UROGENITAL TRAUMA

American Association for the Surgery of Trauma Organ Injury Scale I: spleen, liver, and kidney, validation based on the National Trauma Data Bank
Tinkoff G, Esposito TJ, Reed J, Kilgo P, Fildes J, Pasquale M, Meredith JW
Department of Surgery, Christiana Care Health System, Newark, DE, USA
J Am Coll Surg. 2008; 207: 646-55

• Background: This study attempts to validate the American Association for the Surgery of Trauma (AAST) Organ Injury Scale (OIS) for spleen, liver, and kidney injuries using the National Trauma Data Bank (NTDB).
• Study Design: All NTDB entries with Abbreviated Injury Scale codes for spleen, liver, and kidney were classified by OIS grade. Injuries were stratified either as an isolated intraabdominal organ injury or in combination with other abdominal injuries. Isolated abdominal solid organ injuries were additionally stratified by presence of severe head injury and survival past 24 hours. The patients in each grading category were analyzed for mortality, operative rate, hospital length of stay, ICU length of stay, and charges incurred.
• Results: There were 54,148 NTDB entries (2.7%) with Abbreviated Injury Scale-coded injuries to the spleen, liver, or kidney. In 35,897, this was an isolated abdominal solid organ injury. For patients in which the solid organ in question was not the sole abdominal injury, a statistically significant increase (p < or = 0.05) in mortality, organ-specific operative rate, and hospital charges was associated with increasing OIS grade; the exception was grade VI hepatic injuries. Hospital and ICU lengths of stay did not show substantial increase with increasing OIS grade. When isolated organ injuries were examined, there were statistically significant increases (p < or = 0.05) in all outcomes variables corresponding with increasing OIS grade. Severe head injury appears to influence mortality, but none of the other outcomes variables. Patients with other intraabdominal injuries had comparable quantitative outcomes results with the isolated abdominal organ injury groups for all OIS grades.
• Conclusions: This study validates and quantifies outcomes reflective of increasing injury severity associated with increasing OIS grades for specific solid organ injuries alone, and in combination with other abdominal injuries.
  
  
• Editorial Comment
  The original AAST classification schema for traumatic renal injuries was published back in 1989 in the Journal of Trauma.(1) The sub-classification of the injuries into grades I - IV were mostly based on expert opinion and poorly constructed retrospective analyses. Despite such poor Oxford Level of Evidence of support for the classification schema, it has stood the test of time. The above paper by Tinkoff et al. is based on Nation Trauma Data Bank (NTDB) V.5.0 and Kuan et al. (2) based on NTBD V.4.0 came to the same conclusions as the reproducible validity of the scaling. The strength of the NTDB is that it is a large repository of trauma data from 405 trauma centers from across the US. Such pooling of data results in large numbers and the power to make statistically significant conclusions. As the standard of care for blunt Grade 1-IV renal injuries is nonoperative and isolated low grade penetrating injuries also trending to nonoperative, it is not surprising that NTDB data shows that 90. 9 % of all renal injuries can be safely managed non-operatively. Furthermore, patients with isolated kidney injuries, where severe traumatic brain injuries and deaths < 24 hours from arrival at the ED were excluded from study showed an incremental and statistically significant increase across all parameters from Grade I and II to Grade V - such as in mortality (1.5% to 10.7%), surgical exploration (4% to 73.3%), length of hospitalization (8.0 to 16.8 days) to ICU days (3.2 to 8.5 days). Another interesting finding was the economics of solid organ injuries. Hospital charges for solid organ injury were remarkably similar for liver, spleen and kidney. Average overall hospital charges are $72, 263 - $75,781. With isolated kidney injuries, the charges were about $6000 per day.

References
1. Moore EE, Shackford SR, Pachter HL, McAninch JW, Browner BD, Champion HR, et al.: Organ injury scaling: spleen, liver, and kidney. J Trauma. 1989; 29: 1664-6.
2. Kuan JK, Wright JL, Nathens AB, Rivara FP, Wessells H; American Association for the Surgery of Trauma: American Association for the Surgery of Trauma Organ Injury Scale for kidney injuries predicts nephrectomy, dialysis, and death in patients with blunt injury and nephrectomy for penetrating injuries. J Trauma. 2006; 60: 351-6.

Dr. Steven B. Brandes
Associate Professor, Division of Urologic Surgery
Washington University in St. Louis
St. Louis, Missouri, USA
E-mail: brandess@wudosis.wustl.edu