MP44-15 ANATOMICAL SCORING SYSTEM FOR ASSESSING PARTIAL NEPHRECTOMY TECHNICAL COMPLEXITY

INTRODUCTION AND OBJECTIVES: We developed a surgical complexity score system based on the arterial vascular anatomy of the kidney in an attempt to overcome the limitations of available nephrometry scoring systems including inconsistent ability to predict clinical outcomes of partial nephrectomy. METHODS: Contrast-enhanced computed tomography images of 179 patients who underwent partial nephrectomy were independently scored by 4 readers. According to the order of vessels involved by the tumor or needed to be transected during partial nephrectomy, assigned score was 1 for interlobular and arcuate arteries; 2 for interlobar arteries; 3S for segmental arteries; and 3H for renal hilum (Fig. 1). The Interobserver variability was assessed with kappa values and percentage of exact matches between each pairwise combination of the 4 readers. Spearman correlation was used to evaluate the association between scores of the most experienced reader (reference score) and ischemia time, estimated blood loss, incidence of urinary fistula within 30 days, and percent change in eGFR from baseline to 6 weeks and 6 months after surgery. RESULTS: All pairwise comparisons of readers’ score assignments were significantly correlated (all p <0.0001) with an average kappa of 0.545 across all reader pairs. The average proportion of exact matches was 69%. Spearman correlations between the complexity score system and surgical outcomes (Table 1) showed significant levels of correlation between the reference category assignments and ischemia time (p <0.0001, coefficient 1⁄4 0.435), estimated blood loss (p 1⁄4 0.008, coefficient 1⁄4 0.198), and urinary fistula formation (p1⁄40.008, coefficient of 0.196). CONCLUSIONS: Similar to other nephrometry scoring systems, our anatomic system is associated with the surgical complexity and perioperative morbidity of partial nephrectomy. However, its intuitiveness and ease of learning is highly favorable compared to existing nephrometry systems. While these initial results are promising, further evaluation of our new scoring system and direct comparisons to the existing nephrometry are required.