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