Global, regional, and national burden of transport-related moderate/severe traumatic brain injury, 1992–2021: a cross-sectional time-trend analysis of GBD 2021

Background: Transport-related moderate/severe traumatic brain injury (m/sTBI) is a major cause of disability and death worldwide, yet its global and country-level trends remain underexplored. Methods: We analyzed Global Burden of Disease (GBD) 2021 estimates of incidence, prevalence, and years lived with disability (YLDs) for transport-related m/sTBI from 1992–2021, stratified by age, sex, and SDI quintile. Age–period–cohort models quantified temporal trends; Bayesian APC forecasting projected burden through 2036. Frontier and inequality analyses assessed performance relative to development and income-related disparities. Results: In 2021, global age-standardized incidence fell by ~ 21% vs. 1992, despite case counts remaining stable (~3.7 million by 2036). High-SDI regions showed the steepest annual declines (>1 %/year), whereas low/low-middle SDI areas saw minimal change. China’s ASIR (age-standardized incidence rates) is projected to decline to ~ 56.5/100 000 by 2036, while India’s will rise to ~ 40.2/100 000. Saudi Arabia sustained the highest ASIR in 2021 (185.7/100 000). Children experienced marked annual decreases, older adults continuous increases. Although absolute inequality (SII) narrowed, relative inequality (CI) worsened, concentrating burden in low-SDI countries. Conclusion: Transport-related m/sTBI remains a persistent global health challenge with widening relative inequities. Successes in China and high-SDI settings demonstrate the impact of robust road-safety policies and trauma systems. Rising trends in India and persistently high rates in Saudi Arabia highlight urgent needs for targeted enforcement, infrastructure improvements, and equitable access to trauma care.