PHIRN: Population Health Improvement Research Network

Executive Summary

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The growing incidence of chronic diseases has, in part, contributed to increased political and societal pressures to ensure public funds are allocated to the provision of services with known effectiveness. In other words, there is a call to action to ensure the programs and services implemented across Canada in population and public health are effective, and that they will result in improved health outcomes for Canadians. There is some evidence to suggest that current practices related to the promotion of the built environment may not adequately address inequities in health, and may even increase disparities. The purpose of this paper is to identify and summarize research findings on the effectiveness of population based interventions on the built environment, which was identified as a priority topic area in the annual report of the Ontario Chief Medical Officer of Health to the legislative assembly.

The health-evidence.ca registry was searched for reviews on the built environment in May 2011. A standardized quality assessment tool was used to assess the methodological quality of each identified review by two independent reviewers. All search results were limited to reviews rated as being of strong methodological quality. Extracted data included age of participants studied in the review, research design, methodological quality rating, details of the interventions evaluated, details describing which outcomes where evaluated as well as how they were measured, and outcome data.

The built environment search identified 37 high quality reviews, 27 of which reported on outcomes relevant to this synthesis. Outcomes reported on most frequently included: injuries and safety (N=11), mental health (N=8), physical activity behaviour (N=7), and household air quality (N=5). Participants studied ranged from the general population to children, adults, older adults, and ethnic and low income populations. Settings included roadways, worksites, and homes. The interventions evaluated can be classified into the following categories: traffic safety, occupational health, supportive housing, physical environment, falls prevention, home safety, child safety, and physical activity interventions.

The evidence related to the built environment with respect to injury prevention suggest that home safety education and/or the provision of low cost or free equipment to prevention injuries did not result in fewer injuries occurring among children in homes or visits to the emergency department.

A variety of built environment interventions focused on improving mental health outcomes among different populations. In instances where housing or neighbourhood regeneration is being implemented, there is some evidence of a positive effect on mental health outcomes among adults and male children, but not female children. Positive effects are observed in some studies as long as 2-3 years post intervention. In addition, there is some evidence, albeit not from rigorous studies, that access to green spaces, as well as rehousing, refurbishment, and relocation interventions are associated with better mental health outcomes. Alternatively, in instances where the impact of witnessing crime or being a victim of crime was explored, the evidence illustrates poorer mental health outcomes among both adults and children. Similar results are reported for neighbourhood disorder. The relationship between population density and psychological outcomes is mixed, with some evidence reporting worse psychological outcomes for adults living in high density areas, and others reporting no association.

Education about allergen exposure and the provision of allergen reduction equipment is associated with statistically significant reductions in physician diagnosed asthma in children, and number of days ill, but not asthma symptoms, such as wheezing and lung function. While the evidence on dust mite control is not rigorous, it illustrates that the provision of mite impermeable bedding covers is associated with significant reductions in dust mite load but not dust levels in homes. Finally, there is a growing body of evidence to suggest that interventions targeting children's exposure to environmental tobacco smoke, particularly in the home, achieves some degree of success in reducing children's exposure to tobacco smoke.

There was considerable evidence evaluating the impact of built environment interventions on physical activity behaviours. The evidence on travel behaviour change programs is mixed and is not of high methodological quality. While limited evidence exists illustrating a reduction in car use and an increase in walking as opposed to driving, an equal amount of evidence reports no impact on transport behaviour. There is limited evidence that worksite incentives (i.e. subsidy of employees who choose not to drive) have a positive impact on changing travel behaviour.

Interventions targeted at promoting walking and cycling generally (i.e. during leisure time), appear to having beneficial effects on behaviour. For example, brief, face-to-face counselling provided in the workplace, or by clinicians or exercise specialists in primary care was associated with increased self-reported walking at six weeks, and to a lesser extent in the longer term. Interventions delivered via the telephone and/or internet to individuals, and those directed at groups through lay mentored meetings, led walks and group educational sessions, as well as pedometers were also associated with a statistically significant increase in walking in the short term. Successful community-based program to promote walking tended to include a substantial mass media campaign.

Similar findings were observed for cycling. Interventions focused on promoting active communing (i.e. using bikes for transport to anywhere versus a car), along with educational activities and improving the cycle route network in cities, were found to increase the proportion of people cycling, the frequency of cycling per week, and the distance travelled. However, particularly in relation to the proportion of people cycling and distance travelled, the overall effect size remains relatively small. While bike path usage increases with media and social marketing campaigns, and was sustained in the long term, this did not translate into increased population prevalence of cycling.

Improved street lighting or infrastructure projects that increase the ease and safety of street crossing, ensure sidewalk continuity, introduce or enhance traffic calming, such as center islands or raised crosswalks, or enhance the aesthetics of the street area (i.e. landscaping) found positive effects on physical activity behaviour.

This review of the literature represents many systematic reviews and meta-analyses, primary studies and thousands of people. To some extent, the results illustrate that many population health and public health programs are associated with benefits to various populations,particularly related to outcomes such as physical activity and mental health symptoms. However, there remains cause for concern given some of the evidence suggests that various interventions may in fact widen health disparities. Much more research is needed to fully explore if and how interventions impact heath outcomes in different sub populations. However, the evidence presented here provides some direction for moving forward with practice, draws attention to some areas that require ongoing evaluation, and identifies some practices that may not be producing the expected impact and therefore should be examined critically in terms of future investment. While a great deal has been accomplished in population and public health programs there is still much work to be done!