do not appear until disease is at an advanced stage. As a result, many patients present late to healthcare services and outcomes are poor. Consequently, this work focused on the general population of the UK, where prevention strategies would best be targeted. The aim is to better understand the epidemiology of those at risk of liver disease due to obesity and alcohol consumption, and how disease may be identified early in its course, in order to improve patient outcomes.To address this, large datasets from general population settings were analysed. This included conducting a meta-analysis of cohort studies, and analyses of national survey datasets. This thesis describes the distribution and overlap of alcohol and obesity risk factors for liver disease; risk of liver disease associated with individual risk factors and their combinations; distribution of non-invasive markers of liver disease; associations between non-invasive markers of liver disease and risk factors; and associations between overweight /obesity and calories from alcohol.Key findings were that the majority of the UK general population have at least one risk factor for liver disease and nearly 30% have multiple risk factors. Awareness of the risk factors for liver disease in the general population was very low (4%). There was a significantly increased risk of liver disease associated with the combination of drinking above recommended alcohol consumption guidelines and being overweight or obese (OR 3.60 (95%CI 3.22 to 4.02) for overweight, OR 5·84 (95%CI 5·09 to 6·70) for obese). Some 12% of the general population had acombination of increased alcohol consumption and increased BMI. We suggest the term ‘BAFLD to describe these people at risk of Both Alcohol and Fatty Liver Disease. Non-invasive markers of liver disease showed significant variation in positivity in the general population setting, they were not concordant and their performance differed significantly between risk factor categories. Abnormal liver blood tests were found in 11% of the population. Calorie consumption was higher in those who consumed alcohol, and alcohol calories were consumed in addition to usual calorie intake. Weekly calorific intake from alcoholic beverages increased significantly with increasing BMI. Mean extra calories on days when participants consumed alcohol were 428 kcal (95%CI 396 to 460).The data presented here further our knowledge of who is at risk of liver disease; the interplay of risk factors; the use of non-invasive markers in a general population setting; and the contribution of calories from alcohol in those with existing risk from increased BMI. It is hoped this evidence will inform risk stratification protocols, clinical pathways, prevention strategies and public health policy, in order to improve prevention and detection of chronic liver disease in the UK population