Mild traumatic brain injury (mTBI) accounts for 70-90% of all diagnosed traumatic brain injuries (TBI) affecting approximately 50-300 per 100.000 individuals annually. Persistent post-concussion symptoms are reported in 15-80% of hospital admitted and outpatient treated populations, affecting labour market attachment, academic achievement, income, socio-economic status, social interactions, home management, leisure activities and cohabitation status.

The association between mTBI and long-term trends in cohabitation status, income, academic achievement and socio-economic status has not been thoroughly explored. Previous studies focus on children's academic performance after severe TBI and only few studies include early adulthood and patients with mTBI. Trends in divorce rates are frequently conducted on severe injuries or populations consisting of veterans. Additionally, all studies have failed to apply a national register based design.

Aim The aim of the study is to examine the long-term associations between mTBI and trends in cohabitation status, academic achievement and socio-economic status between pre-injury rates and observed rates at 5 years post-injury. The hypothesis was that by 5 years mTBI would be associated with increased odds of marital breakdown, decreasing academic achievement, decreasing income, decreasing socio-economic status compared to the general population in Denmark.

Methods:

The study is a national register based cohort study with 5 years follow-up of patients with mild traumatic brain injury from 2008 - 2012 in Denmark.

Population:

Patients between 18-60 years diagnosed with concussion (ICD-10 S06.0) were extracted from the Danish National Patient Register between (2003-2007). Patients with major neurological injuries and previous concussions at the index date and 5 years before the index date (1998-2007) were excluded. Patients who were not resident in Denmark 5 years before and during the inclusion period were also excluded (1998-2007).

Data will be retrieved from several national databases, including: the Danish national patient register, Danish Civil Registration System (CRS), the Danish Education Registers, the Income Statistics Register and the Employment Classification Module (AKM).

One control of the general population were matched for each case on sex, age and municipality.

Outcome measures are: Cohabitation status, Education, income and socio-economic status.

Inclusion Criteria:

• Concussion (ICD-10 S06.0) (primary diagnosis)(2003-2007)

Exclusion Criteria:

• Major neurological injuries and previous concussions (1998-2007)
• Not resident in Denmark (1998-2007)

Hospital admitted, emergency or outpatient treated patients between 18-60 years diagnosed with concussion (ICD-10 S06.0) are extracted from the Danish National Patient Registre between (2003-2007).