Labour market attachment after mild traumatic brain injury: nationwide cohort study with 5-year register follow-up in Denmark.

Objectives: Sickness absence after mild traumatic brain injury (mTBI) is frequent due to postconcussive symptoms. We examined labour market attachment following mTBI up to 5 years postinjury.

Design And Setting: Nationwide cohort study with register follow-up.

Participants: Patients between 18 and 60 years with mTBI (International Classification of Diseases, version 10 diagnosis S06.0) were extracted from the Danish National Patient Register (n=19 732). Controls were matched on sex, age and municipality (n=18 640). Patients with spinal cord and column injuries, traumatic brain injury and concussions 5 years preinjury or as secondary diagnosis to the concussion in the inclusion period were excluded.

Primary And Secondary Outcome Measures: Data were extracted from the Danish Register for Evaluation of Marginalization. Primary outcome was 'not attending ordinary work' defined as receiving any social transfer payment. Secondary outcomes were health-related benefits, limited attachment to the labour market, permanent lack of attachment to the labour market and death.

Results: 5 years after diagnosis, 43% of patients were not attending ordinary work. The odds increased from 6 months (OR 1.30, 95% CI 1.24 to 1.36) to 5 years (OR 1.54, 95% CI 1.45 to 1.63). The odds of health-related benefits were 32% (OR 1.32, 95% CI 1.22 to 1.42) at 6 months and 22% (OR 1.22, 95% CI 1.12 to 1.33) at 5 years. Limited attachment to the labour market showed increased odds at 5 years (OR 1.38, 95% CI 1.27 to 1.51) and the odds of permanent lack of attachment to the labour market were higher for patients compared with controls (OR 2.59, 95% CI 2.30 to 2.92). Death was more than two times higher at 5 years postinjury (OR 2.62, 95% CI 2.10 to 3.26).

Conclusions: 43% of concussed patients were not attending ordinary work 5 years postinjury and received health and social transfer benefits. We conclude that mTBI has a long-term impact on labour market attachment. Prevention and treatment of persisting postconcussive symptoms should be considered.

Trial Registration Number: NCT03214432; Results.