A broader economic evaluative space for public health interventions: an integrated approach

Introduction: There is an increasing need for economic evaluation of public health interventions to ensure efficient allocation of resources. Outcomes of such interventions often consists of health and non-health and do not fit in the conventional economic evaluation of quality-adjusted life year (QALY) framework. A cost-benefit analysis (CBA) could be appropriate but has concerns of assigning monetary values to health outcomes. Questions remain on how to consider the broad outcomes of a public health intervention in an economic evaluation. Objective: This thesis aimed to develop an integrated approach for an economic evaluation of a public health intervention that combines the standard cost-utility analysis (CUA) for health outcomes with the stated preference discrete choice experiment (SPDCE) approach for non-health outcomes on a single monetary metric. Methods: A natural experiment of the Woods In and Around Towns (WIAT) study in Scotland was used for empirical analysis. Costs were assessed using a top-down approach based on resources used. A difference-in-differences (DiD) approach was used to establish the impact. A CUA valued the health outcomes in terms of QALYs while a previously developed conceptual model of the WIAT was used to identify the SPDCE attributes and levels for the non-health outcomes. The WIAT study questionnaire was mapped to the SPDCE which generated relative willingness to pay (WTP) values from a general Scottish population. The WTP estimates were applied to the changes or improvements in the attributes and levels resulting from the intervention. A net monetary benefit (NMB) framework was then used to combine the CUA with the SPDCE on the same monetary scale, effectively deriving a CBA. Results: The WIAT interventions were of low cost despite the base case DiD analysis showing a statistically insignificant effect for interventions. The incremental cost-effective ratios (ICERs) for the interventions revealed that they were cost-effective. The probabilistic sensitivity analysis (PSA) showed that the physical intervention was 73% likely to be cost-effective at WTP of £20,000 and £30,000. The combined physical and social interventions had 74% and 75% likelihood of being cost-effective at WTP of £20,00 and £30,000, respectively. There was a great deal of uncertainty around QALY results. Overall, the integrated approach revealed that the WIAT interventions were cost-beneficial in terms of both health and non-health outcomes. Conclusion: This thesis has proposed and demonstrated the integrated approach that combines the conventional QALY framework with the SPDCE on a single monetary scale, hence a broader economic evaluative space particularly suitable for an economic evaluation of a public health intervention

Health impacts of environmental and social interventions designed to increase deprived communities' access to urban woodlands: a mixed-methods study

Background: Contact with natural environments can bring health benefits, but research is lacking on how changes in access to natural environments might improve health, especially for deprived populations. Objective: To evaluate the health impacts of woodland environment interventions intended to increase communities’ engagement with these woodlands. Design: A prospective study of Forestry Commission Scotland’s Woods In and Around Towns (WIAT) programme in deprived communities to enhance public access to natural environments. The study investigated the impact that WIAT had on community-level mental health over time. Setting: Three intervention and three control woodland sites, and associated communities within 1.5 km of the woodlands, located in central Scotland and eligible for WIAT support. Participants: A core community survey was administered at each site in three waves, at baseline and after each phase of intervention (n = 5460, panel A). The completed survey contained a nested longitudinal cohort (n = 609, panel B). Community members also undertook 6-monthly environmental audits at all sites (n = 256) and participated in post-intervention focus groups (n = 34). Interventions: Phase 1 involved physical changes to the woodlands, including footpaths, entrances and vegetation. Phase 2 involved community engagement events promoting woodland use. Main outcome measures: The primary outcome was the Perceived Stress Scale (PSS). Other health measures included health-related quality of life (HRQoL) EuroQol-5 Dimensions (EQ-5D), physical activity (PA) [International Physical Activity Questionnaire (IPAQ)], connectedness to nature [Inclusion of Nature in Self (INS) scale] and social cohesion. Results: The PSS scores significantly increased in the intervention group and marginally decreased in the control group. Multilevel regression models showed a differential impact between the intervention and the control at survey wave 3 in panel A [B (unstandardised coefficient) 3.58, 95% confidence interval (CI) 2.85 to 4.31; p < 0.001] and in panel B [B 3.03, 95% CI 1.54 to 4.52; p < 0.001]. Using the same analytical approach, no significant change in HRQoL was associated with the intervention. Economic assessment included an illustrative cost–utility analysis and a cost–consequences analysis. The differential in stress between the intervention group and the control group was lower or non-significant in those who visited ‘nature’ in the previous year [panel A, B 1.9, 95% CI 0.8 to 3.0; p < 0.001; panel B, B 0.64, 95% CI –1.60 to 2.88; p = 0.57]. The IPAQ score showed a positive association with the intervention for moderate levels of PA [panel B, B 559.3, 95% CI 211.3 to 907.2; p = 0.002] and overall PA [panel B, B 861.5, 95% CI 106.5 to 1616.4; p = 0.025]. The intervention was also associated with increased nature connectedness and social cohesion by wave 3 – significant for panel A only. Qualitative and quantitative evidence showed that interventions increased the perceived quality of the woodland environment and enhanced its enjoyment for different activities, but the increase in use of natural environments post intervention was only 6% (panel B). Limitations: This study was limited to three intervention sites. External factors may be the primary influence on health outcomes. Conclusions: The WIAT interventions did not improve community-level health within 6 months of completion, and hence there was no basis for demonstrating cost-effectiveness. However, the WIAT interventions are low cost (average £11.80 per person in the eligible population) and have potential for cost-effectiveness, if health benefits were found in the longer term. Future work: Using routinely collected data to consider a whole-programme evaluation is recommended

Enhancing Health Through Access to Nature: How Effective are Interventions in Woodlands in Deprived Urban Communities? A Quasi-experimental Study in Scotland, UK.

High prevalence of poor mental health is a major public health problem. Natural environments may contribute to mitigating stress and enhancing health. However, there is little evidence on whether community-level interventions intended to increase exposure to natural environments can improve mental health and related behaviours. In the first study of its kind, we evaluated whether the implementation of a programme designed to improve the quality of, and access to, local woodlands in deprived communities in Scotland, UK, was associated with lower perceived stress or other health-related outcomes, using a controlled, repeat cross-sectional design with a nested prospective cohort. Interventions included physical changes to the woodlands and community engagement activities within the woodlands, with data collected at baseline (2013) and post-intervention (2014 and 2015). The interventions were, unexpectedly, associated with increased perceived stress compared to control sites. However, we observed significantly greater increases in stress for those living >500 m from intervention sites. Visits to nearby nature (woods and other green space) increased overall, and moderate physical activity levels also increased. In the intervention communities, those who visited natural environments showed smaller increases in stress than those who did not; there was also some evidence of increased nature connectedness and social cohesion. The intervention costs were modest but there were no significant changes in quality of life on which to base cost-effectiveness. Findings suggest factors not captured in the study may have contributed to the perceived stress patterns found. Wider community engagement and longer post-intervention follow-up may be needed to achieve significant health benefits from woodland interventions such as those described here. The study points to the challenges in evidencing the effectiveness of green space and forestry interventions to enhance health in urban environments, but also to potential benefits from more integrated approaches across health and landscape planning and management practice