Traumatic brain injury outcomes across human development index strata in 29 countries.

Prior large-scale multicountry studies of traumatic brain injury (TBI) have either focused on surgically managed patients across development settings or characterized the full case-mix in predominantly high-income regions, leaving operative and nonoperative TBI across the human development spectrum incompletely defined. We present the Global Neurosurgical Study-1, integrating operative and nonoperative TBI across all Human Development Index (HDI) tiers. This prospective cohort included 2,165 patients from 100 hospitals in 29 countries between 2019 and 2022. Disparities were noted: median age ranged from 32 years (high-HDI) to 63 years (very-high-HDI); traffic injuries were the predominant cause of TBI in low-HDI (65.8%) versus falls in very-high-HDI (66%); and 69.3% of patients in the low-HDI tier arrived via private vehicles versus 13% for the very-high-HDI tier. Using mixed-effects logistic regression with inverse probability weighting, the adjusted mortality odds were highest in high-HDI tier (odds ratio 3.13, 95% confidence intervals 1.12-8.78) relative to the very-high-HDI, with no statistically significant elevation in low- or medium-HDI tiers. No dose-response relationship was noted between mortality and HDI. Inequities in injury mechanisms, patient demographics and prehospital access were drivers of outcome disparities. These findings suggest that HDI-stratified prevention targeting injury mechanisms and prehospital care may reduce the global TBI burden more effectively than hospital-based measures alone.