Background: This study updates the American Association for the Surgery of Trauma (AAST) Organ Injury Scale (OIS) for renal trauma using evidence-based criteria for bleeding control intervention.
Methods: This was a secondary analysis of a multicenter retrospective study including patients with high-grade renal trauma from seven level 1 trauma centers from 2013 to 2018. All eligible patients were assigned new renal trauma grades based on revised criteria. The primary outcome used to measure injury severity was intervention for renal bleeding. Secondary outcomes included intervention for urinary extravasation, units of packed red blood cells transfused within 24 hours, and mortality. To test the revised grading system, we performed mixed-effect logistic regression adjusted for multiple baseline demographic and trauma covariates. We determined the area under the curve (AUC) to assess accuracy of predicting bleeding interventions from the revised grading system and compared this to 2018 AAST OIS.
Results: Based on the 2018 OIS grading system, we included 549 patients with AAST grades III to V injuries and computed tomography scans (III, 52% [n = 284]; IV, 45% [n = 249]; and V, 3% [n = 16]). Among these patients, 89% experienced blunt injury (n = 491), and 12% (n = 64) underwent intervention for bleeding. After applying the revised grading criteria, 60% (n = 329) of patients were downgraded, and 4% (n = 23) were upgraded; 2.8% (n = 7) downgraded from grade V to IV, and 69.5% (n = 173) downgraded from grade IV to III. The revised renal trauma grading system demonstrated improved predictive ability for bleeding interventions (2018 AUC, 0.805; revised AUC, 0.883; p = 0.001) and number of units of packed red blood cells transfused. When we removed urinary injury from the revised system, there was no difference in its predictive ability for renal hemorrhage intervention.
Conclusion: A revised renal trauma grading system better delineates the need for hemostatic interventions than the current AAST OIS renal trauma grading system.
Level of evidence: Diagnostic Test/Criteria; Level III.
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