The health economics of physical inactivity and sedentary behaviour
: Healthcare expenditure and cost-effective interventions

  • Leonie Heron

Student thesis: Doctoral ThesisDoctor of Philosophy


Physical inactivity and sedentary behaviour increases the risk of premature mortality and chronic diseases such as cardiovascular disease (CVD), type 2 diabetes (T2D), and cancers. Globally, the prevalence of these risk factors is increasing, putting many people at increased risk. Physical inactivity and sedentary behaviour are an economic burden due to direct healthcare costs and indirect costs from reduced productivity, increased absenteeism, and other out-of-pocket costs. Previous studies have estimated the healthcare costs associated with physical inactivity using a prevalence-based approach and self-reported data, however no estimates were available for sedentary behaviour and none had estimated the costs using objectively measured data. The Global Action Plan for Physical Activity (GAPPA) from the World Health Organisation (WHO) has set out ambitious targets to reduce physical inactivity by 15% by 2030, however there is no indication that we are on course to meet those goals. Greater understanding of the economic burden of physical inactivity and sedentary behaviour could be used to build a financial case to persuade policymakers to prioritise interventions that can increase activity. Importantly, the interventions to reduce physical inactivity and sedentary behaviour should be both cost-effective overall and reduce existing health inequalities. Therefore, the aim of this thesis was to estimate the direct healthcare costs associated with prolonged sedentary behaviour and physical inactivity in the United Kingdom (UK) and to explore the cost-effectiveness of interventions to reduce physical inactivity, using both individual and population-level perspectives.

Study one (see Chapter 3): The aim of this study was to estimate the annual direct healthcare costs of prolonged sedentary behaviour to the National Health Service (NHS) in the UK. There is moderate-strong evidence that prolonged sedentary behaviour increases the risk of five diseases: CVD, T2D, lung cancer, colon cancer, and endometrial cancer. Population attributable fractions (PAFs) were calculated for these five diseases using relative risks (RRs) extracted from meta-analyses and information on the prevalence of sedentary behaviour. The PAFs represent the proportion of incident cases of the diseases which are attributable to sedentary behaviour in the population. The PAFs were then applied to NHS budgetary data to estimate the proportion of costs attributable to sedentary behaviour. After adjustment for potential double-counting due to comorbidities, the estimated total annual cost to the NHS was £0.7bn in 2016-17 costs. Sedentary behaviour places a substantial economic burden to the NHS in the UK.

Study two (see Chapter 4): This study aimed to assess the relationship between physical activity level and inpatient healthcare use and costs in a large sample (n = 86,067) of the UK Biobank cohort. The UK Biobank study links sociodemographic and lifestyle information with health data and NHS records, including inpatient hospital records. Participants were divided into tertiles based on their physical activity recorded by accelerometers over one week. Subsequent inpatient hospital episodes were monetised using 2017 unit costs of health and social care from the Personal Social Services Research Unit (PSSRU). Generalised linear models (GLMs), adjusted for potential confounders such as BMI, health status and sociodemographic factors, estimated the differences in monthly days spent as a hospital inpatient and monthly inpatient costs. The more active tertiles spent on average 0.3 and 0.5 fewer days per year as an inpatient and £3.09 and £3.81 less in inpatient costs per month than the least active tertile. The effect of physical activity level on inpatient costs appeared to be stronger in women and the lowest income groups. The findings indicate that policymakers should aim to reduce physical inactivity in the UK population overall and consider interventions which target women and lower-income groups, which may improve health inequalities.

Study three (see Chapter 5): This study aimed to assesses which characteristics of physical activity and sedentary behaviour interventions are associated with cost-effectiveness in healthy adults. A systematic review was conducted to identify economic evaluations of physical activity and sedentary behaviour interventions which had included healthy adults in randomised controlled trial (RCT) studies compared to usual care or a suitable control group. The characteristics of interest were behaviour change techniques (BCTs); complexity measured by the intervention Complexity Assessment Tool for Systematic Reviews (iCAT_SR) toolthe iCAT_SR tool; and intensity of the interventions measured by intervention duration, number of contact points, and number of contact hours. Thirty-three studies, describing 25 interventions, were eligible for inclusion. Physical activity outcomes were converted to MET-hours where possible and ICERs were calculated based on the cost of the interventions. Cost-effectiveness ranged from £0.04 to £62.82 per metabolic equivalent of task- (MET-) h/week gained. BCT clusters (1) Goals and planning; (2) Feedback and monitoring; (3) Social support; (4) Shaping knowledge; and (9) Comparison of outcomes were most frequently used in the most cost-effective interventions, indicating that those clusters might be associated with greater cost-effectiveness. In terms of complexity, the more cost-effective interventions were slightly less complex than the less cost-effective interventions. A minimum level of complexity might be necessary to achieve effectiveness; however, increasing complexity may lead to high costs that risk reduced cost-effectiveness. No relationship was identified between intervention intensity and cost-effectiveness. These findings could be useful to researchers developing cost-effective physical activity and sedentary behaviour interventions.

Study four (see Chapter 6): This study aimed to conduct a social return on investment (SROI) of the Connswater Community Greenway (CCG), an urban regeneration project in Belfast, Northern Ireland (NI). The benefits arising from the CCG in eight different areas were explored. There was sufficient evidence available to monetise the benefits in five areas: property values; flood alleviation; tourism; biodiversity; and climate change. Over the CCG’s expected lifetime of 40 years, the total social present value was estimated to be between £205,123,322 and £227,689,852. The cost of the CCG is an estimated £40 million. Therefore, the benefit-cost ratio (BCR) of the CCG is between 5.13 and 5.69. The results indicate that the CCG is likely to be a good investment.

In summary, this thesis estimated the economic burden of sedentary behaviour and physical inactivity and explored the cost-effectiveness of interventions to reduce these risk factors. Prolonged sedentary behaviour costs the NHS in the UK £0.7bn annually, after adjusting for confounders including physical activity and body mass index (BMI). Similarly, physical inactivity leads to increased inpatient hospital use and costs in the UK. At a population level, it is likely that physical inactivity costs the NHS hundreds of millions of pounds annually in inpatient costs alone. The effect may be stronger in women and low-income groups, presenting further evidence of health inequalities within the UK population. Physical inactivity and sedentary behaviour present an economic burden to the UK and urgent measures are required to encourage the population to become more active. Public health interventions (PHIs) have potential to address the growing prevalence of physical inactivity using individual-level and population-level approaches. A systematic review identified certain BCT clusters that may be associated with greater cost-effectiveness in physical activity interventions and found that complexity is important in interventions to achieve behaviour change. The intensity of the intervention did not appear to be associated with its cost-effectiveness. Finally, a SROI of the CCG found that the regeneration of the urban greenway was likely to be a good value investment for Belfast. Although there was insufficient evidence of an increase in physical inactivity in CCG residents, other social benefits identified results in a positive BCR.
Date of AwardJul 2021
Original languageEnglish
Awarding Institution
  • Queen's University Belfast
SponsorsNorthern Ireland Department for the Economy
SupervisorFrank Kee (Supervisor), Ciaran O'Neill (Supervisor) & Mark Tully (Supervisor)


  • Physical activity
  • sedentary behaviour
  • econometric analysis
  • economic evaluation
  • healthcare costs
  • systematic review
  • behaviour change
  • social return on investment

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