Explaining outcome differences between men and women following mild traumatic brain injury.

Men and women differ in outcomes following mild traumatic brain injury (TBI). In the CENTER-TBI study, we previously found that women had worse 6-month functional outcome (Glasgow Outcome Score Extended (GOSE)), health-related quality of life (HRQoL), and mental health following mild TBI. The aim of this study was to investigate whether those differences were mediated by psychiatric history, gender- related sociodemographic variables, or by care pathways. We analyzed sex/gender differences in 6-month GOSE, generic and TBI-specific HRQoL, post-concussion and mental health symptoms using three sets of mediators: psychiatric history, sociodemographic variables (living alone, living with children, education and employment status/job category), and care-pathways (referral to study hospital and discharge destination after Emergency Room); while controlling for a substantial number of potential confounders (pre-injury health, and injury-related characteristics). We included 1842 men and 1022 women (16+) with a Glasgow Coma Score 13-15, amongst whom 83% had GOSE available and about 60% other 6-month outcomes. We used natural effects models to decompose the total effect of sex/gender on the outcomes into indirect effects that passed through the specified mediators, and the remaining direct effects. In our study population, women had worse outcomes and these were only partly explained by psychiatric history, and not considerably explained by sociodemographic variables nor by care pathways. Other factors than differences in specified variables seem to underlie observed differences between men and women in outcomes after mild TBI. Future studies should explore more aspects of gender roles and identity, and biological factors underpinning sex and gender differences in TBI outcomes.