BackgroundWhole-body computed tomography (WBCT) is increasingly being incorporated into the initial management of blunt trauma patients. Several observational studies have suggested that, compared to selective CT, WBCT is associated with lower mortality. In contrast, a randomized controlled trial found no significant difference in survival between patients undergoing WBCT compared to selective CT. Our objective was to confirm the association between WBCT and in-hospital mortality among adult severe blunt trauma patients. MethodsThis was a retrospective cohort study based on Japan Trauma Data Bank 2004-2015 registry data. The study population comprised adult severe blunt trauma patients with at least one abnormal vital sign: systolic blood pressure 100mmHg, heart rate 120, respiratory rate 30 or 10, or Glasgow Coma Score 13. The primary outcome was in-hospital mortality. To adjust for both measured and unmeasured confounders, we performed instrumental variable (IV) analysis to compare the in-hospital mortality of patients undergoing WBCT with those undergoing selective CT.ResultsOf 40,435 patients who were eligible for this study, 19,766 (48.9%) patients underwent WBCT. The proportion of patients undergoing WBCT significantly increased during the study period, from 10.7% in 2004 to 59.6% in 2015. Primary IV analysis showed a significant association between WBCT and lower in-hospital mortality (odds ratio 0.84, 95% confidence interval 0.72-0.98).ConclusionsWBCT can be beneficial in patients with blunt trauma which has compromised vital signs. These findings from a nationwide study suggest that physicians should consider WBCT for blunt trauma patients when warranted by vital signs.