Reliability and reproducibility of the American Association for the Surgery of Trauma scaling for renal injury and impact on radiologic follow-up.

INTRODUCTION: The American Association for the Surgery of Trauma (AAST) Organ Injury Scale (OIS) is the most used classification for renal trauma. It determines the radiologic monitoring, only recommended for high-grade injuries. The aim of this study was to assess the subjectivity of AAST scaling and its impact on short-term follow-up.

METHODS: We retrospectively reviewed all patients with blunt renal injuries admitted at a university hospital between 2010 and 2015. Computed Tomography (CT) scan were analyzed and injuries graded according to AAST OIS independently by a senior radiologist, a senior urologist who was blind to clinical data and a resident urologist. Grading disagreements were analyzed collegially to obtain a final rating. The agreement of AAST scaling was evaluated through the Cohen's Kappa coefficient.

RESULTS: Ninety-seven patients had 101 renal injuries: low grade in 58.4% (11.9% grade I, 17.8% grade II, 28.7% grade III) and high grade in 41.6% of cases (23.6% grade IV and 17.8% grade V). The agreement was fair with Kappa coefficient at 0.36. The agreement was moderate in severity sub-division analysis (low or high grade): Kappa coefficient at 0.59. There was a disagreement in 49.5% between the senior urologist's and the senior radiologist's ratings. Those differences brought to a severity group change and radiologic follow-up modification in 34% (n=17).

CONCLUSION: AAST OIS for renal trauma suffers from subjectivity but is improved by severity sub-group analysis. This subjectivity influences the radiologic follow-up but could be reduced by collegiate rating.

LEVEL OF EVIDENCE: 4.