Geographical Variation in Traumatic Brain Injury Mortality by Proximity to the Nearest Neurosurgeon

Background: Trauma mortality disproportionately affects populations farther from potentially lifesaving trauma care, and traumatic brain injury (TBI) is no exception. Previous examinations have examined proximity to trauma centers as an explanation for trauma mortality, but little is known about the relationship between proximity to neurosurgeons specifically in TBI mortality. Materials and methods: In this cross-sectional study, county-level TBI mortality rates from 2008 to 2014 were examined in relation to the distance to the nearest neurosurgeon and trauma facility. The locations of practicing neurosurgeons and trauma facilities in the United States were determined by geocoding data from the 2017 Medicare Physician and Other Supplier and Provider of Services files (respectively). The association between TBI mortality and the distance from the population-weighted centroid of the county to a closest neurosurgeon and trauma facility was examined using multivariate negative binomial regression. Results: A total of 761 of the 3108 counties (24.5%) in the continental United States were excluded from the analysis because they had 20 or fewer TBI deaths during this time, producing unstable estimates. Excluded counties accounted for 1.67% of the US population. Multivariate analysis revealed a county's mortality increased 10% for every 25 miles from the nearest neurosurgeon (adjusted incident rate ratio: 1.10 [95% confidence interval: 1.08-1.12]; P < 0.001). The distance to the nearest trauma facility was not found to be significantly associated with mortality (adjusted incident rate ratio: 1.01 [95% confidence interval: 0.99-1.03]; P = 0.36). Conclusions: These findings suggest that proximity to neurosurgeons may influence county-level TBI mortality. Further research into this topic with more granular data may help to allocate scarce public health resources.