Evaluating the quality of evidence on built environment interventions within road safety public policies across five urban traffic environments in Canada
Author(s): Richmond, Siladi, Friman, Fuselli, Pike, Macpherson
Slidedeck Presentation Only:
Abstract:
Background/Context: Injuries caused by motor vehicle collisions are a significant public health problem. Addressing road safety from a public health perspective requires the use of a population health approach. A critical stage of this approach includes making decisions to implement interventions that are based in evidence. Given the breadth of literature in the area of road safety, in addition to the variability in effectiveness of the interventions themselves, there is a need for a synthesis of road safety interventions implemented at a policy level, as well as critical appraisal of the evidence within each policy. This information can be used by public health and transport practitioners to assist in policy-making decisions that require evidence of intervention effectiveness from the peer-reviewed literature as one part of the evidence-informed decision making process.
Aims/Objectives: The objective of this study was to critically appraise and determine the level of evidence of common interventions embedded in road safety policies implemented at a population level.
Methods/Targets: A two-phase critical appraisal process was completed for this project. First, a review of all interventions by study design was completed and each study was graded using a modified version of the Centre for Evidence-Based Medicine grading system. For the second phase, an evidence synthesis framework was used to critically appraise and determine the level of evidence of each intervention. Data that was previously collected through an environmental scan of road safety policies implemented in urban traffic environments (5 large municipalities across Canada) was used to determine the interventions to be evaluated. Interventions embedded within each road safety policy were extracted from the data collection. Two independent reviewers searched for peer-reviewed literature that evaluated the effectiveness of the intervention at a population level. For the first phase, each study was graded as high, medium or low quality. For the second phase, each study found was critically appraised using a critical appraisal tool, specific to each study design and the level of evidence was determined using guidance from the Canadian Guide to Clinical Preventive Health Care and the Community Guide.
Results/Activities: Interventions found in the policy documents across all municipalities were grouped into five major intervention types: traffic calming, bicycle-related, sidewalks and streets, interventions and crossings, and school-related interventions. The critical appraisal of the evidence demonstrated considerable variability in the quality and level of effectiveness across interventions. For traffic calming, streets and sidewalks, intersections and crossings, the quality of evidence ranged from medium to high based on study design. For bicycle and school-related interventions, the quality of evidence ranged from low to high. The quality evidence varied significantly particularly when stratified by road user, or when considered in the context of multi-factorial interventions.
Discussion/Deliverables: There is a breadth of road safety policies implemented at a municipal level; however, the quality of evidence associated with these interventions varies based on both study design and internal and external validity. There is variability of effectiveness at the road user level, as well as within the context of multi-factorial interventions. To successfully address road safety from a public health perspective, sectors charged with their implementation should work together to ensure that interventions are evidence-based and that this information is used in decision making.
Conclusions: This study demonstrates a high degree of variability exists in the quality of evidence and intervention effectiveness within road safety policies implemented in five urban traffic environments across Canada.