Five-Year Follow-Up of Work Disability After Traumatic Brain Injury: A Nationwide Swedish Matched Cohort Study of...

Traumatic brain injury (TBI) is a leading cause of long-term disability in working-age populations. Return to work is a key marker of recovery, yet most studies assess it as binary at fixed time points. We aimed to estimate transition probabilities to and from work disability during 5 years after TBI and how injury severity and preinjury sociodemographic and medical factors influence these probabilities.

We conducted a nationwide matched cohort study in Sweden using linked registers. Individuals aged 21-60 years with a TBI diagnosis between 2005 and 2016 were compared with up to 10 matched non-TBI individuals. TBI severity was proxied by care characteristics: TBI A (emergency visit or ≤2 days), TBI B (≥3 days), and TBI C (neurosurgery). Transition probabilities to and from work disability (>14 days sickness absence) were estimated with multistate models. Sociodemographic and medical factors were assessed with Cox regression.

The cohort included 98,256 individuals with TBI and 981,191 matched non-TBI individuals (median age 39 years; 43% women). Transition probabilities to work disability were higher in all TBI groups: at 30 days, 5.5% (95% CI 5.4-5.7) for TBI A, 29% (28.0-30.7) for TBI B, and 43% (38.2-47.3) for TBI C, vs 0.5% (0.5-0.6) in non-TBI; at 5 years, 7.1% (7.0-7.3), 10.9% (10.2-11.7), and 12.9% (10.7-15.7), vs 4.0% (4.0-4.1). In TBI A and B, higher probability was predicted by older age (TBI A hazard ratio 1.23, 95% CI 1.20-1.26; TBI B 1.34, 1.21-1.48), female sex (TBI A 1.59, 1.56-1.62; TBI B 1.35, 1.26-1.44), and psychiatric disorders (TBI A 1.34, 1.30-1.39; TBI B 1.28, 1.11-1.48), while higher education (TBI A 0.83, 0.81-0.86) and city residence (TBI A 0.92, 0.90-0.95; TBI B 0.88, 0.80-0.95) were protective. In TBI C, only older age remained significant (1.59, 1.17-2.14).

TBI was associated with persistently elevated transition probabilities to work disability across all severity groups, with early peaks in TBI B and C and a delayed increase in TBI A, influenced by sociodemographic and medical factors. However, the lack of standardized severity grading limits comparison with other studies. Still, these results suggest TBI increases long-term risk of work disability, supporting sustained individualized rehabilitation.