Racial disparities in mortality after severe traumatic brain injury in childhood: mediators identified by Oaxaca-Blinder decomposition of trauma registry data

BACKGROUND: In the United States social disparities in health outcomes are found wherever they are sought, and they have been documented extensively in trauma care. Because social factors cannot cause a trauma outcome directly, there must exist mediating causal factors related to the nature and severity of the injury, the robustness of the victim, access to care, or processes of care. An understanding these mediators is the point of departure for addressing inequities in outcomes. FINDINGS: Data were extracted from the registry of the Trauma Quality Improvement Program of the American College of Surgeons for 2007 through 2010. Inclusion criteria were age less than 19 years and head Abbreviated Injury Scale score of 4, 5, or 6. An Oaxaca-Blinder decomposition was undertaken to analyze the relative contributions of a large set of covariates to the difference in mortality rates between Black and White children. Covariates were aggregated into the following categories: “Severity,” “Structure and Process,” “Mechanism,” “Demographics,” and “Insurance.” Eligible for analysis were 7273 White children and 2320 Black children. There were 1661 deaths (17.3%) The raw mortality rates were 15.6 and 22.8% for White and Black children, respectively. Factors categorized as “Severity” accounted for 95% of the mortality difference, “Mechanism” accounted for 13%, “Insurance” accounted for 5%, and “Demographics” accounted for 2%. The contribution of “Structure and Process” did not attain statistical significance. CONCLUSIONS: Severity of injury accounts for most of the disparity between Black and White children in traumatic brain injury mortality rates. Mechanism, insurance status, and gender make a small contributions. Because insurance status like other social factors cannot directly affect trauma survival, what mediates its contribution requires further study.