Title: Informing the design of a behavioural intervention to decrease sedentary time in older adults
Funder: Department of Health and Social Care

Abstract: Background: Ageing well is now a global health priority given that the population of older adults is expected to double to 22% from 2015 to 2050. Older adults spend an average of 9.4 hours/day being sedentary, placing them at significant risk of type 2 diabetes, cardiovascular disease, cancer and premature mortality. While the impact of sedentary time is attenuated among those who are sufficiently physically active, this applies to a small minority of the population. Furthermore, few interventions have led to sustained increases in physical activity. Consequently, if we could reduce sedentary time, we could potentially improve the health and well-being of older adults, and reduce the current burden on health and social care resources due to these chronic conditions. While many studies have been conducted on the associations between sedentary time and the risk of chronic diseases, very little is known about how best to achieve population-level reductions in sedentary time among older adults. Further, we know little about the potential benefits that these reductions might have on other aspects of health that are particularly important for successful ageing (e.g., functional health and quality of life). Improvements in functional health and quality of life may prove important in successfully motivating older adults to change their sedentary behaviour. Although some studies have attempted to answer these questions, there are key limitations of the research that has been conducted to date. These limitations need to be addressed to improve our understanding of the role of sedentary behaviours in human health and ultimately in improving population health. Aims: To describe change in sedentary time (Study 1) and its correlates among older adults (Study 2) To identify effective components of existing interventions targeting sedentary time (Study 3) To synthesise existing knowledge on the association of sedentary time with quality of life (QoL) and functional health outcomes (Study 4) To quantify associations of change in sedentary time with functional outcomes and QoL (Study 5) Plan: I will perform epidemiological analyses within EPIC-Norfolk (n=3705), a large population-based cohort of older adults in which participants wore hip-mounted accelerometers for 7 days at two health checks separated by six years. I will use multi-level regression models to describe change in sedentary time and its correlates. Correlates will be divided into four domains (socio-demographic, behavioural, physical health and social and physical environment). I will conduct a systematic review of interventions targeting sedentary time in older adults. I will use multi-level modelling in EPIC-Norfolk to quantify associations of change in sedentary time with functional outcomes (grip strength, gait speed, leg strength) and QoL (EQ-5D). I will conduct a systematic review of associations of sedentary time with QoL and functional outcomes. I will synthesise findings to develop recommendations for designing interventions to reduce sedentary time in older adults. Potential Benefit: With an ageing population, prevention and modification of risk factors is more important. This work will inform the design and targeting of interventions to reduce sedentary time. If effective, such interventions could improve health in older adults and reduce NHS and social care cost in an increasingly overburdened NHS.

Lay abstract: Context: People who sit or lie down a lot (for example, when watching television) are more likely to die earlier than people who sit or lie down less. Researchers call this being sedentary. Unfortunately, we know very little about why some people are more sedentary than others and how best to help older people to be less sedentary. Furthermore, we do not know if being sedentary has an impact on other important aspects of health including people's ability to move (what doctors call functional health) and how happy they are with their life and health overall (what doctors call quality of life (QoL)). If we answer these questions, we could potentially improve the health of our ageing nation and reduce health and social service costs. The goal of my work is to figure out how to best help people limit the amount of time that they are sedentary and how doing this might also improve their functional health and quality of life. To answer these questions I will conduct five studies. Aims: In Study 1 I will describe, in a large sample of older UK adults, how sedentary time changes over six years. In Study 2 I will figure out which factors are linked to increases in sedentary time. In Study 3 I will review all previously used approaches aiming to reduce sedentary time and identify which approaches were the most effective in reducing sedentary time. The findings of my first three studies will help me make recommendations on how future doctors, nurses, public health officials and policymakers can help older people decrease their levels of sedentary time and therefore also decrease their risk of dying early. I will then conduct two studies in which I will figure out if people who are more sedentary time have lower functional health and poorer quality of life. I will do this by summarising the findings of other researchers on this topic (Study 4) and by conducting my own study on a large sample of older UK adults (Study 5). Design and Methods: For Studies 1, 2 & 5, I will use data collected on nearly 4000 participants who were followed up for 6 years as part of the EPIC-Norfolk Study. Functional health measures (walking speed, grip strength, sit-to-stand tests) were assessed by trained research assistants. QoL was assessed using questionnaires. Sedentary time was assessed for 7 days using a small device like a step counter called an accelerometer. I will use mathematical models to figure out how much sedentary time changes over time (Study 1), the factors linked with these changes (Study 2), and if sedentary time influences functional health and QoL (Study 5). In Studies 3 & 4, I will summarise existing evidence on what interventions have previously been developed for decreasing sitting time among older adults and what we know about the link between sedentary time and functional health and QoL. I will put together these findings to develop recommendations for a new approach to reduce sedentary time in older adults. Significance: My work will contribute to our understanding of the role of sedentary time in health and wellbeing and will inform the development of strategies that may improve the health of older adults and reduce health care costs. Patient and Public Involvement: I will consult with my GI-PPI group, the EPIC-Norfolk PPI group, Age-UK and the British Heart Foundation biannually to get feedback on the study findings and to help shape future health recommendations. Dissemination: I will publish my results in peer-review journals and share my results at both local and international conferences. I will also work closely with our media relations expert to ensure that findings are disseminated to the public, and to interested parties in the NHS and Public Health England.

Research activity codes: 3.1 PRIMARY PREVENTION INTERVENTIONS TO MODIFY BEHAVIOURS OR PROMOTE WELL-BEING
Health categories: GENERIC HEALTH RELEVANCE