Title: Diet and physical activity behaviour, and the relationship with cardiovascular disease risk and quality of life after liver transplantation: a systematic review, cohort and qualitative study.
Funder: Department of Health and Social Care

Abstract: Background Liver transplant cures liver disease and long-term survival is excellent. Quality of life (QOL) after transplant is important, and although liver transplant improves this, QOL may be poorer than controls. New onset cardiovascular disease (CVD) and risk factors, such as obesity, diabetes, dyslipidaemia and hypertension, are common after transplant and increase the risk of morbidity, premature mortality and greater healthcare cost.It makes sense that good diet and physical activity are important to reduce CVD risk and improve QOL after liver transplant. However, post-transplant diet and physical activity behaviours, the determinants of these behaviours and which components of diet and physical activity are most important for CVD risk and QOL are not understood. These are important to investigate as they might be different to the general population due to the impact of immunosuppressive medication on CVD risk and as a result of the high energy diet required before and at the time of liver transplant. Without this knowledge the best way to support liver recipients with lifestyle behaviours is not known.Patient and public involvement Liver transplant patients have guided the research questions and reviewed research methods, which have been revised according to their feedback. Four liver transplant patients, two relatives and a liver transplant patient charity will continue to advise on research design, interpretation and dissemination throughout the project.Research questions What are the diet and physical activity behaviours of liver transplant recipients? What are the determinants of diet and physical activity behaviours in liver transplant recipients? Are diet and physical activity behaviours associated with CVD risk and QOL after liver transplant? Methods Study one A systematic review of literature investigating the determinants and correlates of diet and physical activity behaviour in liver transplant recipients. Qualitative research using thematic analysis and if appropriate quantitative research will be synthesised using meta-analysis.Study two A cohort study will investigate the diet and physical activity behaviours of liver transplant recipients and examine their associations with CVD risk, QOL and behaviour determinants. Patients undergoing liver transplant at one UK transplant centre during one year will be recruited. Data will be collected at 6 and 12 months after transplant. Diet will be measured using recall and plasma carotenoids, and physical activity using accelerometers. QOL, behaviour determinants, HbA1c, lipid profile, blood pressure, weight, height and body composition will be measured. Multivariable regression models will examine associations between behaviours and CVD risk, QOL and determinants.Study three Semi-structured interviews at 6-12 months post-transplant will be used to explore patients' experiences of diet and physical activity behaviour determinants. Participants from study two will be recruited using purposive sampling until saturation is achieved. Analysis will use an inductive approach with thematic framework method.Impact This study will help clinicians to better support patients with diet and physical activity behaviours. This provides the potential to improve outcomes and achieve cost savings, for example through fewer hospital admissions with CVD and other related conditions. The study will inform the future development of an effective lifestyle intervention post-transplant.

Lay abstract: Why is this research needed? Liver transplant cures liver disease and people go on to live for many years. Having a good quality of life and feeling well after transplant is important. A lot of people become overweight or get high cholesterol, high blood pressure or diabetes after liver transplant. People with these problems are more likely to be unwell or die from heart disease or other health problems than those without. It makes sense that good diet and physical activity are important to stay healthy and feel well. But we don't know what people eat, how active they are or what influences their diet and physical activity after liver transplant. We also don't know which parts of diet and activity are most important to health and wellbeing for people who have had a liver transplant. For example, is it length of time or amount of effort with physical activity that is more important? This is important to understand as it might be different from people who have not had a transplant due factors such as transplant medication.What will this research find out? This research has three aims, to find out for people who have had a liver transplant: What they eat and what physical activity they do. Why they eat the way they do, and why they are physically active or not. If their diet and physical activity are linked to changes in quality of life and risk of heart disease. Knowing this will mean we can help people who have liver transplant to stay healthy by giving better advice about diet and physical activity. It will also help us to plan a programme that teaches about diet and physical activity. We can then test the programme in future research to see if it helps improve health and wellbeing after liver transplant. What will this research involve? This research includes three studies.Study one I will find and review all previous studies that have looked at what people eat and how much physical activity they do after a liver transplant and why they eat way they do, or are physically active or not.Study two I will invite people who have a liver transplant at one UK transplant centre between May 2019 and April 2020 to take part. I will find out what they eat and what physical activity they do at 6 and 12 months after liver transplant. I will see if diet and physical activity are linked with weight, body muscle, body fat, risk of heart disease and quality of life. I will also find out what influences what people eat or the activity they do.Study three I will interview people when they are 6-12 months after liver transplant about their experiences of diet and physical activity. I will ask them to tell me about the things that influence what they eat and the physical activity they do.How will patients or the public help guide the research? People who have had a liver transplant, their friends and family have told me this research is important to them. They have helped to plan the details of the project and will continue advising me all the way through the research.How will the findings be shared? The findings will be published in research journals. I will also share findings through presentations, public events, emails, social media and patient newsletters. I will share results with study participants, healthcare teams working in liver transplant across the UK, liver transplant patients, the public and groups who plan liver transplant guidelines and policies in the UK.

Research activity codes: 7.1 INDIVIDUAL CARE NEEDS
Health categories: ORAL AND GASTROINTESTINAL;CARDIOVASCULAR