Is Sex an Indicator of Prognosis After Mild Traumatic Brain Injury: A Systematic Analysis of the Findings of the World Health Organization Collaborating Centre Task Force on Mild Traumatic Brain Injury and the International Collaboration on Mild Traumatic Brain Injury Prognosis

Abstract Objective To determine sex differences in the recovery and prognosis after mild traumatic brain injury (MTBI) in adults and children. Data Sources We analyzed all scientifically admissible primary studies in the World Health Organization (WHO) (n=120) and International Collaboration on Mild Traumatic Brain Injury Prognosis (ICoMP) (n=101) systematic reviews regarding prognosis of MTBI for sex-stratified findings. They searched MEDLINE and other databases from 1980 through 2000 (WHO) and 2001 through 2012 (ICoMP) for published, peer-reviewed reports in English and other languages. Study Selection We selected controlled trials and cohort and case-control studies that assessed the effect of sex on outcomes after MTBI. Data Extraction Data from the eligible studies from both systematic reviews combined (n=14, 7%) were extracted into evidence tables. Data Synthesis Prognostic information relating to sex was prioritized according to design as exploratory or confirmatory, and a best-evidence synthesis was conducted. After MTBI, females may have a higher risk of epilepsy (children, young adults) and suicide, and use more health care services; males may be at higher risk for schizophrenia. Most studies did not find a sex difference for postconcussion symptoms in children and adults. No sex difference was found for risk of dementia and primary brain tumor, return to work, or posttraumatic stress syndrome. Conclusions Sex is not a well-studied prognostic indicator for recovery after MTBI, but small sex differences were found for some outcomes. More well-designed studies are needed that report outcomes according to sex and control for potential confounders.