Effect of Gender on Moderate to Severe Traumatic Brain Injury: A Meta-Analysis and Systematic Review

ABSTRACT

PURPOSE: Case-control and cohort studies have reported inconsistent findings for the association between gender and mortality from a traumatic brain injury. We investigated the effect and association of gender on moderate to severe traumatic brain injury using meta-analysis. METHODS: We searched electronic health care databases including MEDLINE (Pubmed), the Cochrane Library, CINAHL, and Koreamed (January 2001 to December 2009) in August 2010. The keywords searched included traumatic brain injury or traumatic head injury, gender, and mortality. Two independent investigators selected and reviewed articles according to predefined inclusion and exclusion criteria. The quality of selected articles was evaluated by applying the Newcastle Ottawa scale. Data were abstracted by predetermined criteria. Odds ratios were calculated and combined using fixed and random effect models. RESULTS: Of 130 articles, four case-control studies and three cohort studies were included in the final analysis. In total, 89,335 patients were included(26,287 females and 63,048 males). Compared with the mortality of male patients, the combined odds ratio for the mortality of female patients was 1.074(95% confidence interval [CI], 1.027~1.124) in a fixed effect model, and 1.319(95% CI, 1.104~1.576) in a random effects model, respectively. The heterogeneity of all participants was severe, so the results were discarded and a subgroup analysis was conducted. The total number of participants was divided into premenopausal and postmenopausal groups by the menopausal age defined in each article. The pooled odds ratio of the premenopausal group was 1.014(95% CI, 0.949~1.083) in the fixed effect model and that of the postmenopausal group was 1.237(95% CI, 0.895~1.712) in the random effects model. The pooled estimate of the random effect model was adopted because of the severe heterogeneity of the postmenopausal group. CONCLUSION: We found no distinct effect of gender on moderate to severe traumatic brain injury. Large-scaled prospective studies based on female hormone levels are needed.