Background: Severe traumatic brain injury (TBI) is a leading cause of complex and persistent disability. Yet, long-term change in global functioning and determinants of this change remain unclear.

Objectives: This study aimed to assess change in global functioning in the long term after severe TBI and factors associated with the change.

Methods: This was a prospective observational study of an inception cohort of adults with severe TBI in the Paris area (PariS-TBI). Outcome was assessed at 1, 4, and 8 years post-injury. For the included participants (n=257), change in global outcome between 4 and 8 years was evaluated with the Glasgow Outcome Scale Extended (GOSE) score, and its association with pre-injury, injury-related and post-injury variables was tested with univariate and multivariable analyses.

Results: More than half of the 73 participants evaluated at both 4 and 8 years showed global improvement (of at least one point) in GOSE score and an improvement in mood, executive function, and subjective complaints. On univariate analysis, none of the pre-injury, injury or post-injury variables were associated with GOSE score change between 4 and 8 years, except for GOSE score at 4 years (rho = -0.24, p=0.04). On multivariable analysis, probability of increased GOSE score was associated with more years of education (odds ratio 1.18 [95% confidence interval 1.02-1.37], p=0.03). The change in GOSE score was significantly correlated with change in Hospital Anxiety Depression Scale score between 4 and 8 years (rho = -0.42, p<0.001).

Conclusions: Most participants with severe TBI in the present sample showed a late improvement (4 to 8 years post-injury) in global functioning. Of the socio-demographic and injury-related factors, only more years of education was associated with improvement in global functioning. Decreased anxiety and depression symptoms were associated with improved global functioning. Targeting interventions to enhance resilience may be the most effective in the long term after severe TBI.