In the UK, approx. 25% of people registered with a GP are living with multimorbidity: having more than one long-term condition: e.g. diabetes, heart disease and dementia1. This is expected to become more common2. People from deprived backgrounds are worse affected, and more likely to have multiple conditions at younger ages1. Doctors and researchers are working to improve the health and care of people with multiple diseases. However, we also need to prevent people from developing multiple conditions. Many chronic diseases are partly caused by diet and how much we smoke, drink, and exercise. The societies we live in influence these ‘lifestyle choices’. Strategies to prevent long-term diseases can therefore focus on changing individual behaviour or the conditions around us. Background People with multiple conditions tend to have worse health, may have to take multiple medications, and often have many appointments with different doctors and nurses They are also more likely to have difficulties with mobility and daily activities, particularly in old age3. Multimorbidity is also a problem for the NHS, which is centred on care for specific individual diseases, making it hard to manage the care of patients with multiple conditions4. Estimating which strategies are most likely to stop people developing multiple conditions will help policy makers assess the different options. Predicting how many people may be living with multimorbidity in different scenarios can also inform the planning of services for future health and social care needs. Why is this topic important? Using data from 2004-2018 on 1m GP patients in England (from the Clinical Practice Research Datalink), we will estimate: • The number of people who are living with multiple conditions, and diagnosed each year • How diseases accumulate over the life-course: • How age, sex, and deprivation affect the above results What are the trends over time and how are different people affected? • There are many definitions of “multimorbidity”, e.g. having 2+ conditions lasting over 1 year, or including only certain diseases. Different definitions help to answer different questions, and healthcare workers and patients may have different priorities. • We aim to develop a definition of multimorbidity relevant for prevention, taking into account risk factors for disease and combining what is important for patients, healthcare workers, and the NHS. How should we define multimorbidity for prevention? • We will use a model (IMPACTNCD 5) to compare the effectiveness of different potential individual-level and structural prevention strategies. • A key component will be estimating which strategies are fairest to people living in the most deprived areas. • Examples strategies include structural policies on food e.g. marketing regulation or taxation; and individual level strategies e.g. NHS health checks and screening. What might help stop people developing multiple conditions? How can we reduce the future number of people living with more than one long-term health problem? Anna Head, Martin O’Flaherty, Kate Fleming, Chris Kypridemos Department of Public Health and Policy, University of Liverpool This project is funded by the University of Liverpool and supported by the National Institute for Health Research (NIHR) School for Public Health Research (Grant Reference Number PD-SPH-2015-10025). The views expressed are those of the author(s) and not necessarily those of the NIHR or the Department of Health and Social Care. Overall Aim: To look at whether and by how much we can stop people from developing multiple long-term conditions and what might be the best ways of doing this. Throughout, we will focus on whether and how people from more deprived areas of England have been or would be worse affected. We have 3 main research questions: Time to 2nd Time with multimorbidity Time to 1st disease Age Disease-free 1 disease 2 diseases 3+ REFERENCES: [1] Barnett et al. 2012. Epidemiology of multimorb