Renal and extrarenal predictors of nephrectomy from the National Trauma Data Bank

Purpose: The kidney is injured in 1.4% to 3.0% of all trauma cases. The management of renal injuries is controversial, as reflected in regional and institutional variations in treatment preferences. Using a national trauma database we identified independent risk factors for nephrectomy. Materials and Methods: The population was selected from the National Trauma Data Bank, a voluntary data repository containing all trauma admissions to 268 participating trauma centers. Patients with renal injuries were identified by Abbreviated Injury Scale codes. Patient demographic, associated injuries and facility characteristics were recorded. Univariate and Poisson regression analysis with clustering by facility was performed. Results: Renal injury was present in 8,465 patients. Nephrectomy was performed in 4% of all blunt and 21% of all cases of penetrating renal injuries. Only 0.5% of blunt renal injury cases underwent repair compared with 15% of those of penetrating injuries. On multivariate analysis renal injury severity was the strongest predictor of nephrectomy. The relative risk of nephrectomy for grade V renal injuries was 146 (95% CI 74 to 289) and 33 (95% CI 13 to 89) in the blunt and penetrating models, respectively. The need for laparotomy and surgery on other intra-abdominal organs predicted nephrectomy in patients with blunt and penetrating injuries. Hospital trauma designation did not statistically impact nephrectomy rates. Conclusions: The severity of renal injury based on the AAST organ injury scale for Renal Trauma is the strongest risk factor for nephrectomy. The need for surgery on other intra-abdominal injuries increases the risk of nephrectomy to a lesser extent. In cases of blunt trauma severe renal injury usually necessitates nephrectomy.