Traumatic Brain Injury Mortality among Colombian Motorcyclists, 2015–2024: Trends and Registry Comparability

Introduction. National surveillance of fatal traumatic brain injury in motorcyclists requires consistent case definitions and attention to changes in administrative reporting. Objective. To characterize national trends, territorial patterns, and demographic profiles of fatal traumatic brain injury among motorcyclists in Colombia from 2015–2024, and to assess comparability between forensic and vital-statistics sources. Method. In this observational study, we analyzed public microdata from the National Institute of Legal Medicine and Forensic Sciences and the National Administrative Department of Statistics, comparing the two sources at the aggregate level without individual-level linkage. In the forensic registry, head injury was defined by the topographic diagnosis “Trauma craneano”. In vital statistics, traumatic brain injury (TBI) was defined by the associated intracranial injury code S06. Analyses included negative binomial trend models, territorial, spatial and demographic analyses, secondary forensic-outcome models, and sensitivity analyses. Results. The forensic registry recorded 40,318 motorcyclist fatalities, of which13,264 involved a recorded head injury (annual proportion, 30.5%–35.7%). Head-injury mortality increased at an average annual incidence rate ratio of 1.035 per year (95% confidence interval 1.009–1.062). The trend remained stable from 2015 to 2021, with a formal statistical test identifying the increase in 2022–2024. Departmental inequalities persisted, although no significant global spatial autocorrelation was detected. Motorcycle exposure was correlated with departmental mortality (Spearman correlation 0.60; 0.59 after adjustment for population size). Vital-statistics counts were 2.9%–24.9% lower than forensic counts before 2022 and 0.1%–1.5% higher thereafter, coinciding with the integration of civil registration systems. Conclusion. Fatal head injury among motorcyclists increased in recent years and exhibited marked territorial disparities. Administrative coverage changes materially affected comparability between sources and should be examined before temporal trends are interpreted.