Design of a Location-Based Case-Control Study of Built Environment Risk Factors for Pedestrian Fatalities in the U.S

Area of Science:

• Environmental Epidemiology
• Transportation Safety Research
• Geographic Information Systems (GIS) in Public Health

Background:

• Pedestrian fatalities are a significant public health concern, often linked to environmental factors.
• Traditional epidemiological designs may not be optimal for studying location-specific environmental exposures.
• A novel approach is needed to systematically investigate the environmental characteristics of locations where pedestrian fatalities occur.

Purpose of the Study:

• To introduce and apply a location-based case-control design for studying pedestrian fatalities.
• To identify environmental characteristics associated with pedestrian fatality risk at specific locations.
• To utilize a large-scale cohort of U.S. transportation infrastructure for analysis.

Main Methods:

• A location-based case-control study nested within a large cohort of U.S. transportation locations (intersections, road segments, ramps).
• Inclusion of 9,612,698 intersections, 17,737,728 road segments, and 222,318 ramp segments across 384 Metropolitan Statistical Areas.
• Follow-up from 2017-2018 using the Fatality Analysis Reporting System (FARS) to identify 10,587 pedestrian fatalities (case-locations) and 21,174 matched control locations via incidence density sampling.
• Utilizing Geographic Information Systems (GIS), spatially linked administrative data, and Google Street View for virtual audits to characterize locations.

Main Results:

• Successfully identified 10,587 pedestrian fatalities within the defined cohort of transportation locations.
• Selected 21,174 matched control locations using incidence density sampling for comparison.
• Characterization of case and control locations using GIS and virtual audits is currently in progress.

Conclusions:

• The location-based case-control design is a feasible and robust methodology for investigating environmental risk factors in pedestrian fatalities.
• This approach allows for a detailed examination of the built environment's role in traffic safety.
• Future analyses will provide critical insights into environmental determinants of pedestrian safety.