Trends in collisions and traffic mortality rates in Mexico City: A comparison of six data sources.

<h4>Introduction</h4>Improving data quality is an international recommendation to advance road safety. Mexico City has several sources of road safety data which are used interchangeably, no study has analyzed their strengths and limitations.<h4>Objective</h4>We aimed to compare the trends of four indicators (total collision rate, collision resulting in injury rate, fatality rate and mortality rate) across six open access datasets of Mexico City, between 2015-2022, and to discuss their differences, strengths and limitations.<h4>Materials and methods</h4>Datasets consulted were from: police records, emergency calls, an insurance company, the justice department, the Institute for Forensic Science and vital registrations for the period 2015-2022. We descriptively compared rates and their trends and estimated percentage changes from the start to the end of the period.<h4>Results</h4>The collision, collision resulting in injury and mortality rates varied greatly across datasets. Trends over time were consistent in direction; they showed a decline in collisions and deaths from 2015 to 2020 and an increase from 2020 to 2022. However, the magnitude of the change was very different across datasets.<h4>Conclusions</h4>None of the datasets was comprehensive enough to provide a full picture of road safety in Mexico City. Differences between datasets may be related to the methodology used to report and register collisions and to the reach and remit of each institution. Our results highlight the need for a more comprehensive data information system for road safety in Mexico City and across the country. We call on researchers, practitioners and policy makers to use available data sources responsibly and to be transparent about their limitations until we progress to a unique source of information.