Severe traumatic brain injury and long-term survival: a meta-analysis on life expectancy and mortality trends

Traumatic brain injury (TBI) is associated with sustained excess mortality and reduced life expectancy compared with demographically matched populations. Our aim was to clarify the magnitude of this burden and its modifiers. A random-effects meta-analysis of longitudinal observational studies published through July 2025 was performed. PubMed/Medline, Cochrane Library, Google Scholar, PEDro, and EMBASE were searched for studies reporting standardized mortality ratios or life-expectancy data. The overall pooled standardized mortality ratio was 3.19 (95% CI 2.59–3.92; I² = 67.4%), estimated by restricted maximum likelihood with Hartung–Knapp adjustment. Analyses stratified by data-collection era demonstrated a progressive decline in relative mortality from 3.95 (1974–1987) to 2.18 (2004–2019; p = 0.002). Injury-severity gradients based on Glasgow Coma Scale yielded ratios of 4.51, 2.84, and 1.67 for severe, moderate, and mild injuries, respectively (p < 0.001). Age-specific analyses in contemporary cohorts showed the highest relative risk in middle-aged survivors (SMR 7.18 for ages 35–54) and lower ratios in older groups (SMR 2.41 for ≥ 75 years). Mortality peaked within two years post-injury (SMR 6.34) but remained elevated beyond ten years (SMR 2.87). Meta-regression identified study era, follow-up duration, mean age, proportion of severe cases, and sample size as key modifiers, explaining 84.7% of between-study variance. Weighted mean life-expectancy reduction across eight cohorts was 7.6 years. These findings quantify long-term survival burden after TBI and support the development of comprehensive, lifelong management strategies.